Energy audit

VIVEK VISWANADH
M.Tech(Ph.D)
Assistant Professor
Department of Electrical and Electronics Engineering
Vignan’s Institute of Information Technology(A)

UNIT-1:
BASIC PRINCIPLES OF ENERGY MANAGEMENT
Energy Audit-Definition:
Energy Audit is the key to a systematic approach for decision-making in the area of
energy management. It attempts to balance the total energy inputs with its use, and serves to
identify all the energy streams in a facility. It quantifies energy usage according to its discrete
functions. Industrial energy audit is an effective tool in defining and pursuing comprehensive
energy management programme.
As per the Energy Conservation Act, 2001, Energy Audit is defined as "the
verification, monitoring and analysis of use of energy including submission of technical
report containing recommendations for improving energy efficiency with cost benefit
analysis and an action plan to reduce energy consumption".
Need for Energy Audit
In any industry, the three top operating expenses are often found to be energy (both
electrical and thermal), labour and materials. If one were to relate to the manageability of the
cost or potential cost savings in each of the above components, energy would invariably
emerge as a top ranker, and thus energy management function constitutes a strategic area for
cost reduction.
Energy Audit will help to understand more about the ways energy and fuel are used in
any industry, and help in identifying the areas where waste can occur and where scope for
improvement exists.
The Energy Audit would give a positive orientation to the energy cost reduction,
preventive maintenance and quality control programmes which are vital for production and
utility activities. Such an audit programme will help to keep focus on variations which occur
in the energy costs, availability and reliability of supply of energy, decide on appropriate
energy mix, identify energy conservation technologies, retrofit for energy conservation
equipment etc.
In general, Energy Audit is the translation of conservation ideas into realities, by
lending technically feasible solutions with economic and other organizational considerations
within a specified time frame.
The primary objective of Energy Audit is to determine ways to reduce energy
consumption per unit of product output or to lower operating costs. Energy Audit provides a
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"bench-mark" (Reference point) for managing energy in the organization and also provides
the basis for planning a more effective use of energy throughout the organization.
Objectives of Energy Audit:
The energy audit provides the vital information base for overall energy conservation
programme covering essentially energy utilization analysis and evaluation of energy
conservation measures.
It aims at:
i. Assessing present pattern of energy consumption in different cost centres of
operations.
ii. Relating energy inputs and production output
iii. Identifying potential areas of thermal and electrical energy economy.
iv. Highlighting wastage in major areas
v. Fixing of energy saving potential targets for individual cost centres
vi. Implementation of measures of energy conservation and realisation ofsavings.
The overall objectives of the Energy Audit are accomplished by:
i. Identifying areas of improvement and formulation of energy conservation measures
requiring no investment or marginal investment through system improvements and
optimisation of operations.
ii. Identifying areas requiring major investment by incorporation of modern energy
efficient equipment and up-gradation of existing equipment
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Type of Energy Audit:
The type of Energy Audit to be performed depends on:
 Function and type of industry,
 Depth to which final audit is needed and
 Potential and magnitude of cost reduction desired.
Thus Energy Audit can be classified into the following two types.
i) Preliminary Energy Audit
ii) Detailed Energy Audit

4
Preliminary Energy Audit:
The preliminary audit or simple audit or walk through audit is the simplest and quickest type
of audit. It involves minimal interviews with site operating personnel, a brief review of
facility utility bills and other operating data, and a walk through of the facility to become
familiar with the building operation and to identify any glaring areas of energy waste or
inefficiency. Preliminary analysis made to asses building energy efficiency to identify not
only simple and low cost improvements but also a list of energy conservation measures to
orient the future detailed audit. This inspection is based on visual verifications, study of
installed equipment and operating data and detailed analysis of recorded energy consumption
collected during the benchmarking phase. Following activities are envisaged in the
preliminary energy audit.
• Establish energy consumption in the organization
• Estimate the scope for saving
• Identify the most likely (and the easiest areas for attention
• Identify immediate (especially no-/low-cost) improvements/ savings
• Set a 'reference point'
• Identify areas for more detailed study/measurement.
Preliminary energy audit uses existing, or easily obtained data. The plant data analysis is
useful in managing and analyzing the complex plant data to optimize process performance.
Typically, only major problem areas will be covered during this type of audit. Corrective
measures are briefly described, and quick estimates of implementation cost, potential
operating cost savings, and simple pay back periods are provided. This level of detail, while
not sufficient for reaching a final decision on implementing proposed measure, it is adequate
to prioritize energy efficient projects and to determine the need for a more detailed audit.
Detailed Energy Audit:
A comprehensive audit provides a detailed energy project implementation plan for a
facility, since it evaluates all major energy using systems. This type of audit offers the most
accurate estimate of energy savings and cost. It considers the interactive effects of all
projects, accounts for the energy use of all major equipment, and includes detailed energy
cost saving calculations and project cost. In a comprehensive audit, one of the key elements is
the energy balance. This is based on an inventory of energy using systems, assumptions of
current operating conditions and calculations of energy use. This estimated use is then

compared to utility bill charges. Detailed energy auditing is carried out in three phases: Phase
I, II and III.
Phase I - Pre Audit Phase
Phase II - Audit Phase
Phase III - Post Audit Phase
A Guide
methodology
methodology
for Conducting Energy Audit at a Glance Industry-to-industry, the of Energy
Audits needs to be flexible. A comprehensive ten-step for conduct of Energy
Audit at field level is presented below. Energy
Manager and Energy Auditor may follow these steps to start with and add/change as per their
needs and industry types
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Step
No. PLAN OF ACTION PURPOSE / RESULTS
Phase I –Pre Audit Phase
Step
1
· Plan and organise ·Resource planning, Establish/organize a Energy
audit team
· Walk through Audit · Organize Instruments & time frame
· Informal Interview with Energy
Manager, Production / Plant
Manager
· Macro Data collection (suitable to type of
industry.)
· Familiarization of process/plant activities
·First hand observation & Assessment of current level
operation and practices
Step
2
Conduct of brief meeting /
awareness programme with all
divisional heads and persons
concerned (2-3 hrs.)
· Building up cooperation
· Issue questionnaire for each department
· Orientation, awareness creation
Phase II –Audit Phase
Step
3
Primary data gathering, Process
Flow Diagram, & Energy Utility
Diagram
· Historic data analysis, Baseline data collection
· Prepare process flow charts
· All service utilities system diagram (Example: Single
line power distribution diagram, water, compressed air
& steam distribution.
· Design, operating data and schedule of operation
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·Annual Energy Bill and energy consumption pattern
(Refer manual, log sheet, name plate, interview)
Step
4
Conduct survey and monitoring Motor survey, Insulation, and Lighting survey with
portable instruments for collection of more and
accurate data. Confirm and compare operating data
with design data.
Step
5
Conduct of detailed trials
/experiments for selected energy
guzzlers
Trials/Experiments:
. 24 hours power monitoring (MD, PF, kWh etc.)
. Load variations trends in pumps, fan compressors
etc.
. Boiler/Efficiency trials for (4 – 8 hours)
. Furnace Efficiency trials
. Equipments Performance experiments etc
Step
6 Analysis of energy use
· Energy and Material balance & energy loss/waste
analysis
Step
7
Identification and development of
Energy Conservation(ENCON)
opportunities
· Identification & Consolidation ENCON measures
. Conceive, develop, and refine ideas
. Review the previous ideas suggested by unit
personal
. Review the previous ideas suggested by energy audit
if any
. Use brainstorming and value analysis techniques
. Contact vendors for new/efficient technology
Step
8
Cost benefit analysis ·Assess technical feasibility, economic viability and
prioritization of ENCON options for implementation
· Select the most promising projects
· Prioritise by low, medium, long term measures
Step
9
Reporting & Presentation to the
Top Management
Documentation, Report Presentation to the top
Management.
Phase III –Post Audit phase
Step
10
Implementation and Follow-up Assist and Implement ENCON recommendation
measures and Monitor the performance
. Action plan, Schedule for implementation
. Follow-up and periodic review
𝐸𝑛𝑒𝑟𝑔𝑦 𝐼𝑛𝑑𝑒𝑥=
ENERGY INDEX:
It is a useful parameter to monitor and compare energy consumption whenever the
industry/firm (or a facility in general) is producing a specified product.
Energyused
Productionoutput
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This may be calculated weekly/monthly/annually. For better monitoring, the total energy indices are
calculated. If there is any increase or decrease in the Energy Index, with the implementation of any
conservation scheme, the particular source can be identified and investigatedimmediately.
COST INDEX:
Another parameter which is useful in monitoring and assessing energy use of a facility is cost index. It
is defined as the ratio of the cost of energy to the production output. Any changes in energy
consumption which can be investigated and remedied are indicated by comparison of cost indices. The
trends and fluctuations are clearly visible with such comparisons.
PIE CHART:
This is a circular chart depicting the energy usage where the quantity of aparticular type is
represented as a segment of a circle. The size of the segment is proportional to the energy consumption
using a particular fuel relative to the fuel usage. The relevant conversion factors are used to rationalize
all the energy units to one particular unit.
Sankey Diagrams:
All the energy flows in and out of a Facility arc represented by Sankey diagram, The
widths of the bands are directly proportional to energy production, utilization and losses. The
primary energy resources which in this case arc the gas, electricity and oil, represent the
energy inputs at the left-hand side of the sankey diagram. A typical Sankey diagram is shown
representing energy usage, MJ/hour.

