some general guidelines for electcal work execution at site

1. GUIDELINES
FOR
ELECTRICAL WORK
1

2. STANDARDS
The Electrical installation work shall confirm to the following I.S. Standards
(latest additions), Local Supply Authorities Rules and Regulations, Indian
Electricity Act & rules, National Building code and Fire Safety Norms. All
equipment including cables, wires & components thereof should be
manufactured & installed as per standards specified by Bureau of Indian
Standards (BIS) Where such standards do not exist, then the covered items
should be approved from Architects / Consultants /Purchasers prior to purchase
& delivery to site .
1) IS: 732 Code of Practice for Electrical wiring installation
(System Voltage not exceeding 650V)
2) IS: 1646 Code of Practice for fire safety of buildings - (General Electrical
Installation).
3) IS: 3043 Earthing.
4) Indian Electricity Act, 1956 and Rules and Fire Insurance Regulations.
5) IS:2274 Electrical wiring installations (System voltage exceeding 650 volt)
6) IS :7752 Guide for improvement of power factor consumer’s installations
7) IS :5216 Guide for safety procedures & practices in electrical work
8)
IS:3072 Installation & maintenance of Switch gear
9)
IS:2551 Guide for danger notice plates
10) IS :8923 warning symbols for dangerous voltages
11) IS :13947 Specification for low-voltage switchgear & Control gear
12) IS :1777 Industrial luminaries with metal reflectors
13) IS :1913 General & safety requirement of luminaries
14) IS :116 Circuit Breakers for AC system
15) IS :3427 Metal enclosed switchgear & Control gear
16) IS: 3837 Accessories for rigid steel conduits.
17) IS: 4047 Heavy duty Air break switches & composite switch fuse units for
voltage exceeding 100 volts.
18) IS :4237 General requirements for switchgears not exceeding 1000 Volts
19) IS:159: Bus bars & bus bars connections
20) IS: 415 marking & arrangement for switchgear board’s main connections &
auxiliary wiring.
21) IS :415 Tungsten filament lamp
22) IS : 722 Three phase watt hour meter with MDI
23) IS :1248 Directing acting electrical indicating instruments
24) IS :2147 Degree of protection provided for enclosure for switchgear
25) IS : 2075 Current Transformer
26) IS : 2834 LT Capacitors
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3. 27) IS: 3106 Code of practice for installation & maintenance of switchgear.
28) IS : 2607 Air break isolators for voltage not exceeding 1000 Volts
29) IS : 1753 aluminum Conductors for insulated conductor
30) IS : 3961 Recommended current ratings for cables
31) IS : 3480 Flexible steel conduits for electrical wiring
32) IS : 1646 Code of fire safety of building (General Electrical installation)
33) IS: 6381 Specifications for construction & testing of electrical apparatus.
34) IS :1818 Isolator & Earthing switches
35) IS : 3106 Code of practice for selection
36) IS : HRC Cartridge fuse unit up to 650 Volts
3

4. CABLES (UPTO 1.1 KV)
1.0
General: :
This section covers the activities connected with unloading, inspection, handling, storage,
installation and termination of power, control and instrumentation cables up to and including
1.1 KV grade.
This does not apply for installation of cable for special applications such as, mines, quarries
and oil fields.
1.1
Reference Standards :
1. IS – 1225 – 1983 and latest standard -- Code of Practice for Installation and
Maintenance of Power Cables Up to And Including 1.1 KV Rating.
2. Indian Electricity Rules – 1956.
3. Indian Electricity Act – 1910 and as amended.
2.0
Activities connected with installation of cable are categorized as below:1.
Inspection on receipt, unloading and storage.
2.
Handling and installation.
3.
Termination and jointing.
4.
Testing and commissioning.
5.
Handing over.
Detailed instructions for above activities are given in the subsequent paragraphs.
3.0
Inspection on receipt, unloading and storage :
Verification of the consignment received should be carried out to confirm the compliance to
the Delivery challan and Purchase order with respect to length, size and type of the cables
received as marked on the cable drums.
3.1
The cable drums or coils must not be dropped or thrown from railway wagons or trucks during
unloading operations. A ramp or crane may be used for unloading cable drums. If neither of
these is available, a temporary ramp with inclination 1:3 to 1:4 approximately should be
constructed. The cable drums should be rolled over the ramp by means of ropes and
winches. Additionally a sand bed at the foot of the ramp may make to breaks the rolling of the
cable drums.
