6 weeks industrial training report on substation 220 kv BBMB JAMALPUR LUDHIANA hope you all get some help from it

1. BHAKRA BEAS MANAGEMENT BOARD
TRANING REPORT
ON
BBMB
(220 KV SUBSTATION, JAMALPUR, LUDHIANA)
FOR SIX WEEKS
(FROM JUNE TO JULY 2017)
SUBMITTED BY:-
Name:- SAIK SAIFI
CHANDIGARH UNIVERSITY
Gharauan Mohali

2. ABSTRACT
The six weeks training is conducted by the institutions to increase the practical experience of
the student. The student should have to achieve as more as he could from this training. This
training is conducted during the period from June to July 2017 6weeks. I had achieved
the practical experience about the sub-station during this period. The S.S.E. Mr. Harpreet Singh
allowed me to do my training from the 220KV Grid sub-station BBMB, Jamalpur, Ludhiana.
I have done my training at 220kv Grid sub-station BBMB, Jamalpur, Ludhiana. The sub-
station is Installed with power transformers, Bus bars, Insulators, Isolators, circuit breakers,
Capacitor bank, Instrument Transformers (Current Transformer & Potential Transformer)
, Battery bank, transformers, and lightning arrestor etc.
All these instruments are controlled by the panels placed inside the sub-station. The whole staff
of the sub-station is well qualified and experienced. They share their experience with me during
the training.

3. ACKNOWLEDGEMENT
I would like to express my gratitude to all of those who gave me the opportunity to accomplish
my six weeks training. I also like to thank the staff of the 220KV Grid sub-
station, BBMB, Jamalpur, Ludhiana.
Who shares their experience with me and provided me a platform to get the practical knowledge
about my field.
I am sincerely thankful to the other faculty members of Electrical Engineering department of
Chandigarh University for their intellectual support throughout the training.
I would like to thank profusely S.S.E. Er. Harpreet Singh, who allowed me to do six weeks
training at 220KV Grid Substation BBMB, Jamalpur Ludhiana.
I would also like to thank Je. S. Parminder Singh without whose guidance, I was not
able to complete my training. It was impossible to complete the report in this manner without
their wise counsel and able guidance.
I also like to thank the all other staff members of the 220KV Grid substation Jamalpur
SAik Saifi

4. LIST OF TABLES
CHAPTERS
1. INTRODUCTION TO BBMB
2. TRANSFORMERS
3. SUBSTATION
4. RELAY
5. BUS BARS
6. INSULATORS
7. MISCELLANEOUS EQUIPMENTS
8. PROTECTION DEVICES
9. MEASURING INSTRUMENT
10. MAINTENANCE OF SUBSTATION

5. LIST OF FIGURES
Fig.: -Figure
Chapter 1
1.1 Introduction of Substation
Chapter 2
2.1 Transformer
2.2 Working of Transformer
2.3 Core Type Transformer
2.4 Shell Type Transformer
2.5 Power Transformer
2.6 Distribution Transformer
2.7 Auto Transformer
2.8 Current Transformer
2.9 Potential Transformer
Chapter 3
3.1 Fig. Of Substation
Chapter 4
4.1 Differential Relay
4.2 Over Current Relay
4.3 Tripping Relay
Chapter 5
5.1 Bus Bars

6. 5.2 Lightning Arrester
5.3 Isolator
Chapter 6
6.1 Pin Type Insulator
6.2 Suspension Insulator
6.3 Strain Insulator
Chapter 7
7.1 Kit Kat Fuse
7.2 Cartridge Fuse
7.3 H.R.C. Fuse
Chapter 8
8.1 Protection Devices
Chapter 9
9.1 Measuring Instrument