For a small factory, the energy input and losses are shown in the Sankey diagram above. The
units used are kWh. The losses are identified and quantified and the required-action is also
suggested in the diagram.
Sankey diagrams are very difficult to construct since they involve accurate measurements for all
energy flows i.e., inputs, throughputs, and outputs. Considerable metering and instrumentation are
needed in this regard. This construction or drawing of Sankey diagram is an excellent exercise in
energy management.
LOAD PROFILE:
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It is a tedious task to draw Pie charts and Sankey diagrams to monitor and check energy usage
on weekly or monthly basis. Load profile is an alternative method that is used for monitoring energy
consumption on a time dependent basis. The usage of oil, coal, gas and electricity, considering all the
months are shown as cumulative monthly load profile. The results illustrate seasonal variations. After a
period of time, energy consumption patterns emerge and it is possible to indicate at a glance whether
an area is exceeding its predicted energy use.
Energy conservation schemes:
One of the primary sources of energy in future is the conservation of energy. Energy
conservation should always be viewed in a broad perspective in which financial manpower and
environmental factors all play a role. The investment for energy conservation, in general, is to be
regarded and judged exactly in the same manner as any other form of capital investment. On economic
basis, energy conservation may be classified into three categories as under:
(a) Short-term energy conservation schemes
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(b) Medium-term energy conservation schemes
(c) Long-term energy conservation schemes
Short-and medium-term schemes can achieve savings of 5 to 10%, the long-term schemes may
achieve a further savings of 10 to 15%.
(a)Short-term energy conservation schemes:
This group consists of tasks of tightening of operational control and improved housekeeping.
(i) Furnace efficiencies:
For good combustion, minimum excess air over stoichiometric air is to be maintained. A
continuous monitoring of oxygen level in flue gases is to be done. The oil burners should be
cleaned regularly and well maintained.
(ii) Heal exchangers:
In case of heat exchangers where there is a transfer of useful heat from product streams to feed
streams. The optimum cycles can be determined by continuous performance monitoring. An
improved heat recovery can be achieved by frequent cleaning.
(iii) Good housekeeping:
When natural light is available and sufficient, artificial light should be avoided. During the heating
season doors and windows should be closed as much as possible. Encouragement should be given
to staff to wear suitable clothing in the workingareas.
(iv) Electrical Power:
In most of the industries, electrical power is 'imported'. About 10 to 15% of electrical energy
costs can be reduced by adopting conservation measures. At locations whcrc natural air cooling is
sufficient, the usage of I.D. fans can be avoided. Gravity flow application can minimize pumping
costs of liquids.
(v)Steam usage—The majority of steam leaks should be repaired as soon as possible after they
occur. The quality as well as quantity of steam required should be optimized and a careful control
of the supply and distribution of steam is essential. The payback period for this type of schemes is
less than or equal to one year.
(b) Medium-term energy conservation schemes:
Considering a payback period of less than two years, considerable savings in energy
consumption are often available for quite modest outlays of capital. Some examples are given
below:
(i) Insulation: Improving insulation prevents the leakage of cold air into the room and also
thermal losses in the steam distribution system. Optimum thickness of insulation or critical
radius of insulation is to be evaluated based on the study under consideration. Due
consideration is to be given to economical thickness of insulation also.

(ii)
(iii)
(iv)
The temperature control and operational time of cooling/heating systems.
Whenever necessary, the air compressors are to be replaced.
The reliable measurement and control of energy parameters can be achieved by providing
adequate instrumentation at all places.
Certain processes of the industry need modification. For example, the uncontaminated
steam condensate may be used as boiler feed water. This results in heat recovery in the
condensate as well as in reduction of raw water amount and its treatment costs.
Considerable savings can be obtained by suitably adjusting the electrical power factor
correction.
The control and atomizing of steam in boilers and oil in furnaces is found to be in excess
of the optimum designed value. This optimal value when used results in energy
conservation.
(v)
(vi)
(vii)
(c) Long-term energy conservation schemes:
Further energy saving can be attained by adopting policies which require large amount
of capital expenditure. The return on capital for the long-term investment may not be as good
as that of the medium-term. Economical appraisal techniques are to be used to ensure the
economical viability of such schemes, involving certain modifications to the existing systems
or refurbishments. Some examples are:
(i) Heater modification: The installation of heating tubes, air pre-heaters or any other
suitable heat exchangers results in extraction of more heat from furnace flue gases.
Additional lagging (improved insulation) for storage tanks minimizes thermal energy
losses.
To obtain improved heat recovery, additional heat exchangers are to be provided in
the processing areas.
(ii)
(iii)
Example:
A company uses on an hourly basis, 4.32 x 10^9 J of oil, 11.72 x 10^3 therms of gas and 500 kW of
electricity. Draw a Pie chart for this company's energy usage. (To convert 1 therm to J/s divide by
29.31 x 10^-3)
Sol: All the units are first converted into a particular unit, namely kW, thus
4.32𝑋 109
𝑂𝑖𝑙= =1200𝑘𝑊
3600𝑋 103
11.72𝑋 103
𝐺𝑎𝑠 = =400𝑘𝑊
29.31𝑋 10−3
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Electricty = 500kW
Total hourly energy consumption = 2100kWThen the segment angles of the pie chart are obtained and
percentage of consumption are calculated as:
2100
1200
𝑂𝑖𝑙= 𝑋 3600=2060;57.2%
2100
400
𝐺𝑎𝑠 = 𝑋 3600=680;18.9%
2100
500
𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑖𝑡𝑦= 𝑋 3600=860;23.9%
Pie chart is shown as
The Pie charts may also be extended to indicate the consumption of a particular type of energy
throughout an (Industry) facility. For example, consider the consumption of electricity of an industry.
The consumption, angles and percentages are evaluated as follows:
Office air-conditioning = 150 kW = 100° = 27.8 %
Lighting = 120 kW = 80° = 22.2 %
Boiler house = 90 kW = 60° = 16.7 %
Process = 180 kW = 120° = 33.3 %
Total = 540 kW =360° =100%
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The Pie charts enable the energy manager/energy auditor to identify the areas where energy
conservation opportunities are to be identified, analyzed and evaluated in the order of priority. The
technical feasibility and economical viability of such proposals are then considered for execution or
implementation of them.
Example:
Find the cost index of an industry producing 15000 MT per year. Whose energy cost details are given
as under:
Energy Type Consumption Energy costs/unit in Rupees Total cost in Rupees
Coal 1500 MT 410/MT 615 x 10^3
Oil 18.000 litres 40.0/litre 720 x 10^3
Electricity 1.0 x 10^5kWh 3.0/kWh 300 x 10^3
Total 1635 x 10^3
15x10^
3
Coal cost index = 615 x 10^3
=Rs41.0/MT
Oil cost index =
15x10^
3
720 x 10^3
=Rs48.0/MT
Electricity cost index =
15x10^
3
300 x10^3
=Rs20/MT
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Total cost index =Rs109 /MT
Example:
An industry uses three forms of energy, namely gas, oil and electricity. Their annual energy
consumption is 146 MWh_ 520 MWh and 995 MWh respectively and produces 105 tonnes (MT) per
annum. Calculate the energy indices.
Gasenergyindex =
520x106
105
=5.2kWh/tonne
Oilenergyindex=
146x106
105
=1.46kWh/tonne
Gasenergyindex =
995x106
105
=9.95kWh/tonne
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Total Energy Index = 5.2 + 1.46 + 9.95 = 16.61 kWh/tonne
Principles of energy management:
1. To control the costs of the energy function or service provided, but not the energy.
2. To control energy functions as a product cost, not as a part of manufacturing or
general overhead.
3. To control and meter only the main energy functions
4. To put the major effort of an energy management program in to installing controls
and achieving results
The first principle is to control the costs of the energy function or service provided,
but not the energy. As most operating people have noticed, energy is just a means of
providing some service or benefit. With the possible exception of feed stocks for
petrochemical production, energy is not consumed directly. It is always converted into some
useful function. In most organizations it will pay to be even more specific about the function
provided. For instance, evaporation, distillation, drying, and reheat are all typical of the uses
to which process heat is put. In some cases it has also been useful to break down the heat in
terms of temperature so that the opportunities for matching the heat source to the work
requirement can be utilized.
In addition to energy costs, it is useful to measure the depreciation, maintenance,
labour, and other operating costs involved in providing the conversion equipment necessary

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to deliver required services. These costs add as much as 50% to the fuel cost. It is the total
cost of these functions that must be managed and controlled, not the Btu of energy.
Second principle of energy management is to control energy functions as a product
cost, not as a part of manufacturing or general overhead. It is surprising how many
companies still lump all energy costs into one general or manufacturing overhead account
without identifying those products with the highest energy function cost. In most cases,
energy functions must become part of the standard cost system so that each function can be
assessed as to its specific impact on the product cost. The minimum theoretical energy
expenditure to produce a given product can usually be determined en route to establishing a
standard energy cost for that product. As in all production cost functions, the minimum
standard is often difficult to meet, but it can serve as an indicator of the size of the
opportunity. In comparing actual values with minimum values, four possible approaches can
be taken to reduce the variance, usually in this order:
1. An hourly or daily control system can be installed to keep the function cost at the
desired level.
2. Fuel requirements can be switched to a cheaper and more available form.
3. A change can be made to the process methodology to reduce the need for the function.
4. New equipment can be installed to reduce the cost of the function.
The starting point for reducing costs should be in achieving the minimum cost
possible with the present equipment and processes. Installing management control systems
can indicate what the lowest possible energy use is in a well-controlled situation. It is only at
that point when a change in process or equipment configuration should be considered. An
equipment change prior to actually minimizing the expenditure under the present system may
lead to over sizing new equipment or replacing equipment for unnecessary functions
The third principle is to control and meter only the main energy functions—the
roughly 20% that make up 80% of the costs. A few functions usually account for a majority
of the costs. It is important to focus controls on those that represent the meaningful costs and
aggregate the remaining items in a general category. Many manufacturing plants have only
one meter, that leading from the gas main or electric main into the plant from the outside
source. Regardless of the reasonableness of the standard cost established, the inability to
measure actual consumption against that standard will render such a system useless. Sub-
metering the main functions can provide the information not only to measure but to control

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costs in a short time interval. The cost of metering and sub-metering is usually incidental to
the potential for realizing significant cost improvements in the main energy functions of a
production system.
The fourth principle is to put the major effort of an energy management program in
to installing controls and achieving results. It is common to find general knowledge about
how large amounts of energy could be saved in a plant. The missing ingredient is the
discipline necessary to achieve these potential savings. Each step in saving energy needs to be
monitored frequently enough by the manager or first-line supervisor to see noticeable
changes. Logging of important fuel usage or behavioural observations are almost always
necessary before any particular savings results can be realized. Therefore, it is critical that an
energy director or committee have the authority from the chief executive to install controls,
not just advise line management. Those energy managers who have achieved the largest cost
reductions actually install systems and controls; they do not just provide good advice.
ORGANISATION STRUCTURE OF ENERGY MANAGEMENT PROGRAM:
The organizational chart for energy management program is shown in figure. It must be
adapted to fit into an existing structure for each organization. For example, the presidential
block may be the general manager, and VP blocks may be division managers, but the
fundamental principles are the same. The main feature of the chart is the location of the
energy manager. This position should be high enough in the organizational structure to have
access to key players in management, and to have knowledge of current events within the
company. For example, the timing for presenting energy projects can be critical. Funding
availability and other management priorities should be known and understood. The
organizational level of the energy manager is also indicative of the support management is
willing to give to the position.