3.2
The arrows painted on the flange of the drums indicate the direction in which the drum should
be rolled. The cable will unwind and become loose if the drum is rolled in the opposite
direction.
3.3
The site chosen for storage of cable drums should be well drained and should preferably have
a concrete surface/firm surface which will not cause the drums to sink and thus lead to flange
rot and extreme difficulty in moving the drums.
3.4
All drums should be stored in such a manner as to leave sufficient space between them for air
circulation. It is desirable for the drums to stand on battens placed directly under the flanges.
During storage, the drums should be rolled to an angle of 90 deg. Once every three months.
3.5
In no case should the drums be stored ‘on the flat’ that is, with flange horizontal.
3.6
Overhead covering is not essential unless the storage is for a very long period. The cable
should, however, be protected from direct rays of the sun by leaving the battens on or by
providing some form of sun shielding.
3.7
When for any reason, it is necessary to rewind a cable on to another drum; the barrel of the
drum should have a diameter not less than that of the original drum.
3.7.1 The drums should be inspected after unloading for any damage to the planks, flanges, and end
seals.
3.7.2 In case any plank is damaged or dislodged during transit the cable rolls at that place and its
vicinity should be checked for any damage.
3.7.3 The planks should be replaced, if no damage to the cable roll is noticed.
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5. 3.7.4 In case of any damage to the cable rolls which may be detrimental to the performance of the
cable the matter should be reported to the concerned agencies and open delivery should be
taken from the transporter.
3.8
Handling and Installation :
3.8.1. Preliminary:
a. Thorough study of the cable lay-out drawing should be carried out before taking up the
laying.
b. Length of various feeders has to be ascertained by taking up measurement in conjunction
with the route as indicated in the lay-out drawing.
c.
Cable cutting schedule should be prepared based on the measurement and various drum
lengths available to minimize the wastage and, preferably, this should be got approved by
the Purchaser/Consultant. Appropriate extra length for looping at the ends, if laid outdoor,
should be allowed.
3.8.2 Secondary :a. Cable drum should be transported by using a suitable fork lift, trolley etc., if available.
Alternatively, drum may be rolled by rolling in the direction of arrow marked on the drum.
b. Cable route should be checked for any obstacles and, if so, the same should be got
cleared.
c. Care should be taken to ensure that the route is free from stones, projection etc.which
may damage the cable, if the planks are removed.
d. Inspection has to be carried out to check for any external damage after un planking.
e. Cable should be maggered after opening seals at both ends and separating cores to
provide minimum clearance. It should be megger using certified megger of 1000 V for LV
cables and the same should be recorded before laying. The cable should be resealed
after Meggering.
3.8.3 Minimum permissible bending radi :
When bending is encountered while laying the cable, the following minimum bending radi
should be maintained.
Single core
Multicore
a. Up to 1.1 KV Grade
15 D
(‘D’ represents Diameter of cable).
12 D
3.8.4 Conventional methods of cable laying and installations are :a.
b.
c.
d.
e.
Laying directly in ground
Drawing in ducts.
Laying on trays/racks in air.
Laying on trays/racks inside cable trenches.
Laying along building or structure.
3.8.5 Laying direct in ground :
a. Depth :- The desired minimum depth of laying from ground surface to the top of the cable
is as follows :
Low voltage & control cables
0.75 “
Cables at road crossings
1.00 “
Cables at Railway level crossings
1.00 “
( measured from bottom of sleepers to the top of pipe)
Before digging the trench the possibility of the existing cables, pipe lines etc. to avoid
damage to the same while digging should be ascertained.
b. Minimum 75 mm bedding of riddled earths or sand as specified at the bottom of the cable
and additional 75 mm on the top of the cable should be provided. Suitable protective
covering of bricks or slabs as specified after laying the cable should be provided.
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6. c.
Clearances :
The desired minimum clearances are as follows:i.
Power cable to Power cable
- Clearances not necessary.
However, follow the specifications
Of the Purchaser.
- 0.2 M
ii.
iii
Power cable to Control cable
Power cable to communication
cable.