7. KEY DIAGRAM OF SUBSTATION
KEY DIAGRAM

8. CHAPTER 1
INTRODUCTION
INTRODUCTION TO BBMB
SUBSTATION
A Substation is a part of an electrical Generation, Transmission and Distribution system.
Substations are familiar sight alongside highways in cities. Sub-station takes the electricity from
power plants and from transmission line and transform it from high to low and vise-versa and
perform many important functions. The electrical power may flow through several sub-stations at
different voltage levels between the generating station and consumer. A substation may include
power transformers to change voltage levels between high transmission voltages and lower
distribution voltages.
Fig.No. 1.1
The whole procedure is done under the BHAKHRA BEAS MANAGEMENT BOARD PRIVATE LIMITED
(BBMB) Bhakra Beas Management Board Private and limited (BBMB) is the electricity generating company
of the government of Punjab state in India. BBMB was incorporated as company on April 16, 2010
and was given the responsibility of operating and maintenance of state’s own generating project.
The business of generation of power of erstwhile PSEB was transferred to BBMB.
The substation at which I completed my training is 220KV substation Jamalpur. The voltage
is step-down from 220KV to 132KV,66KV,11KV. The sub-station is installed with two power transformers,
Bus bars, Insulators, Isolators, SF6 (SulphurHexaflouride) circuit breakers, VCB (Vacuum circuit breakers),
Capacitor bank, Instrument transformers, Lightning arrestor and Relays and etc.

9. CHAPTER 2
TRANSFORMER
A transformer is a static device which transfers A.C. electrical power from one circuit to other at
the same frequency but the voltage level is usually changed. When the voltage is raised on the
output side, the transformer is called a step-up transformer. Whereas the transformer in which the
voltage level is lowered on the output side is called a step-down transformer.
TRANSFORMER
Fig.No.2.1

10. WORKING OF TRANSFORMER
The basic principle of a transformer is electromagnetic induction.
A simple form of transformer is shown in fig. it essentially consists of two separate winding
placed over the laminated silicon steel core. The winding to which A.C, supply is connected is
called primary winding and the winding to which load is connected is called a secondary winding
WORKING OF TRANSFORMER
Fig.No.2.2

11. CONSTRUCTION OF TRANSFORMER
1. CORE TYPE TRANSFORMER
2. SHELL TYPE TRANSFORMER
1. CORE TYPE TRANSFORMER
CORE TYPE TRANSFORMER
Fig.No. 2.3
In simple core type transformer, the magnetic core is built up of laminations to form a rectangular
frame. The laminations are cut in the form of 'L' and 'l'-shaped strips. In order to avoid high reluctance at
the joints where laminations are butted against each other the alternate layers are stacked
differently to eliminate continuous joint.

12. 2. SHELL TYPE TRANSFORMER
In case of shell type transformer, each lamination is cut in the form of long strip of ‘E’ and ‘I’
Shown in fig. in order to avoid high reluctance at the joints where the laminations are butted
against each other, the alternate layers are stacked differently to eliminate continuous joints.
SHELL TYPE TRANSFORMER
Fig.No.2.4

13. LOSSES IN A TRANSFORMER
1. IRON LOSS
2. COPPER LOSS
TYPES OF TRANSFORMER
1. POWER TRANSFORMER
2. DISTRIBUTION TRANSFORMER
3. INSTRUMENT TRANSFORMER
4. AUTO TRANSFORMER
1. POWER TRANSFORMER
These transformers are used to step up the voltage at the generating stations for transmission purposes and then
to step down the voltage at the receiving stations. These transformers are of large capacity. These transformers
are
usually operated at high average load which would cause continuous capacity copper loss.