Energy manager:
One very important part of an energy management program is to have top management
support. More important, however, is the selection of the energy manager, who can among
other things secure this support. The person selected for this position should be one with a
vision of what managing energy can do for the company.
Every successful program has had this one thing in common—one person who is a shaker and
mover that makes things happen. The program is then built around this person. There is a
great tendency for the energy manager to become an energy engineer. Developing a working
organizational structure may be the most important thing an energy manager can do.
Energy coordinators:
Energy Coordinators shall be appointed to represent a specific department or division. The
Energy Manager shall establish minimum qualification standards for Coordinators, and shall
have joint approval authority for each Coordinator appointed. Coordinators shall be
responsible for maintaining an ongoing awareness of energy consumption and expenditures in
their assigned areas. They shall recommend and implement energy conservation projects and
energy management practices. Coordinators shall provide necessary information for reporting
from their specific areas. They may be assigned on a full-time or part-time basis; as required
to implement programs in their areas.
Employees:
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Employees are shown as a part of the organizational structure, and are perhaps the greatest
untapped resource in an energy management program. A structured method of soliciting their
ideas for more efficient use of energy will prove to be the most productive effort of the energy
management program. A good energy manager will devote 20% of total time working with
employees. Too many times employee involvement is limited to posters that say “Save
Energy.” Employees in manufacturing plants generally know more about the equipment than
anyone else in the facility because they operate it. They know how to make it run more
efficiently, but because there is no mechanism in place for them to have an input, their ideas
go unsolicited. An understanding of the psychology of motivation is necessary before an
employee involvement program can be successfully conducted.
1) Initiating:
A well written energy policy authorized by the management provides the energy
manager with the authority of being involved in business planning, new facility
location and planning. Selection of production equipment, purchase of measuring
equipment and energy reporting.
The above mentioned policy confuses with a procedures manual,in order to
have an effective policy it should contain the planning
a) Objectives:
In this statements relating to energy and most importantly that the organization
will incorporate energy efficiency into facilities with an equipment must be
emphasised along with life cost analysis.
b) Accountability:
In this segment it should define the organization structure and authority held by
energy manager,coordinators etc.
c) Reporting:
For a smooth flow of an organization,metering the energy use with skilled labour
and instrumentation is must.Hence reporting provides a legitimate reason for
cancelling funds from top management
2) Planning:
Planning is the most important part of energy management program,and for most
technical people is the least desirable.From a good plan one can shield from

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disruption and also the scheduling of events puts continuous emphasis on the energy
management programme
a) Problem Definition
The problem is clearly defined all the members of energy management program
b) Grouping:
Divede large groups into smaller groups of seven to ten, then have group elected
recording secretary
c) Generation of Ideas:
Each person writes as many answers to a problem as can be generated within a
specifies time.
d) Round-Robin Listing:
Secretary lists each idea individually on a caset until all have been recorded.
Caset is a frame displaying charts,promotional materials etc.
e) Discussion:
Ideas are discussed for clarification,elaboration,evaluation and combiing
f) Ranking:
Each person ranks the five most important items.The total number of points
receive for eah idea will determine the first choice of group.
3) Educational or AuditPlanning:
Individual definitions of the audit contribute to the events that will keep energy
management programme active.For this to happen an audit team must be departed
such that
a) The team can be selected to match equioment to be audited, and thus can made as in-
house personnel
b) Energy team can identify all potential energy conservation projects, in terms of
capital investment the audit can be an excellent training tool by involving others in
process, and by adding a training component as a part of the audit
4) Reporting:
The bottom line is that any reporting system has to be customized to suit individual
circumstances and while reporting is not always the most crucial part of managing
energy, it can make a contribution to programme by providing bottom-line on it’s

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effectiveness. By making report of requirement of energy policy, it simply require
combining production data and energy data to develop an energy index.
With all the above considered, the best way to report is to do it against an audit than
has been performed at facility.
QUALITIES AND FUNCTIONS OF AN ENERGY MANAGER:
Energy managers can come from a variety of backgrounds, since energy is a multi-
disciplinary specialty. It is difficult to lay down hard and fast rules about the qualities required
for an energy manager. Generally, the energy manager will be drawn from the existing
workforce. Since, he should be thoroughly familiar with the whole range of organizations
activities from input to output of the process and finance. The energy managers should have
the ability and open-mindedness to keep abreast of the latest developments in energy
efficiency technology. The energy manager may also be an external person, appointed,
considering his experience and expertise in the relative field of the process involved. There is
no precise blueprint for a successful energy manager and the job is also not clearly defined.
• The energy managers should have high visibility within the organization.
• They have more responsibility to get the job done with very less authority. They need
a good grasp of both the design aspects and nuts/bolts details of conservation
programmes i.e., they should have a thorough understanding of the company's
process, products, maintenance procedures and facilities.
• A good energy manager should be able to communicate clearly and persuasively with
lawyers, engineers, accountants, financial planners, public relation specialists,
government officials etc., in their own language.
• To have a continuous support of top management, the energy manager has to develop
and present his programme and investment with predictable returns instead of
unrecoverable costs.
• The energy manager should control and coordinate the conservation campaigns.
• He should control his area of responsibility very efficiently.
• He must be capable of directing all the personnel involved in consuming the supply
of energy for which he is responsible.
• He has to decide regarding investment in a particular project analyzing the costing
techniques.

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The role of the energy manager discusses direct access to senior management and
their full support and commitment and answers the questions like:
(i)
(ii)
(iii)
Who should be appointed?
What benefits will an energy manager bring?
How does he fit into the company's structure?
An important concept to energy manager is efficiency. Losses some of which are
thermody-namically unavoidable and some are economically irretrievable, contribute to
inefficiency. The challenge to energy manager is to first identify those which he can do
something about, find how to do it, and then get the management agree to do it.
He needs a questioning mind and should possess the ability to command the support
of colleagues.
The terms of reference of the energy manager should be clearly defined i.e., whether
he has an authority within a service or production department or whether he acts only in an
advisory and coordinating role. Based on the type and size of the organization, the duties of
energy manager should include any/all of the following:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
(vii)
(viii)
To generate interest in energy conservation and to sustain the same with new ideas
and activities and for lecturing training courses.
To ensure that the records and accounting system are maintained in consistent
units and are uniform.
To give technical advice on energy saving techniques and equipment.
To identify the sources of technical guidance.
To coordinate the efforts of all energy users and set realistic targets.
To maintain essential records of purchases, stock, consumption reviewing the
energy utili-zation performance periodically, watching the trends and to advice the
senior management.
To identify the source of energy wastage, quantify the wastage or losses in
financial terms and suggest practical recommendations to reduce these losses.
To identify areas requiring deep study, maintain records of such in-depth studies
and to review the progress.
(ix) To provide material of good energy practice to suit the needs of the organization.
(x) To give special advices, with due consideration to energy conservation, safety and
healthy aspects, to various departments of the organization.

EACM 23
(xi) To keep track of all the significant developments in the field of energy
conservation by maintaining contact with appropriate research organizations.
To advise the senior management on matters of energy with latest developments
in the global scenario.
(xii)
For a successful energy manager, the following points may be considered as guidelines:
1.Based on factual data prepared, think ahead, anticipating questions; the request for approval
of expenditure is to be made sufficiently in advance.
2. Learn how to say 'NO' in a diplomatic way and be aggressive.
3. Stick your neck out as energy is not a safe sell.
4. Be creative; put the action plan tasks on priority after identifying the needs.
5. Be a good and patient listener and establish a free thinking environment.
6. Prepare and develop implementation strategies.
7. Establish credibility through an accurate energy accounting system.
8. Be patient but demanding as efficient use of energy is an evolutionary process.
LANGUAGE OF THE ENERGY MANAGER:
It is essential to understand the language of the energy manager and how it is applied
to facilitate easy communication of energy conservation goals and to analyze the literature in
the field. For the better comparison of efficiencies of various fuels and the cost per unit
heating value, it is essential that the heating value of each fuel is expressed in proper units,
i.e., Btu, Kcal, KJ. The method of reducing the energy cost of the plant can be easily
understood and analyzed only when the energy contents of the plants processes is known. If
the energy is utilized efficiently, definitely there will be reduction in product costs and
increase in profits. This requires the preparation of the energy balance for the plant during a
given period. Energy managers need to make forecasts as to the availability of supplies, fuel
pricing and the future energy use of their building companies. Only after knowing all the
facts, engineering judgment can be made and conclusions drawn. Unfortunately, with energy
forecasting, not all the facts are known and many times conflicting data exist. For the
development of a good forecasting model, the energy manager should know past and present
consumption of energy and the pricing pattern.