- 0.3 M
iv. Power cable to gas/water main - 0.3 M
3.8.5.1
3.8.5.2
Cables laid across roads :
a. Steel, cast iron, plastics, cement or earthenware ducts or cable ducting blocks should be
used where cables across roads and railway tracks. Spare ducts for future extensions
should be provided. Spare duct runs should be sealed off. Buried ducts or ducting blocks
should project into footpath or up to the edge of road, where there is no foot path to permit
smooth entry of cable without undue bending.
b. The duct/pipe joints should be covered by collars to prevent settlement of in between
pipes. It may be desirable to leave a pilot wire inside the ducts.
c. The diameter of the cable conduit or pipe or duct should be at least 1.5 times the outer
diameter of cable. The ducts/pipes should be mechanically strong to withstand forces due
to heavy traffic when they are laid across road/railway tracks.
d. Pipes should be buried at least 1 Mtr. below the road level.
e. Spare pipes also may be provided if desired.
f. Spare pipes should be sealed at ends.
g. After drawing the cable seal the end of the pipe suitably using bitumen, cement etc.
h. The cable should always be pulled off the top of the drum. In doing so, the drum should
be placed in such a way that the painted arrow points to the opposite direction of the
pulling. The drum is jacked up with a drum axle to such a height that the plank needed for
braking cannot jam; heavy drums should be jacked up with hydraulic drum pedestals.
i. Suitable provisions should be made to brake the drum in order that during a sudden stop
further rolling and consequent buckling of the cable is avoided. The kinks (nooses) after
particularly dangerous and should be avoided at all costs. A simple plank can serve as
drum brake. When pulling, the cable drum is turned by hand in order to avoid excessive
tensional stress, which may damage the cables, particularly smaller un armored cables.
j. The leading end of the cable is untied from the cable drum and a cable stocking placed
over it and secured firmly. A rope is attached to the cable stocking pulling eye. No pull
should be exerted on the end of the cable.
k. Identification strips/tags of metal or plastics should be attached to the cables, particularly if
several are laid in parallel, 8 to 10 M apart. Identification tags should also be attached at
every entry point the buildings and at the cable and termination.
Laying on Racks in air:
a. Inside buildings, industrial plants, generating stations, sub-stations and tunnels, cables are
generally installed on racks fixed to the walls or supported from ceiling. Racks may be
ladder or perforated type and may be either fabricated at the site or pre-fabricated.
Considerable economy can be achieved using standard factory made racks. The
necessary size of the racks and associated structure has to be worked out taking into
consideration the cable grouping and permissible bending radii.
b. The space provided for cable racks has to be sufficient. They are generally fixed to the
wall or supported by free standing columns or structures enabling easy installation or
replacement of cables.
c. The vertical distance between the two racks should be minimum 0.3 m and the clearance
between the first cable and the wall (if racks are mounted on wall) should be 25mm. The
width of the rack should not exceed 0.75 m in order to facilitate installation of cables.
d. The cables are laid directly on the trays with or without spacers. Each tray should
preferably contain only one layer of cables. Stacking cables one above other in 2 or 3
layers on one rack or tray reduces their current carrying capacity to a very great extent.
More than one tier trays are permissible if the cables present cannot be accommodated in
a single tray.
e. Ungalvanised steel work of cable racking/trays should be painted with a coat of primer and
thereafter finished with suitable anti-corrosive paint.
f. Only single core cables laid on horizontal racks need be clamped at suitable intervals.
Multi-core cables need not be clamped.
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7. g. The distance between the vertical clamps should not be more than 2m.
h. Identification strips/tags metal or plastics should be attached to the cables, particularly if
several are laid in parallel, 8 to 10 m apart. Identification tags should also be attached at
every entry point into the buildings and at the cable end termination.
4.0 Testing:
After the cable is laid megger the cable as done before laying and record the results. Jointing
and termination of cable:
Before starting termination megger the cable and ensure that the cable is healthy:
1. If cable terminations are these days generally carried out using single compression/
double compression brass glands and soldieries aluminum or tinned copper lugs
2. Cables of size up to 16 sq.mm may be crimped by mechanical and crimping tools,
mechanical manual tools, if recommended by the manufacturer may be used up to 185
sq.mm cable.
3. For cables of size above 185 sq.mm. use only hydraulic tools.
4. Ensure that the die used is of proper size. small type having self adjustable die may be
used upto size 185 sq.mm or higher size, if suitable tool is available.
5. Ensure that the hydraulic type tool is in proper working condition and builds full pressure
required to make perfect crimp.
6. While stripping the cable for glanding ensure that the separated core will have proper
length for dressing inside the panel so that the end portion need not be cut and wasted.