14. POWER TRANSFORMER
Fig.No.2.5

15. 2. DISTRIBUTION TRANSFORMER
These transformer is installed at the distribution substations to step down the voltage. These transformers are
Continuously energized causing the iron loss for all the 24 hours, generally the load on these transformer
fluctuate from no load to full load during this period.
DISTRIBUTION TRANSFORMER Fig.No.2.6

16. 3. AUTO TRANSFORMER
An auto transformer with only one winding wound on a laminated core. A part of this winding is common to
both primary and secondary sides. On load, a part of the load is obtained direct from the supply and remaining
part obtained by transformer action. In an ordinary transformer, the primary winding and secondary winding are
electrically insulated from each other but connected magnetically and electrically.
AUTO TRANSFORMER
Fig.No.2.7

17. INSTRUMENT TRANSFORMER
1. CURRENT TRANSFORMER
2. POTENTIAL TRANSFORMER
1. CURRENT TRANSFORMER
The current transformer is basically step up transformer. the connections of an ammeter when used in
Conjunctions transformer for measurement with a current transformer for measurement of current is show fig.
CURRENT TRANSFORMER Fig.No.2.8

18. 2. POTENTIAL TRANSFORMER
The potential transformer is basically step-down transformer. the connections of a voltmeter when used in
Conjunctions with a potential transformer for measurement of high ac voltages are shown in fig. the voltage to
be applied across primary winding which has a large number of turns.
POTENTIAL TRANSFORMER
Fig.No.2.9
The secondary winding which has a much smaller number of turn is coupled magnetically to the primary
Winding. the turn ratio is so adjusted that the secondary voltage is 110 volts when full rated primary voltage is
applied to the primary.

19. CHAPTER 3
SUBSTATION
The present day the electrical power system is A.C. i.e. electrical power generated,
transmitted and distributed in form of alternating current. This alternating current is supplied to
consumers with the help of substations. The figure: 3.1 shows the view of substation
FIGURE OF SUBSTATION
Fig.No.3.1

20. A substation may include transformers to change voltage levels between high transmission
voltages and lower distribution voltages, or at the interconnection of two different transmission
voltages.
The word substation comes from the days before the distribution system became a grid.
As central generation stations became larger, smaller generating plants were converted to
distribution stations, receiving their energy supply from a larger plant instead of using their own
on stations, receiving their energy supply from a larger plant instead of using their own
generators. The first substations were connected to only one power station, where the
generators were housed, and were subsidiaries of that power station.
3.1 TYPES OF SUB-STATION:
3.1.1 According to the service requirement:
3.1.1.1 Transmission Sub-Station
3.1.1.2 Distribution Sub-Station
3.1.1.3 Collector Sub-Station
3.1.1.4 Converting Sub-Station
3.1.1.5 Switch Sub-Station
3.1.2 According to the constructional features:
3.2.1Indoor Sub-Station
3.2.2 Outdoor Sub-Station

21. CIRCUIT DETAILS OF 220KV SUB STATION, JAMALPUR
Incoming Supply
Sr. No. F r o m T o
1 2 2 0 k v g r i d J a l a n d h a r 2 2 0 k v g r i d j a m a l p u r
2 2 2 0 k v g r i d B h a k r a 2 2 0 k v G r i d j a m a l p u r
Outgoing supply
Sr. No. F r o m T o
1 2 2 0 k v g r i d j a m a l p u r 220 kv grid Dhandhari
2 2 2 0 k v g r i d j a m a l p u r 2 2 0 k v S a n g r u r
There are 8 transformers of 100MVA in our grid
132kv outgoing feeders of transformer I, II, III
S r . N o F r o m T o
I 2 2 0 k v g r i d
j a m a l p u r
1 3 2 K V G o r a ya n F e e d e r
I I 2 2 0 k v g r i d j a m a l p u r 1 3 2 K V S f e e d e r
I I I 2 2 0 k v g r i d j a m a l p u r 1 3 2 K V P h i l l o u r F e e d e r
I V 2 2 0 k v g r i d j a m a l p u r 1 3 2 K V M o g a F e e d e r
V 2 2 0 k v g r i d j a m a l p u r 132 K V C i r cui t - I F e ed e r
V I 2 2 0 k v g r i d j a m a l p u r 132 KV Circuit -II Feeder
66kv outgoing feeder of Transformer I, II, III
S r . N o F r o m T o
I 2 2 0 k v g r i d j a m a l p u r 66 KV Chandigarh Road Feeder
I I 2 2 0 k v g r i d j a m a l p u r 6 6 K V N u r e w a l F e e d e r
I I I 2 2 0 k v g r i d j a m a l p u r 6 6 K V S h e r p u r F e e d e r
I V 2 2 0 k v g r i d j a m a l p u r 66 KV Mil l erganj Feede r
V 2 2 0 k v g r i d j a m a l p u r 66 KV Vardhman Steel Feeder
V I 2 2 0 k v g r i d j a m a l p u r 66 KV Vardhman Spinning Feeder
V I I 2 2 0 k v g r i d j a m a l p u r 66 KV Ludhiana Steel Feeder
11kv outgoing feeder of Transformer I, II
S r . N o F r o m T o
I 6 6 k v g r i d j a m a l p u r 1 1 K V I n d u s t r i a l F e e d e r