EACM 24
Questionnaire-Check list for Top Management
Control of Energy
a) Name, Status and Qualification of person responsible for energy management
b) Energy consumption should be reviewed regularly and a detailed energy
consumption analysis undertaken.
c) Units of measurement and possible rationalization of energy data into one unit
other than money.
d) Metering facilities should be available for motoring fuels, keeping records and
budgeting
e) Fuel consumption should be compared with previous figures and management
should set targets.
f) Energy Education, information, energy recycling schemes, planned maintenance
and regular testing of energy plant
g) List of Energy Saving Projects in order of priority with costs and pay back
calculation.
h) Energy flow diagram
Sources of Energy:
a) Energy Sources used by the company i.e. solid fuels, gas, electricity, liquid fuels
others
b) List of Tariffs use
Use of energy:
a) Buildings should be considered with respect to insulation, Heating periods,
manuals or automatic Heating control of temperature and ventilation.
b) Storage Tanks: Heating, Insulation
c) Ares of High energy Consumption
d) Process: lagging of pipes and tanks, boiler and furnace efficiency testing,
condensate recovery, process temperature levels.

EACM
1
UNIT2:
LIGHTING
Existing Systems
The existing lighting systems consists of single and double florescent lighting units
mounted within a suspended ceiling grid. In some locations lighting level (Lux) readings are as
low as 115 Lux, close to the limits of acceptability. It is certainly less than ideal in relation to the
following factors:
1. Lamp Maintenance factor:
The florescent tubes have a life expectancy of 5000 hours however their output
decreases as they age by up to 50% within the first year. Fluorescent tubes should be
changed every year.
2. Flicker:
Some fluorescent tubes can flicker noticeably and produce an uneven light that may
have a strobe light effect and will bother some users. Once the flicking becomes obvious
to the eye, there is no choice but to replace the lamp. They also generate some
background noise and are some users can be sensitive to this. In addition the
overall Lux(illumination) levels are quite low and thus lighters and/or desk lamps are
used to supplement the light levels delivered at the working plane. This adds to the
overall electricity usage and costs.
3. Light Distribution and Uniformity:
The current diffusers in the lighting units are "CATII type" and were initially designed
to be used to reduce lighting reflection on monitor screens. Unfortunately this style of
fluorescent light diffuser panel can produce a gloomy environment if used on its own
and reduces the light distribution and uniformity.
These diffusers are open and hence dirt collects on the diffuser and lamp, which also
reduces the effectiveness of the lamp.
4. Current lamp efficiency:
The current lighting units mainly consist of single and/or double 1500mm long "T8" 58
watt fluorescent tubes. Due to the power units and chokes required to drive the lighting
units, the light fittings actually rate as 70watts each.

Criteria for Proposed Replacement units
1. Extensive research has been carried out by Property Services to find a suitable Light-
emitting diode lamps (LED) lighting unit to replace the current lights within the Whit field
Office complex.
2. To warrant replacement on the scale proposed on economic grounds it is necessary for the
scheme to have a payback period of between 5 and 10 years. For such a pay-back period to
be feasible it was necessary for any proposed new lighting units to be:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
(vii)
Purchased a minimum cost.
Improve light output at the working plane but at a significant energy saving.
Simple to install so that they could be installed by Civic Wardens with
minimum disruption to staff.
Capable of installation without the need to carry out modification to the existing
wiring circuitry.
Capable of installation without the need to modify the ceiling grid.
Provide an even distribution and uniform light at the working plane.
Reduce lighting unit life costs (maintenance)
Trials have been undertaken within the Council's Offices using "off the shelf lighting units
obtained from leading lighting manufactures and suppliers. These manufactures also supplied
feasibility schemes together with costings, which were considered to determine the most
appropriate lighting unit and manufacturer.
DEFINITIONS
PLANE ANGLE: An angle formed by two straight lines in the same plane.
SOLIDANGLE: An angle having a value equal to the area on a sphere subtended by a surface,
divided by the square of the radius of that sphere. Solid angles are measured in steradians.
LIGHT: Radiant energy in form of waves which produces a sensation of vision upon the human
eye.
LUMINOUS FLUX: It is defined as the energy in the form of light waves radiated per second from
a luminous body. Its unit is lumen. It is denoted by ∅=𝑄
𝑡
LUMEN: Luminous flux emitted by a source of one candle power in a unit solid angle.
EACM
2

EACM
3
ILLUMINATION OR LUMINANCE: Luminous flux falling on unit area. Unit is lumens/m2 or lux.
The british unit is lm/ft2 or foot candle (fc).
LUX: Luminous flux per unit area. It is equal to one lumen per square metre.
LUMINOUS INTENSITY: It is the light emitting power of the lamp. The luminous flux emitted per
unit solid angle.
CANDLE POWER: Number of lumens emitted by the source per unit solid angle in a given
direction.
(Or)
The luminous intensity of a standard candle of surface area 1/6000,000 m2 at the temperature of
freezing platinum under a pressure of 101325 N/ m2 in a perpendicular direction is one candla.
LUMINOUS EFFICIENCY: It is the ratio of energy radiated as light to the total energy radiated.
Luminaire: Luminaire is a device that distributes filters or transforms the light emitted from one
or more lamps. The luminaire includes, all the parts necessary for fixing and protecting the
lamps, except the lamps themselves. In some cases, luminaires also include the necessary circuit
auxiliaries, together with the means for connecting them to the electric supply. The basic
physical principles used in optical luminaire are reflection, absorption, transmission and
refraction.
Ballast: A current limiting device, to counter negative resistance characteristics of any discharge
lamps. In case of fluorescent lamps, it aids the initial voltage build-up, required for starting.
Ignitors: These are used for starting high intensity Metal Halide and Sodium vapour lamps.
Illuminance: This is the quotient of the illuminous flux incident on an element of the surface at
a point of surface containing the point, by the area of that element. The lighting level produced
by a lighting installation is usually qualified by the illuminance produced on a specified plane. In
most cases, this plane is the major plane of the tasks in the interior and is commonly called the
working plane. The illuminance provided by an installation affects both the performance of the
tasks and the appearance of the space.
Luminous Efficacy (lm/W):
This is the ratio of luminous flux emitted by a lamp to the power consumed by the lamp. It is a
reflection of efficiency of energy conversion from electricity to light form.

Color Rendering Index (RI): Is a measure of the degree to which the colours of surfaces
illuminated by a given light source confirm to those of the same surfaces under a reference
illuminent; suitable allowance having been made for the state of Chromatic adaptation
SPACE-HEIGHT RATIO: Ratio of horizontal distance between the adjacent lamps and height of
their mountings. The space-height ratio should be taken up as 1.5 to get proper distribution of
light below the lamp on the working plane.
DEPRECIATION FACTOR: It gives a measure of reduction in the light output after the lamps have
deteriorated and the fittings have become dirty. Depreciation factor is used because an
installation gives only a fraction of the illumination it would give when perfectly clean.
MAINTENANCE FACTOR: It is the inverse of the depreciation factor.
COEFFICIENT OF UTILIZATION OR UTILIZATION FACTOR: This factor gives a measure of the
losses. The losses may be due to absorption of light by walls, floor, ceiling, equipment, furniture,
etc.
REFLECTION FACTOR: It is the ratio of the reflected light to the incident light.
BEAM FACTOR: It is the ratio of lumens in the form of a projection to the lamp lumens. It
takes into consideration the absorption of light by reflectors and front glass of the lamp. It lies
between 0.3 and 0.6
MEAN SPHERICAL CANDLE POWER (MSCP): It is the average of the candle powers in all
directions in all planes, given by MSCP= Total luminous flux in lumens/4𝜋
MEAN HEMISPHERICAL CANDLE POWER (MHSCP): It is the average of the candle powers in
all directions in all planes, given by MHSCP= Total luminous flux in lumens/2𝜋
MEAN HORIZONTAL CANDLE POWER (MHCP): It is the average of the candle powers in all
directions on horizontal plane which passes through the source.
Ruction factor= 𝑀
𝑆𝐶
𝑃
𝑀𝐻𝐶
𝑃
Lumens required from lamps=
𝑙
𝑢
𝑚
𝑒
𝑛
𝑠𝑜
𝑛𝑤
𝑜
𝑟
𝑘
𝑖
𝑛
𝑔𝑝
𝑙
𝑎
𝑛
𝑒
𝑢
𝑡
𝑖
𝑙
𝑖
𝑧
𝑎
𝑡
𝑖
𝑜
𝑛𝑓
𝑎
𝑐
𝑡
𝑜
𝑟
∗
𝑚
𝑎
𝑖
𝑛
𝑡
𝑒
𝑛
𝑎
𝑛
𝑐
𝑒𝑓
𝑎
𝑐
𝑡
𝑜
𝑟
GLARE: If the eye is exposed to a very bright source of light, the pupil or opening of the eye
contracts in order to reduce the amount of light admitted and prevents the damage of the
retina. This reduces the sensitivity of the eye to see perfectly other objects within the field of
the vision. This phenomenon is glare.
EACM
4

LUMINOUS EFFICIENCY
As shown in fig known as spectral distribution curve, suppose E is the energy radiated on a
wavelength of  ,and the sensitivity of the eye to colour at this wavelength is K  ,then the
energy content of the waves between  and  +d  is E d  , where d  where is an
infinitesimal increment in the wavelength. The visual effect of this energy will be 670 K  E d
.
Integrating between two finite wavelength, 1 and, 2 the visual effect will be
2
670 K Ed lm
1
The total energy radiated by all wavelengths of light is the energy input to the lamp.