7. While glanding follow proper method and ensure that the armouring (for armored cable)
is firmly secured by the gland.
8. Ensure the lug is of proper size and type.
9. Clean the stripped core and apply crimping flux before inserting the lug.
10. Gland and armored should be effectively earthed at both ends.
Precautions:
1. Take proper precautions to avoid accidental in injury to the Personnel from excavated
trench.
2. Provide necessary guarding and danger board if the excavation is in public place.
3. Provide red light indicator during night time if the excavation is in public place.
4. Remove any big stone or other material from the edge of the trench so that the laid
cables are not damaged due to their falling on them.
5. While laying inside a running factory or premises ensure that the cable is safeguarded for
any falling welding muck, heavy objects etc.
6. Never pull the cable in such a way that the cable is twisted or develops kinks.
7. While laying on trays and racks ensure that there are no sharp edges etc. on the tray
which may damage the outer sheath of the cable.
5.0
LIGHTING:General:
This section covers the following category of lighting installation:
· Office premises.
· Data Centre area.
· Utility services for Data Centre.
Type of wiring:
Wiring is generally done in the looping system of wiring without any jointing. Phase wires shall
be looped in switch control points and neutral shall be looped at outlet points.
Point wiring:
Point wiring includes all materials and works necessary to complete wiring of a switch circuit of
any length from the tapping point on the distribution board to the following via the switch.
a.
b.
c.
d.
Ceiling rose and connector (in the case of ceiling/exhaust fan points).
Back plate (in case of fluorescent fitting with down rods etc.).
Socket outlet with switch (in the case of socket outlet point).
Lamp holder (in case of wall brackets, bulk-head and similar fittings).
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8. The following shall be needed to be included in the point wiring:
a. Switch
b. Ceiling rose or connector as required.
c. Any special or suitable round block for neatly housing the connector and covering the fan
hook in case of fan point.
d. Wooden box, bushed conduit, porcelain tubing where cable passes through wall etc.
e. Conduit or metallic covering upto 1.5 M from floor.
f. Earth wire from three pin socket outlet point/fan regulator to common earth including earth
dolly except the earth wire from the first tapping point of live wire to the sub-distribution
board.
g. All wood or metal blocks, boards and boxes sunk to surface type including those required
for mounting fan regulator but excluding those under the main and distribution switchgear.
h. All fixing accessories such as clips, rails, screws, phil plugs, rawl plugs, wooden plugs etc.
as required.
i. Connections to ceiling rose, connector socket outlet, lamp holder, switch and fan regulator
etc.
j. Looping the same switchboard and inter-connections between points on the same circuit.
k. Providing fish wire in conduits while recessed conducting work is undertaken.
Circuit wiring:
Circuit wiring shall mean the length of wiring from the Distribution board upto the 1st nearest
tapping point of that circuit, measured along the run of the conduit for the maximum number of
points or load or a circuit.
Sub mains:
Sub mains wiring shall mean the length of wiring from the main/distribution switchgear to
another main/distribution switchgear measured along the run of wiring.
Load on a circuit:
Lights, 5 A sockets and exhaust fans may be wired on a common circuit. Such circuit shall
have 10 points of light, exhaust fan and socket outlets or a load of 800 Watts, whichever is
less. It shall, however, be ensured that in one switchboard wiring of one circuit is only
provided.
Size of Conductor:
The smallest copper conductor to be used for lighting circuits shall be 1.5 sq.mm and for
power circuits 2.5 sq.mm. Wiring shall be done in the ‘looping system’. Phase or live
conductors shall be looped at the switch box and neutral conductor can be looped from the
light, exhaust fan or socket outlet, neutral conductor and earth continuity wire shall be brought
to each switchboard situated in rooms and halls, these shall be terminated inside the
switchboards with suitable connectors and the switchboard shall be of adequate size to
accommodate one number 5 A socket outlet and control switch in future.
Conduit capacity:
Maximum number of PVC insulated cable conforming to IS: 694-1977 that can be drawn in
one conduit shall be as follows:-
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9. Nominal
Cross sectional
Area of
Conductor
in sq. mm.