22. I I 6 6 k v g r i d j a m a l p u r 1 1 K V K a k a F e e d e r
CHAPTER 4
RELAYS
A relay is an electrically operated switch. Many relays use an electromagnet to mechanically
operate a switch, but other operating principles are also used, such as solid-state relays. Relays
are used where it is necessary to control a circuit by a low-power signal (with complete
electrical isolation between control and controlled circuits), or where several circuits must be
controlled by one signal. The first relays were used in long distance telegraph circuits as
amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on
another circuit. Relays were used extensively in telephone exchanges and early computers to
perform logical operations.
Types of Relays
1. Differential relay
2. Over current relay
3. Tripping relay
1. Differential Relay
Differential protection requires a set of current transformers (smaller transformers that
transform currents down to a level which can be measured) at each end of the power line, or
each side of the transformer. The current protection relay then compares the currents and

23. calculates the difference between the two.
Differential Relay
Fig.No.4.1
2. OVER CURRENT RELAY
In an over current relay or o/c relay the actuating quantity is only current. There is only one
current operated element in the relay, no voltage coil etc. are required to construct this
protective relay
Working Principle of Over Current Relay
In an over current relay, there would be essentially a current coil. When normal current flows
through this coil, the magnetic effect generated by the coil is not sufficient to move the moving
element of the relay, as in this condition the restraining force is greater than deflecting force. But

24. when the current through the coil increased, the magnetic effect increases, and after certain level
of current, the deflecting force generated by the magnetic effect of the coil, crosses the
restraining force, as a result, the moving element starts moving to change the contact position in
the relay.
Over Current Relay
Fig.No.4.2
3. TRIPPING RELAY
Trip relay is the main trip relay. The breaker will trip through this relay only in transmission & distribution line
there are so many protection relays like differential, over current, relays etc. All the relays contact will connect
parallel to tripping relay if any of the protection relay sense the fault it will energize the trip relay will trip the
circuit breaker. It got one more mame like lock nut relay.

25. Tripping Relay
Fig.No.4.3
4.Numerical relays:- Numerical relays are based on the use of microprocessors. The first numerical relays
were released in 1985.
A big difference between conventional electromechanical and static relays is how the relays are wired.
Electromechanical and static relays have fixed wiring and the setting is manual. Numeric relays, on the other
hand, are programmable relays where the characteristics and behavior can be programmed. Most numerical
relays are also multifunctional.
Advantages of numerical relays:-
▪ Self-checking facility
▪ Low burden relays improve accuracy
▪ Fast fiber optical communication with substation LAN
▪ Adaptive relaying schemes
▪ Permit storage of historical data
▪ Time stamping