E d Ws
0
Therefore luminous efficiency of a source of light is defined as
EACM
5

2 
lu min ous  (670 K E d )/( E d )
1 0
Polar Curve
In most lamps the luminous intensity is not the same in all directions. Suppose that the lamp is
held with its vertical and the luminous intensity is measured in all directions on a horizontal
plane, through the lamp. The curve of intensity in candle power against direction is plotted as
shown in Fig, which shows the horizontal polar curve of a gas-filled lamp with a horizontal
circular element. The drop in candle power along OA' is due to the break in the ring where the
current enters and leaves. The sensitivity of the eye to color at this wavelength is mean of the
candle power in this curve gives the mean horizontal candle power (MHCP), and is found by
taking the moan at the angular positions, 0, 10°, 20°, .... 350°. The luminous intensity (or candle
power) in any given direction is measured by theBunsen Photometer.
The mean spherical candle-power (MSCP) is the mean of the candle power in all
directions radiating from the lamp, and is the total flux divided by 4  . It would be
very difficult to measure the candle power in all directions and take the mean.
Reduction factor=MSCP/MHCP
EACM
6

Calculation of illumination level
The illumination at a point on a surface is defined as the luminous flux per unit area at that point,
the value being expressed as lumens per square meter or lumens per square foot. An illumination
of 1 lm/m 2
.
Suppose that a standard candle power of I cd is situated at O and the narrow cone is along the
horizontal direction, so that the luminous flux in this cone of solid angle S is S*I lumens. The
luminous intensity at any point on the cone is SI lumens per S steredians, or I lumens per
steradian. The illumination at any point of the cone, at a distance r from O is
Fig. Solid angle
lm/ area
area
SI
E 
Since the solid angle is S, the area a= Sr2
, so that the illumination is
r2
SI
Sr2

I
lm / area
E 
r2
I
The illumination is lux if r is in metres or
I
r2
fc if r is in feet. Thus, the illumination varies as
the inverse square of the distance from the diverging source, but the luminous intensity is
constant along a fixed direction. This it is known as the inverse square law and is widely used in
calculation of illumination.
Illumination of an Inclined Surface to Beam
In the previous section it was assumed that the surface upon which light was falling was at
right angles to the axis of the beam, but in practice this is not usually the case,and the
EACM
7

conditions are then as shown in fig.. If a small element of the beam inclined at an angle to the
vertical is considered, the illumination on a surface, such as AB at right angles to the beam
axis can easily be calculated from
I
b2
E 
If, however, we consider the horizontal surface CD, it is evident that the total number of
lumens falling on this is the same as on AB. It can be seen, however, that the area of this
surface CD will be equal to area of AB/cos 
Let the area of AB=a=Sb2
Where S=solid angle subtended by AB at 0
Area of CD=a/cos = Sb2
/cos
Lumens emitted by source of candle power I is SI
Therefore, illumination becomes
cos
b2

I
cos
Sb2
SI
E 
Since b can be expressed as
b=r/cos
where r=height of O above the plane
r2
E 
I
cos3

EACM
8

TYPES OF LIGHTING SCHEMES:
1. Direct Lighting:
 The light falls directly on the object to be illuminated.
 It is most efficient but causes hard shadows and glare.
 The possibilities which will glare on eyes have to be eliminated while designing.
 A correct size of lamp with suitable fitting should be selected.
 The fittings are should to be cleaned regularly as the dirt if accumulated will decrease the
luminous intensity.
 It is used for industrial and general outdoor lighting.
2. Indirect Lighting
 The light does not fall directly on the object.
 Light is thrown to the ceiling for diffuse reflection from where it reaches the object.
 The ceiling acts as the light source and the glare is to minimum.
 The resulting illumination is softer and more diffused the shadows are less promiinent
and the appearance of room is much improved as compared to direct lighting.
 The requirement of the light is usually more than direct lighting.
 It is used for decoration of purposes in cinemas theatres, hotels etc
3. Semi - Direct Lighting :
 60% of the light is directed down wards and 40% projected upwards
 It is suitable to rooms with high ceilings where high level of uniformly distributed
illumination is desirable.
 Glare can be avoided by employing diffusing globes
 They improve the brightness towards the eye and efficiency of the system
4. Semi Indirect Lighting :
 60 to 90% of total light flux is thrown upwards to the cieling for diffuse reflection
and the rest i.e. 40 to 10% reaches the working plane directly.
EACM
9

 It gives soft shadows and it is glare free.
 It is used for indoor light purposes.
5. General Lighting:
 It produces equal illumination in all directions.
 It gives soft light with little shadows.
 Since quite large amount of light reach objects after reflection from walls and
ceiling, room decoration should be in light colours and kept in good condition.
 The mounting height should be much above eye level to avoid glare.
TYPES OF LAMPS
Incandescent Lamps
 Incandescent bulbs are the original form of electric lighting and have been in use for over
100 years.
 They are made in an extremely wide range of sizes, wattages, and voltages.
 Works on the principle of incandescence which is the emission of light caused by heating
the filament
 An incandescent bulb consists of a glass enclosure containing a tungsten filament.
 An electric current passes through the filament, heating it to a temperature that produces
light.
 They contain a stem or glass mount attached to the bulb's base which allows the electrical
contacts to run through the envelope without gas/air leaks.
 Small wires embedded in the stem support the filament and/or its lead wires.
 The enclosing glass enclosure contains either a vacuum or an inert gas to preserve and
protect the filament from evaporating.
EACM
10

Diagram showing the major parts of a modern incandescent light bulb.
1. Glass bulb
2. Inert gas
3. Tungsten filament
4. Contact wire (goes to foot)
5. Contact wire (goes to base)
6. Support wires
7. Glass mount/support
8. Base contact wire
9. Screw threads
10. Insulation
11. Electrical foot contact
Incandescent bulbs require no external regulating equipment, have a very low manufacturing
cost, and work well on either alternating current or direct current. They are also compatible with
control devices such as dimmers, timers, and photo sensors, and can be used both indoors and
outdoors. As a result, the incandescent lamp is widely used both in household and commercial
lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for
decorative and advertising lighting.
EACM
11

FLUORESCENT LAMP
These lamps are hot cathode low pressure mercury vapour lamp and are manufactured in form of
long glass tubes.
Construction:
 It consists of tube with two electrodes. They are coated with electron emissive material.
 It contains a small quantity of argon gas at a pressure of 2.5 mm of mercury and a few
drops of mercury.
 The inside surface of the tube is coated with a thin layer of fluorescent powder material
known as phosphor. The phosphor used for coating depends upon the color required.
 A starter is present in the circuit. It connects the electrodes directly across the supply at
the time all starting.
 A choke is connected in series with the electrodes. It provides a voltage impulse at the
time of starting and acts as ballast during running.
Working:
 When the supply is given, the full voltage appears across starter terminals as the
resistance of the electrodes is very less.
 As the starter is filled with argon gas, it ionises and glow appears inside the starter. So the
bimetallic strip in the starter is heated up and short circuits the starter. So maximum
current flows through the electrodes and choke.
 Due to flow of current, the electrodes get heated up and start emitting electrons.
Gradually, the potential across the starter falls to zero and cools down bimetallic strip
resulting in the opening of starter terminals.
 This sudden opening of the starter terminals results in abrupt change of current (di/dt) in
choke.
EACM
12

EACM
13
 Since electrons are already present in the discharge tube, this induced voltage is sufficient
to breakdown the long gap thus resulting in the flow of electrons between the electrodes.
 The electrons while accelerating, collide with argon and mercury vapour atoms. The
excited atoms of mercury give UV radiation.
 If this radiation is made to strike with phosphor material it produces re-emission of light
radiation of different wavelength and results illumination. This phenomenon of re-
emission is called flourescence and hence it is named as fluorescent tube.
 The average life of fluorescent lamp is 4000 - 5000 hours and its efficiency is about 40
lumen/watt. These lamps operate at low p.f. hence capacitor should be used.
Advantages:
 High luminous efficiency
 Long life
 Low running cost
 Low glare level
 Less heat output
Disadvantages:
 Stroboscopic effect
 Small wattage requiring large number of fittings.
 Magnetic hum associated with the choke causing disturbance
Stroboscopic effect:
Fluorescent lamps are provided with 50Hz or 60Hz ac current supply. When operating under the
frequencies the lamp crosses zero wave double the supply frequency, i.e, 100 times for 50Hz
frequency and 120 times for 60Hz frequency per second. Due to the persistence of vision our
eyes do not notice them. However if the light falls on the moving parts due to illusion, they may
appear to be either running slow, or in reverse direction or even may appear stationary. This
effect is called "Stroboscopic effect".

Methods to Avoid:
This pattern of illusions is not allowed in industries as this may lead to accidents. This is the
main reasons Fluorescent lamps are not preferred in industries. However this effect can be
avoided by:
 If the industry is supplied with three phase supply, adjacent lamps should be fed with
different phase so that the zero instants of the two lamps will not be same.
 If single phase supply is only available, then connection of two adjacent lamps are made
such that the two lamps are connected in parallel with the supply and in one lamp
connection a capacitor or condenser is kept in series with the choke. This makes a phase
shift thereby eliminating stroboscopic effect
SODIUM VAPOUR LAMPS
A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce
light. A sodium vapour lamp is also a cold cathode low pressure lamp which gives luminous
output about three times higher other lamps.
Construction:
 It consists of an inner tube made of special glass to withstand high temperature of electric
discharge.
 It consists of two electrodes connected to a pin type base.
 The tube is filled with sodium and a small amount of neon at a pressure of 10 mm of Hg.
EACM
14

EACM
15
 Neon helps to start the discharge and the heat developed helps to vaporize sodium.
 The lamp operates at 300 °C. Any change in the operating temperature will affect the
light given by the lamp. So the U-shaped tube is enclosed in an outer double walled glass
tube.
 Before sealing the lamp, vacuum is created between the double walled glass tubes.
Working:
 When supply is given, the discharge is initiated through neon gas which produces reddish
light.
 When cold sodium is in solid state and hence the lamp cannot be started as sodium
vapour lamp.
 After sometime as the temperature gradually increases due to the discharge by neon gass,
the solid sodium turns into vapour giving yellowish light.
 If switched off, it can be restarted immediately.
 The luminous efficiency of lamp is 40-50 lumen/watt. The life is approximately 3000
hours
Advantages:
 Most of the radiation is on visible region hence the efficiency is good.
 Excitation level is achieved with low voltage and requires less energy compared to other
vapors.
Disadvantages:
 It gives monochromatic orange-yellow light which makes the object appear as grey.