26. CHAPTER 5
BUS BAR
Bus Bars
Fig.No.5.1
1. Lightning arrester
A lightning arrester is a device used on electrical power systems and telecommunications systems to protect the
insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester
has a high-voltage terminal and a ground terminal. When a lightning surdgetravels along the power line to the
arrester, the current from the surge is diverted through the arrestor, in most cases to earth.
If protection fails or is absent, lighting that strikes the electrical system introduces thousands of kilo volts that
may damage the transmission lines, and can also cause severe damage to transformers and other electrical or

27. electronic devices. Lightning-produced extreme voltage spikes in incoming power lines can damage electrical
home appliances.
A lightning arrester may be a spark gap or may have a block of a semiconducting material such as silico carbide
or zinc oxide. It was once a trade name for the silicon carbide used in arresters any spark gaps are open to the
air, but most modern varieties are filled with a precision gas mixture, and have a small amount of radioactive
material to encourage the gas to ionize when the voltage across the gap reaches a specified level.
Lightning Arrester
Fig. No.5.2
Lightning arresters built for power substation use are immense devices, consisting of a porcelain tube several
feet long and several inches in diameter, typically filled with disks of zinc oxide. A safety port on the side of the
device vents the occasional internal explosion without shattering the porcelain cylinder.
Lightning arresters are rated by the peak current they can withstand, the amount of energy they can absorb, and
the breakover voltage that they require to begin conduction. They are applied as part of a lightning protection
system, in combination with air terminals and bonding.
2. Isolator
In electrical engineering, a connect or disconnect switch or isolator switch is used to ensure that an electrical
circuit is completely de energies for service or maintenance. Such switches are often found in electrical
distribution and industrial applications, where machinery must have its source of driving power removed for
adjustment or repair. High-voltage isolation switches are used in electrical substations to allow isolation of
apparatus such as circuit breakers, transformers, and transmission lines, for maintenance. The dis connector is
usually not intended for normal control of the circuit, but only for safety isolation.Dis connector can be operated
either manually or automatically

28. Unlike load break switches and circuit breakers, dis connectors lack a mechanism for suppression of electric
arc, which occurs when conductors carrying high currents are electrically interrupted. Thus, they are off-load
devices, intended to be opened only after current has been interrupted by some other control device. Safety
regulations of the utility must prevent any attempt to open the dis connector while it supplies a circuit.
Standards in some countries for safety may require either local motor isolators or lockable overloads (which can
be padlocked).
Isolator
Fig. No.5.3
Dis connectors have provisions for a padlock so that inadvertent operation is not possible In high-voltage or
complex systems, these padlocks may be part of a Trapped key interlock System to ensure proper sequence of
operation. In some designs, the isolator switch has the additional ability to earth the isolated circuit thereby
providing additional safety. Such an arrangement would apply to circuits which inter-connect power distribution
systems where both ends of the circuit need to be isolated.

29. CHAPTER 6
INSULATORS
INSULATORS
An electrical insulator is a material whose internal electric charges do not flow freely, and therefore
make it impossible to conduct an electric current under the influence of an electric field.
There are mainly three Types of insulators:-
1. Pin Insulator
2. Suspension Insulator
3. Strain Insulator
1. Pin Insulator
A pin insulator consists of a non-conducting material such as porcelain, glass, plastic, polymer,
or wood that is formed into a shape that will isolate a wire from a physical support (or "pin") on
A telegraph, utility pole or other structure, provide a means to hold the insulator to the pin,
and provide a means to secure the conductor to the insulator. By contrast to a strain insulator,
the pin insulator is directly connected to the supporting pole. The earliest pin insulators predate
the strain insulator and were deployed before about 1830. Pin insulators continue in production
with manufacturers worldwide.

30. Pin Type Insulator Fig.No.6.1
2. Suspension Insulator
In higher voltage, beyond 33KV, it becomes uneconomical to use pin insulator because size,
weight of the insulator become more. Handling and replacing bigger size single unit insulator
are quite difficult task. For overcoming these difficulties, suspension insulator was developed.
In suspension insulator numbers of insulators are connected in series to form a string and the
line conductor is carried by the bottom most insulator. Each insulator of a suspension string is
called disc insulator because of their disc like shape.
Suspension Insulator
Fig. No.6.2
3.Strain Insulator
A strain insulator is an electrical insulator that is designed to work in mechanical tension (strain),
to withstand the pull of a suspended electrical wire or cable. They are used in overhead electrical
wiring, to support radio antennas and overhead power lines.

31. When suspension string is used to sustain extraordinary tensile load of conductor it is referred as
string insulator. When there is a dead end or there is a sharp corner in transmission line, the line
has to sustain a great tensile load of conductor or strain. A strain insulator must have
considerable mechanical strength as well as the necessary electrical insulating properties
For low voltage lines, the stays are to be insulated from ground at a height. The insulator used in
the stay wire is called as the stay insulator and is usually of porcelain and is so designed that in
case of breakage of the insulator the guy-wire will not fall to the ground.
STRAIN INSULATOR
Fig.No.6.3

32. CHAPTER 7
MISCELLANEOUS EQUIPMENTS
FUSE
Sometimes in an electric circuit due to short circuit or due to overloads, heavy current flows. If this current will
be more then that of the normal current carrying capacity of the wires used in the circuit ,then this may be result
into serious accident thus is order to protect a circuit from heavy current a protective device is called a fuse.
TYPES OF FUSE:-
1. KITKAT FUSE
2. CARTRIDGE FUSE
3.HRC FUSE
1.KIT KAT FUSE
Rewirable fuse is called kitkat fuse. It can be replaced and is most common type of fuse used for protecting
Device.it has two parts career and base. Base is a fixed part of fuse.carrier carries the fuse wire.
Kit Kat Fuse
Fig.No.7.1

33. 2. CARTRIDGE FUSE
A cartridge fuse is kept enclosed .the fuse kept inside a cylindrical case which is sealed after filling a filler
powder in to .when the current flowing through the circuit increase beyond a certain limit i.e. when the circuit is
overloaded the temperature of fuse wire is increased.
Cartridge Fuse
Fig.No.7.2
3.HRC FUSE
HRC fuse is another type of fuse which is often used a protective device in high voltage equipment .in short it is
Called HRC fuse the fuse wire in this case made of silver and is kept in cylindrical case which is made up of
ceramic.
H.R.C FUSE
Fig.No.7.3

34. CHAPTER 8
PROTECTION DEVICES
Protection devices are used to protect sub-station equipment's like transformers of a sub-station.
PROTECTION DEVICES
Fig. No.8.1

35. CHAPTER 9
MEASURING INSTRUMENT
These devices are used to measure the voltage level, to check air moisture, current level , to check oil level,
ground to ground zone distance of a sub-station etc.
MEASURING INSTRUMENT
Fig.No.9.1

36. CHAPTER 10
MAINTENANCE OF SUBSTATION
1 Maintenance Intervals
Maintenance intervals shall be determined and appropriate maintenance action shall be performed at specified
intervals.
2 Required Inspections
Inspection of transmission lines for defects can be accomplished via ground or aerial patrols. The purpose of
these patrols is to identify transmission line defects which can include: loose / missing / worn hardware,
broken/cracked insulators, broken conductor and static wire strands , guy wires, foundations, loose/missing
structure bolts and other defects.
3 Repair & Maintenance
The defects identified during the transmission line inspection shall be repaired based upon the priority and
significance of the defect. Routine maintenance activities such as structure painting, grounding system testing,
right-of-way maintenance, etc. shall be performed on a routine basis
TRANSFORMERS
.1 Long replacement lead times, high first cost and the need for high reliability dictate that power transformers
be maintained in accordance with Good Utility Practice. This includes attention to industry standards and to
manufacturer’s recommendations. Maintenance includes inspections, testing and corrective tasks. While there
are manufacturer recommended and typical utility
maintenance frequencies for these tasks, the frequency for activities, such as oil testing and visual inspections,
may need to be increased in response to specific situations, such as an indication of a deteriorating condition
that cannot be immediately addressed.
2 The following are typical maintenance activities. Note that some activities, such as temperature and oil level
monitoring, require very frequent or even continuous attention. This is generally accomplished through
SCADA system alarm monitoring.
BREAKERS
1 The following are typical preventive inspection and maintenance activities applicable to general purpose
modern SF-6 Gas circuit breakers.
Monitoring overall condition of circuit breakers including but not limiting to checking gas pressure and
corresponding temperature, operating mechanism air/hydraulic pressures , operation counters, visual inspection
of porcelain and control cabinet.