High Pressure Mercury Vapour lamps
It is a hot cathode (filament is used to heat the electrode) gas discharge lamp.
Construction:
 It consists of two main electrodes of tungsten coated with barium oxide enclosed in hard
glass tube made of borosilicate or quartz.
 There is an auxiliary starting electrode near one of the main electrode and the tube
contains argon gas at low pressure and some mercury.
 The inner tube or bulb is enclosed in another glass bulb and space between the two tubes
or bulbs is either partially or completely filled with vacuum prevent heat loss.
 The lamp has a screwed cap and is connected to choke coil having different tappings in
series with lamp to give high starting voltage for discharge and controlling the current
and voltage across the lamp after discharge.
 The p.f of the circuit is low due to choke coil. It can be improved by installing a
condenser parallel to supply line.
Working:
 When the supply is given, the current does not flow through main electrodes due to high
resistance of the gas.
EACM
16

EACM
17
 The current starts to flow between the main electrode and auxiliary electrode through
argon gas.
 The heat thus produced vaporize mercury which reduces the resistance between the
electrodes.
 Due to low resistance ionised path between two main electrodes the discharge shifts from
auxiliary electrode circuit to main electrodes.
 Mercury vapor lamp gives 2.5 times higher light than incandescent lamp for same power
consumption.
 The life is approximately 3000 hrs and it gives illumination bluish color.
 The efficiency of the lamp is 35-40 lumens per watt are specially used for high way
lighting, park lighting etc.
Advantages:
 The life of mercury vapor lamp is much higher than incandescent lamp.
Disadvantages:
 It takes about 4-6 minutes to give full brilliance.
 The original color of the object cannot be judged.
 It takes 6 A approximately on first switching ON and after six minutes if falls to 3 A.
 It cannot be used in any standard lamp holder as there are three pins in its cap.

CFL Lamps
Principle of Operation
The electronic ballast circuit block diagram includes the AC line input voltage (typically 120
VAC/60 Hz), an EMI filter to block circuit-generated switching noise, a rectifier and smoothing
capacitor, a control IC and half-bridge inverter for DC to AC conversion, and the resonant tank
circuit to ignite and run the lamp. The additional circuit block required for dimming is also
shown; it includes a feedback circuit for controlling the lamp current.
EACM
18

CFL electronic ballast block diagram
The lamp requires a current to preheat the filaments, a high-voltage for ignition, and a high-
frequency AC current during running. To fulfill these requirements, the electronic ballast circuit
first performs a low-frequency AC-to-DC conversion at the input, followed by a high-frequency
DC-to-AC conversion at the output.
The AC mains voltage is full-wave rectified and then peak-charges a capacitor to produce a
smooth DC bus voltage. The DC bus voltage is then converted into a high-frequency, 50% duty-
cycle, AC square-wave voltage using a standard half-bridge switching circuit. The high-
frequency AC square-wave voltage then drives the resonant tank circuit and becomes filtered to
produce a sinusoidal current and voltage at the lamp.
When the CFL is first turned on, the control IC sweeps the half-bridge frequency from the
maximum frequency down towards the resonance frequency. The lamp filaments are preheated
as the frequency decreases and the lamp voltage and load current increase.
EACM
19

CFL operation timing diagram
The frequency keeps decreasing until the lamp voltage exceeds the lamp ignition voltage
threshold and the lamp ignites. Once the lamp ignites, the lamp current is controlled such that the
lamp runs at the desired power and brightness level.
To dim the fluorescent lamp, the frequency of the half-bridge is increased, causing the gain of
the resonant tank circuit to decrease and therefore lamp current to decrease. A closed-loop
feedback circuit is then used to measure the lamp current and regulate the current to the dimming
reference level by continuously adjusting the half-bridge operating frequency.
Types of Lighting
A lighting installation may be classifies into four main groups:
1) General
2) Angle
3) Localized
4) Local
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1) General Lighting
This is a system in which each part of an area is illuminated from a number of fittings in
different directions, resulting in a fairly uniform distribution of illumination throughout the
area. It is generally provided by a number of fittings symmetrically arranged over the area.
Adequate wall lighting is advisable to provide bright surroundings, if the light is concentrated
too much in a downward direction, or if the lamps are fitted too low, the walls will be less
lighted. The light from one fitting should overlap that of the next fitting, consequently
increase of the mounting height of the lamps enables them to serve a larger area and widens
the possible lamp spacing, Minimum/maximum illumination ratio in the area should be about
70 per cent if possible. A large proportion of the light received at a given point will reach that
point by reflection from the walls, especially if these are bright. Surfaces absorb some of the
light received by them, consequently the total amount of light received by a surface will
depend to some extent on the area of walls illuminated. This factor tends to reduce the
efficiency of a system of general lighting with an increase of fitting height. The degree to
which light received by the walls is reflected back depends on the nature and finish of the
wall surfaces. The utilization factor depends on this effect.
2) Angle Lighting
This may be necessary for purposes such as the provision of good lighting on vertical
surfaces, avoidance of shadows, or the creation of shadows for some specific purposes. It
may be affected by using a concentrated source of light, such as spotlight, or by using a wide
angle or parabolic reflector.
3) Localized Lighting
This may be adopted to give a relatively higher degree of illumination in the work area, with
appreciably less light in the surrounding area. Tubular fluorescent lamps are particularly
suitable for such purposes.
4) Local Lighting
This is frequently necessary to supplement general lighting where a very high degree of
illumination is needed over a small working area, such as the cutting tool of a lathe.

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Electric Lighting Fittings (Luminaire):
In general, an electric lamp and its fitting (globe, reflector, etc.) should be regarded as in
integral whole, i.e., the lighting "unit" consists of the lamp and fitting, each designed to suit
the other and to give the desired distribution of light. There are five main groups of fittings as
given below: (1) Direct (2) Semi-direct (3) General (4) Semi-indirect (5) Indirect.
Direct Fittings:
These emit not less than the 70 percent of the total light flux of the lamp and fitting in the
lower hemisphere. The dispersive type reflectors are useful for industrial interiors where
highly polished materials are not worked. Direct light is cut off at an angle of 20 degrees
below the horizontal, maximum illumination being given on tie horizontal plane. If desired
the reflector may have a cover of clear to frosted glass. The height of the lamps should be
about two thirds of the lamp spacing, these fittings provide fair illumination on a vertical
plane.
The industrial diffusing fitting, with an enclosed diffusing bowl of opal glass, is suitable for
works and offices where there is risk of glare in direct or indirect light. Lamp consumption is
rather high with the diffusing fitting than with the standard disruptive reflector, but as the
ceiling receives more light, the appearance of the room may be improved.
The concentrating reflector is most useful for high mounting, such as high bay foundries, and
for overhead travelling cranes. Most of the light is concentrated into the 0 to 30 degrees
region, the cut-off angle being about 30 degrees. A clear or frosted dustproof cover glass may
be fitted
Semi Direct Fittings
These give between 50 and. 70 percent of the, total light flux in the lower hemisphere. The
fittings may be made of prismatic or of opal glass, or of glass and metal, and are suitable for
utility lighting of offices and shops.
General Lighting Fittings

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Opal or prismatic varieties of glass are useful for the general lighting of shops, offices, and
similar interiors. They emit 40 to 45 per cent of the total light flux in either hemisphere. This
type allows more light to reach the ceiling than in the semi direct fitting. The spacing/height
ratio may be about 1.25 to 1. The surface brightness should not exceed 1 candle per sq. cm if
glare is to be avoided. This fitting gives a very pleasing effect with soft shadows.
Semi Indirect Fittings
These give 40 to 45 per cent of the total light flux in the upper hemisphere, and may be made
of opal, frosted, or prismatic glass, or glass and metal. They require a higher wattage than the
direct type of fittings, but give little shadow or risk of glare. Thr.:e fittings are very suitable
for high class utility lighting such as offices, board rooms, etc., having light coloured
ceilings.
Indirect Fittings
These emit not less than 70 per cent of their light in the upper hemisphere. With such fittings
it is essential that the ceilings and upper walls be of very light colour, in which case good
illumination, free from shadows, can be achieved. The fitting requires high wattage and
frequent cleaning and is not advised where an extremely high degree of illumination is
required. It is suitable for shops
Flood Lighting
Another application of illumination engineering is flooding of light overlarge surfaces in open
air. This is carried out by means of a projector/reflector for several purposes:
1. Aesthetic flood lighting—For enhancing the beauty of a buildingby night, e.g., churches,
towers and monuments.
2. Advertising — Flood lighting of commercial buildings.
3. Industrial — Flood lighting of railway yards, quarries, sports areas, etc. Arc lamps were
previously used in projection lanterns for flood lighting. Nowadays special lamps having
bunched filaments are used with projectors.

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White Light LED
A light emitting diode (LED) is known to be one of the best optoelectronic devices out of the
lot. The device is capable of emitting a fairly narrow bandwidth of visible or invisible light when
its internal diode junction attains a forward electric current or voltage. The visible lights that an
LED emits are usually orange, red, yellow, or green. The invisible light includes the infrared
light. The biggest advantage of this device is its high power to light conversion efficiency. That
is, the efficiency is almost 50 times greater than a simple tungsten lamp. The response time of
the LED is also known to be very fast in the range of 0.1 microseconds when compared with 100
milliseconds for a tungsten lamp.
We know that a P-N junction can connect the absorbed light energy into its proportional electric
current. The same process is reversed here. That is, the P-N junction emits light when energy is
applied on it. This phenomenon is generally called electroluminance, which can be defined as the
emission of light from a semi-conductor under the influence of an electric field. The charge
carriers recombine in a forward P-N junction as the electrons cross from the N-region and
recombine with the holes existing in the P-region. Free electrons are in the conduction band of
energy levels, while holes are in the valence energy band. Thus the energy level of the holes will
be lesser than the energy levels of the electrons. Some part of the energy must be dissipated in
order to recombine the electrons and the holes. This energy is emitted in the form of heat and
light.
The electrons dissipate energy in the form of heat for silicon and germanium diodes. But in
Galium- Arsenide-phosphorous (GaAsP) and Galium-phosphorous (GaP) semiconductors, the
electrons dissipate energy by emitting photons. If the semiconductor is translucent, the junction
becomes the source of light as it is emitted, thus becoming a light emitting diode (LED). But
when the junction is reverse biased no light will be produced by the LED, and, on the contrary
the device may also get damaged.
The constructional diagram of a LED is shown below.