37. Periodic preventive maintenance in accordance with Good Utility Practice and/or manufacturers instructions.
Typical preventive maintenance should include but not be limited to performing infrared inspections, SF-6 gas
moisture test as required, check monitoring systems for proper operation, timing test, ductor test, Double test or
equivalent.
Overhauls should be performed based on equipment condition,diagnostic testing and operating duties. Circuit
breakers used under severe operating conditions such as capacitor bank switching or a process requiring breaker
operation on a routine basis will require more stringent periodic maintenance.
LOAD INTERRUPTING SWITCHES
1 Disconnect switches should be periodically maintained in accordance with Good Utility Practice, the
manufacturer’s instructions and with applicable industry standards. Periodic preventive maintenance should
include but not be limited to infrared inspection, check and adjust for proper alignment, clean, lubricate and
perform ductor tests.
FAIR DISCONNECT SWITCHES
1 Disconnect switches should be periodically maintained in accordance with Good Utility Practice, the
manufacturer’s instructions and with applicable industry standards. Periodic preventive maintenance should
include but not be limited to infrared inspection, check and adjust for proper alignment, clean, lubricate and
perform ductor tests.
INSTRUMENT TRANSFORMERS
1 Instrument transformers should be maintained in accordance with manufacturer's recommendations. This
may include visual inspections (paint, porcelain, oil leaks), insulation power factor, and ratio tests.
AC STATION SERVICE
1 AC station service system components, including engine- generators, must be periodically maintained by
qualified personnel in accordance with applicable industry standards and practices to assure proper operating
capability and reliable service.
2 To assure reliable operating performance diesel engine-generator maintenance must include routine exercise
of the unit to its operating temperature, which require s placing adequate load on the unit.
BATTERY AND CHARGER SYSTEMS
1 Batteries shall be maintained at a periodicity and in such a way as to ensure a duty cycle of at least 8 hours.
2 Battery monitoring systems are an alternative to conducting manual inspections. These systems can provide
automatic notification of required maintenance.

38. SUBSTATION/SWITCHYARD MAINTENANCE
1 Maintenance of the substation site shall include upkeep of any barriers, walls, buildings, fences, animal
proofing and minimization of extraneous vegetation.
2 Special attention must be paid to maintenance of relay and control buildings. Roof leaks, breaches in
security etc., can have immediate effects on system reliability.
CARRIER CURRENT LINE TRAPS
1 Line traps should be maintained in accordance with manufacturer’s recommendations. This may include
infrared scans, Inspection of the mechanical integrity of the main coil, and checks of carrier blocking
performance.
Surge Arresters
1 Routine maintenance primarily consists of condition assessment checks. Moisture sealing systems are a
common weak point.Periodic Power factor tests can be helpful in finding surge arresters on the road to
catastrophic failure. On line leakage current measurement may be able to detect impending arrester block
failure. In polluted environments, cleaning of the insulating housing may be required to maintain TOV
performance.

39. CHAPTER 11
SAFETY
In substations while working on any equipment first supply is disconnected by circuit breaker and then section
isolate by isolators within the guidance of a skilled or higher authority person.
For double sure a temporary earth switch is attached to the equipment for security measures