Advantages of LED’s
 Very low voltage and current are enough to drive the LED.
 Voltage range – 1 to 2 volts.
 Current – 5 to 20 milliamperes.
 Total power output will be less than 150 milliwatts.
 The response time is very less – only about 10 nanoseconds.
 The device does not need any heating and warm up time.
 Miniature in size and hence light weight.
 Have a rugged construction and hence can withstand shock and vibrations.
 An LED has a life span of more than 20 years.
Disadvantages
 A slight excess in voltage or current can damage the device.
 The device is known to have a much wider bandwidth compared to the laser.
 The temperature depends on the radiant output power and wavelength.
A mix of red, green and blue LEDs in one module according to the RGB colour model,
white light is produced by the proper mixture of red, green and blue light. The RGB white
method produces white light by combining the output from red, green and blue LEDs. This is an
additive colour method
Conducting Polymers:
Conductive polymers or, more precisely, intrinsically conducting polymers (ICPs) are organic polymers that
conduct electricity. Such compounds may have metallic conductivity or can be semiconductors. The biggest
advantage of conductive polymers is their process ability, mainly by dispersion. Conductive polymers are
generally not thermoplastics, i.e., they are not thermo formable. But, like insulating polymers, they are
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organic materials. They can offer high electrical conductivity but do not show similar mechanical properties to
other commercially available polymers. The electrical properties can be fine-tuned using the methods of organic
synthesis and by advanced dispersion techniques.
Due to their poor processability, conductive polymers have few large-scale applications. They
have promise in antistatic materials and they have been incorporated into commercial displays
and batteries, but there have had limitations due to the manufacturing costs, material
inconsistencies, toxicity, poor solubility in solvents, and inability to directly melt process.
Literature suggests they are also promising in organic solar cells, printing electronic circuits,
organic light-emitting diodes, actuators, electro chromism, super capacitors, chemical sensors
and biosensors, flexible transparent displays, electromagnetic shielding and possibly replacement
for the popular transparent conductor indium tin oxide
Energy Conservation Measures:
1. Design, installation, and operation of effective lighting systems have complex
scientific,management, engineering, and architectural considerations. Of the many elements that
must be considered in providing an adequate visual environment of acceptable cost, energy
conservation is only one. Other elements that must be taken into account are the visual tasks to
be performed, the psychological state and perceptual skill of the observer, the design of task and
surrounding areas the availability of daylight, the level of illumination and the lighting system
quality with regard to spectral characteristics, glare, reflections and geometrical factors. These
complexities limit the degree to which simple guidelines for energy conservatior in lighting can
be applied in all cases. However, in most situations they are very useful in providing the
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guidance necessary to achieve substantial savings in lighting energy and cost while also
providing an adequate visual environment.
2.In the design of new lighting systems modifying existing ones, the most efficient light sources
tha can provide the illumination required should be selected. As a general rule, the efficiencies of
some available lamp types rank according to the following list, with the most efficient given
first, (a) high pressure sodium vapour, (I)) fluorescent (c) mercury, and (d) incandescent. Many a
replacement of the existing low efficiency lamp types with lower voltage more efficient types
will result in reduced total costs and improved lighting. See Table for detailed example.
3.Maximum control over lighting systems can be accomplished by using switches to control the
turning off of unnecessary lighting. Large general areas should not be under the exclusive control
of a single switch, if turning off small portions would permit substantial energy savings when
they are not occupied. Lights should be turned off as a regular practice when buildings are not
occupied, such as after working hour’s or on weekends and holidays. When opportunities for
existing daylight exist, lights could be turned off. Occupants of buildings should be educated and
periodically reminded to adopt practices which will save lighting energy, such as turning off
lights when leaving a room.
Frequent switching on or off of a lamp shortens its life. Therefore, there is an optimum point
between energy cost savings and the cost of lamps and replacement labour. Variations in energy
prices, labour costs, and convenience influence the decision. However, under typical working
conditions the break-even point for fluorescent lamps is reached in five to ten minutes where
replacement costs are low and in 20 to 30 minutes where costs are high.
4.Proper luminaire placement in the design of new lighting systems and the removal of
unnecessary lamps in existing installations are examples of energy conservation measures.
Luminaires should be positioned to minimize glare and reflection, and work stations should be
oriented and grouped to utilize light most effectively. Daylight should be used when available,
maxi-mum switching control should be provided to the user, and light colours should be used on
walls, ceilings and floors. Tasks should be designed to Present high contrast to the observer.
5.Determination in the illumination level due to dirt accumulation in lighting equipment should
be prevented by adequate maintenance program-mes, cleaning lamps and luminaires, and

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replacement of lamps. As a part of maintenance programs, periodic surveys of installed lighting
with respect to lamp positioning and illumination level should be conducted to take ad-vantage
of energy conservation opportunities as user requirements change. To summarize, a checklist to
reduce loss from lamps and devices would include the following points.
1. Is the highest efficiency lamp being used?
2. Is the highest powered lamp available being used?
3. Is the most efficient luminaire, consistent with good glare control, being used?
4.Have adequate provisions been made for maintaining and cleaning lighting equipment and
lamps.?
ADDITIONAL MATERIAL
PRINCIPLES OF LIGHT CONTROL
When light falls on a surface, depending upon the nature of the surface, some portion the energy
is reflected, some portion is transmitted through the medium of the surface and the rest is
absorbed. It is advantageous to direct the whole of the light output on to surface to be
illuminated, to diffuse the light in order to prevent glare or to change its color. The four general
methods of light control are:
I) Reflection
II) Refraction
III) Diffusion
IV) Absorption
Reflection can be used to change the direction of light through a large angle. Reflection is the
change in direction of a wavefront at an interface between two different media so that the
wavefront returns into the medium from which it originated. The reatio of reflected light energy
to the incident light energy is known as reflection factor. There are two types of reflection:
Specular reflection and Diffuse reflection
Specular reflection: The angle at which the wave is incident on the surface equals the angle at
which it is reflected. Mirrors exhibit specular reflection. For a smooth surface, reflected light
rays travel in the same direction. This is called specular reflection.

Diffuse reflection is when light hits an object and reflects in lots of different directions. This
happens when the surface is rough. Most of the things we see are because light from a source has
reflected off it.
For example, if you look at a bird, light has reflected off that bird and travelled in nearly all
directions. If some of that light enters your eyes, it hits the retina at the back of your eyes. An
electrical signal is passed to your brain, and your brain interprets the signals as an image.
Refraction: When light travels from one transparent medium to another having different density,
the light rays will deviate. Refraction is the change in direction of propagation of a wave due to
a change in its transmission medium. Angle of ray with the vertical in the dense medium is less
than that in the rare medium. When waves travel from a medium with a given refractive index
(the ratio of the velocity of light in a vacuum to its velocity in a specified medium) to a medium
with another at an oblique angle, the phase velocity of the wave changes and so the direction of
the wave changes at the boundary between the media.
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Refraction is described by Snell's law, which states that for a given pair of media and a wave
with a single frequency, the ratio of the sines of the angle of incidence θ1 and angle of refraction
θ2 is equivalent to the ratio of phase velocities (v1 / v2) in the two media, or equivalently, to the
opposite ratio of the indices of refraction (n2 / n1)
= =
s
i
n
𝜃
1 𝑣
1 𝑛
1
s
i
n
𝜃
2 𝑣
2 𝑛
2
Diffusion: When light is reflected from a mirror, the angle of reflection equals the angle of
incidence. When light is reflected from a piece of plain white paper; however, the reflected beam
is scattered or diffused. Because the surface of the paper is not smooth, the reflected light is
broken up into many light beams that are reflected in all directions.
To prevent glare from a light source, a diffusing glass screen can be introduced between the
observer and light source or light may be reflected from a diffusing screen which may be a lamp
bulb enclosed in diffusing glass fitting. In diffused reflection, a ray of light is reflected in all
directions and therefore such surface appears luminous from all possible directions. The
diffusing glass employed is of two types: opal glass and frosted glass.
Absorption : For certain purposes such as color matching in dyeworks and in other industries, an
artificial light is required which approximates very closely to that of daylight . The ordinary
filament lamp has an excess radiation and this problem can be avoided by production of reflector
or screen which will absorb precisely the correct amount of the unwanted wavelengths without
interfering. The absorption may be carried out by using special bluish coloured for the bulb of an
ordinary filament lamp or by using an ordinary bulb in a fitting of special glass.
Neon Lamps
A neon lamp is a sealed glass tube filled with neon gas, which is one of the so-called "noble"
(inert or unreactive) gases on the far right of the Periodic Table. (There are minute quantities of
neon in the air around us: take a deep breath and you'll breathe in a volume of neon as big as an
orange pip!)
There are electrical terminals at either end of a neon tube. At one end, there's a negative terminal
("-ve", shown blue); at the other end there's a positive terminal ("+ve", shown green).
When the tube is switched off, it contains ordinary atoms of neon gas (brown circles).
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Rig the terminals up to a high-voltage power supply (about 15,000 volts—because you need a lot
of "electrical force" to make things happen) and switch on, and you'll literally start pulling the
neon atoms apart. Some of the atoms will lose electrons to become positively charged ions (big
green dots). Being positively charged, these neon ions will tend to move toward the negative
electrical terminal.
The electrons the neon atoms lose (small blue dots) are negatively charged, so they hurtle the
opposite way toward the positive terminal at the other end of the tube.
In all this rushing about, atoms, ions, and electrons are constantly colliding with one another.
Those collisions generate a sudden smash of energy that excites the atoms and ions and makes
them give off photons of red light.
So many collisions happen with such rapidity that you get a constant buzzing of red light from
the tube. You also get quite a lot of energy given off as heat. If you've ever stood near a neon
light, you'll know they can get very hot. That's because the atoms are giving off quite a bit of
invisible infrared radiation (in other words, heat) as well as visible radiation (better known as red
light).
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UNIT-3:
POWER FACTOR AND ENERGY INSTRUMENTS
Power Factor:
Traditionally, power factor has been defined as the ratio of the kilowatts of power divided by the
kilovolt-amperes drawn by a load or system, or the cosine of the electrical angle between the
kilowatts and kilovolt-amperes. However, this definition of power factor is valid only if the
voltages and currents are sinusoidal. When the voltages and/or currents are nonsinusoidal, the
power factor is reduced as a result of voltage and current harmonics in the system. Therefore, the
discussion of power factor will be considered for the two categories, i.e., systems in which the
voltages and currents are substantially sinusoidal and systems in which the voltages and currents
are non-sinusoidal as a result of nonlinear loads.
THE POWER FACTOR IN SINUSOIDAL SYSTEMS:
The line current drawn by induction motors, transformers, and other inductive devices consists of
two components: the magnetizing current and the power-producing current.
The magnetizing current is that current required to produce the magnetic flux in the machine.
This component of current creates a reactive power requirement that is measured in kilovolt-
amperes reactive (kilovars, kvar). The power-producing current is the current that reacts with the
magnetic flux to produce the output torque of the machine and to satisfy the equation
𝑻 =𝑲∅𝑰
Where
T = output torque
Φ = net flux in the air gap as a result of the magnetizing current
I = power-producing current
K = output coefficient for a particular machine
The power-producing current creates the load power requirement measured in kilowatts (kW).
The magnetizing current and magnetic flux are relatively constant at constant voltage. However,
the power-producing current is proportional to the load torque required.
The total line current drawn by an induction motor is the vector sum of the magnetizing current
and the power-producing current.

The vector relationship between the line current IL and the reactive component Ix and load
component Ip currents can be expressed by a vector diagram, as shown in Fig. where the line
current IL is the vector sum of two components. The power factor is then the cosine of the
electrical angle θ between the line current and phase voltage.
This vector relationship can also be expressed in terms of the components of the total kilovolt-
ampere input, as shown in Fig. Again, the power factor is the cosine of the angle θ between the
total kilovolt-ampere and kilowatt inputs to the motor. The kilovolt-ampere input to the motor
consists of two components: load power, i.e., kilowatts, and reactive power, i.e., kilovars.
The system power factor can be determined by a power factor meter reading or by the input
power (kW), line voltage, and line current readings. Thus,
Power factor = kW / kVA
Disadvantages of Low Power Factor:
A low power factor causes poor system efficiency. The total apparent power must be supplied by
the electric utility. With a low power factor, or a high-kilovar component, additional generating
losses occur throughout the system. Figures below illustrate the effect of the power factor on
generator and transformer capacity.
To discourage low-power factor loads, most utilities impose some form of penalty or charge in
their electric power rate structure for a low power factor.
When the power factor is improved by installing power capacitors or synchronous motors,
several savings are made:
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1.A high power factor eliminates the utility penalty charge. This charge may be a separate charge
for a low power factor or an adjustment to the kilowatt demand charge
2. A high power factor reduces the load on transformers and distribution equipment.
3.A high power factor decreases the I2R losses in transformers, distribution cable, and other
equipment, resulting in a direct saving of kilowatt-hour power consumption.
4. A high power factor helps stabilize the system voltage.
Methods of Power Factor Improvement:
The more popular method of improving the power factor on low voltage distribution systems is
to use power capacitors to supply the leading reactive power required. The amount and location
of the corrective capacitance must be determined from a survey of the distribution system and
the source of the low-power factor loads.
In addition, the total initial cost and payback time of the capacitor installation must be
considered.
To reduce the system losses, the power factor correction capacitors should be electrically located
as close to the low-power factor loads as possible. In some cases, the capacitors can be located at
a particular power feeder. In other cases, with large-horsepower motors, the capacitors can be
connected as close to the motor terminals as possible. The power factor capacitors are connected
across the power lines in parallel with the low-power factor load.
The number of kilovars of capacitors required depends on the power factor without correction
and the desired corrected value of the power factor.
The power factor and kilovars without correction can be determined by measuring thepower
factor, line amperes, and line voltage at the point of correction. For a three-phase system,
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The capacitive kilovars required to raise the system to the desired power factor can be calculated
as follows:
Another method of improving powerfactor is connecting a synchronous motor in parallel with
the system and operate it under over excitation condition.
Location of Capacitors:
The power factor correction capacitors should be connected as closely as possible to the low–
power factor load. This is very often determined by the nature and diversity of the load. Figure
illustrates typical points of installation of capacitors:
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At the Motor Terminals:
Connecting the power capacitors to the motor terminals and switching the capacitors with the
motor load is a very effective method for correcting the power factor. The benefits of this type of
installation are the following: No extra switches or protective devices are required, and line
losses are reduced from the point of connection back to the power source. Corrective capacitance
is supplied only when the motor is operating. In addition, the correction capacitors can be sized
based on the motor nameplate information, as previously discussed.
If the capacitors are connected on the motor side of the overloads, it will be necessary to change
the overloads to retain proper overload protection of the motor. A word of caution: With certain
types of electric motor applications, this method of installation can result in damage to the
capacitors or motor or both.
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Never connect the capacitors directly to the motor under any of the following conditions:
 The motor is part of an adjustable-frequency drive system.
 Solid-state starters are used.
 The motor is subject to repetitive switching, or plugging.
 A multispeed motor is used.
 A reversing motor is used.
 There is a possibility that the load may drive the motor (such as a high-inertia load).
In all these cases, self-excitation voltages or peak transient currents can cause damage to the
capacitor and motor. In these types of installations, the capacitors should be switched with a
contactor interlocked with the motor starter.
At the Main Terminal for a Multimotor Machine:
In the case of a machine or system with multiple motors, it is common practice to correct the
entire machine at the entry circuit to the machine. Depending on the loading and duty cycle of
the motors, it may be desirable to switch the capacitors with a contactor interlocked with the
motor starters. In this manner, the capacitors are connected only when the main motors of a
multimotor system are operating.
At the Distribution Center or Branch Feeder:
The location of the capacitors at the distribution center or branch feeder is probably most
practical when there is a diversity of small loads on the circuit that require power factor
correction. However, again, the capacitors should be located as close to the low–power factor
loads as possible in order to achieve the maximum benefit of the installation.
THE POWER FACTOR WITH NONLINEAR LOADS:
The growing use of power semiconductors has increased the complexity of system power factor
and its correction. These power semiconductors are used in equipment such as
Rectifiers (converters)
DC motor drive systems
Adjustable-frequency AC drive systems
Solid-state motor starters
Electric heating

Uninterruptible power supplies
Computer power supplies
In the earlier discussion about the power factor in sinusoidal systems, only two components of
power contributed to the total kilovolt-amperes and the resultant power factor: the active or real
component, expressed in kilowatts, and the reactive component, expressed in kilovars. When
nonlinear loads using power semiconductors are used in the power system, the total power factor
is made up of three components:
1. Active, or real, component, expressed in kilowatts.
2.Displacement component, of the fundamental reactive elements, expressed in kilovars or
kilovolt-amperes.
3.Harmonic component. The result of the harmonics and the distorted sinusoidal current and
voltage waveforms generated when any type of power semiconductor is used in the power
circuit, the harmonic component can be expressed in kilovars or kilovolt-amperes. The effect of
these nonlinear loads on the distribution system depends on (1) the magnitude of the harmonics
generated by these loads, (2) the percent of the total plant load that is generating harmonies, and
(3) the ratio of the short-circuit current available to the nominal fundamental load current.
Generally speaking, the higher the ratio of short-circuit current to nominal fundamental load
current, the higher the acceptable level of harmonic distortion.
Therefore, more precise definitions of power factors are required for systems with nonlinear
loads as follow: Displacement power factor: The ratio of the active power of the fundamental in
kilowatts to the apparent power of the fundamental in kilovolt-amperes.
Total power factor: The ratio of the active power of the fundamental in kilowatts to the total
kilovolt-amperes. Distortion factor, or harmonic factor. The ratio of the root-mean square
(rms) value of all the harmonics to the root-mean square value of the fundamental. This factor
can be calculated for both the voltage and current. Figure illustrates the condition in which the
total power factor is lower than the displacement power factor as a result of the harmonic
currents.
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Unfortunately, conventional var-hour meters do not register the total reactive energy consumed
by nonlinear loads. If the voltage is non sinusoidal, the var-hour meter measures only the
displacement volt-ampere-hours and ignores the distortion volt-ampere-hours.
Therefore, for nonlinear loads, the calculated power factor based on kilowatt-hour and var-hour
meter readings will be higher than the correct total power factor. The amount of the error in the
power factor calculation depends on the magnitude of the total harmonic distortion.
Energy meter (Watt hour meter)
An instrument that is used to measure either quantity of electricity or energy, over a period of
time is known as energy meter or watt-hour meter. In other words, energy is the total power
delivered or consumed over an interval of time t may be expressed as:
𝑡
𝐸𝑛𝑒𝑟𝑔𝑦 =∫ 𝑣(𝑡)𝑖(𝑡)𝑑𝑡
0
If V(t) is expressed in volts, i(t) in amperes and t in seconds, the unit of energy is joule or watt
second. The commercial unit of electrical energy is kilowatt hour (KWh). For measurement of
energy in a.c. circuit, the meter used is based on “electro-magnetic induction” principle. They are
known as induction type instruments. For the meter to read correctly, the speed of the moving
system must be proportional to the power in the circuit in which the meter is connected.
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