1.50
2.50
4
6
10
16
25
35
50
70
6.0
Size of conduit
19 mm
S B
25mm
S B
5
5
3
2
2
-
10
8
6
5
4
2
-
4
3
2
-
8
6
5
4
3
2
-
32mm
S B
38mm
S B
18 12
12 10
10 8
8 7
6 5
3 3
3 2
-
8 6
6 5
5 3
3 2
- - -
52mm
S B
10
8
6
5
4
7
6
5
3
3
64mm
S B
12
9
5
8
7
6
5
4
EARTHING
General:
This Section covers the preparation of earth electrode by digging pit in the soil and also for
earth mat in switchyard.
1.1
Reference Standards :
IS-3043 – 1966 – Code of practice for Earthing:
Earthing shall generally be carried out in accordance with the provision of above Standard and
the requirements of Indian Electricity Rules, 1956 as amended from time to time and the
relevant regulations of the Electricity supply Authority concerned. The following Indian
Electricity Rules are particularly applicable: - 32, 51, 61, 62, 67, 69, 88 (2) & 90.
1.2 General Requirements :
All medium voltage equipment shall be earthed by two separate and district connection with
earth through an earth electrode. In the case of high and extra high voltages the neutral
points shall be earthed by not less than two separate and district connections with earth each
having its own electrode at the generating station or substation and may be earthed at any
other point provided no interference is caused by such earthing. If necessary, the neutral
may be earthed through suitable impedance.
As far as possible all earth connections shall be visible for inspection.
1.3
All connections shall be carefully made; if they are poorly made or inadequate
the purpose for which they are intended, loss of life or serious personal injury may
result.
1.4
Each earth system shall be so devised that the testing of individual earth electrode
is possible. It is recommended that the value of any earth system resistance shall
not be more than 5 Ohms unless otherwise specified.
1.5 It is recommended that a drawing showing the main earth connection and earth
electrodes be prepared for each installation.
1.6 All fittings etc. used in earthing shall conform to Indian Standard specifications
wherever these exist. In the case of materials for which Indian standard
9

10. specifications do not exist. The material shall be approved by the competent
authority.
Preparation of Earth Electrode:
1.7
Where there is any option, a site should be chosen in one o the following types of
soil in order of preference.
a. Wet marshy ground and grounds containing refuse such as, ashes, cinders and brine
waste.
b. Clayey soil or loam mixed with small quantities of sand
c. Clay and loam mixed with varying proportions of sand, gravel and stone
d. Damp and wet sand pit.
1.8
Electrodes should preferably be situated in a soil which has a fine texture and
which is packed by watering and ramming as tightly as possible. Where
practicable the soil should be sifted and all lumps should be broken up and stones
removed in the Immediate vicinity of the electrodes.
1.9
Recourse may be had to chemical treatment of soil to improve the conductivity.
Common salt is generally used for this purpose and the addition of less than one
part by weight of salt to 200 soil moisture has been found to reduce the resistivity
by 80 percent but there is little advantage in increasing the salt content above 3
percent. Calcium chloride, sodium carbonate and other substances too have been
found beneficial. But before chemical treatment is applied, it should be verified
that no deleterious effect on the electrode material will result.
1.10
Use should be made, where possible, of natural salts in soils produced by
bacteriological action on decaying plants. The resistivity of soil on which plants
are growing will be lower than that of the same soil in the absence of plants.
1.11
In places where the soil conditions appear to be extensively corrosive, the soil
may be chemically examined before deciding the material of the earth electrode.
1.12
Earth Electrode material:
1.12.1 Although electrode material does not affect initial earth resistance, care should be taken to
select a material which is resistant to corrosion in the type of soil in which it will be used.
1.12.2 Under ordinary conditions of soil, use of copper, iron or mild steel electrodes is
recommended. However for all neutral earthing copper plate earthing or maintenance free
chemical earthing is recommended and for general equipment body earthing it is suggested to have
either GI plate earthing or maintenance free chemical earthing.
1.12.3 In cases where soil conditions points to excessive corrosion of the electrode and the
connections, it is recommended to use either copper electrode or copper clad electrode or
zinc coated (galvanized) iron electrodes.
1.12.4 In direct current system, however due to electrolytic action which causes serious
corrosion, it is recommended to use only copper electrodes.
1.12.5 The electrode shall be kept free from paint, enamel and grease.
It is recommended to use similar material for earth electrodes and earth
conductors or otherwise precautions should be taken to avoid corrosion.
1.13
Types of Earth Electrodes:
1.13.1 Rod and Pipe Electrodes :
1.13.2 These electrodes shall be made of metal rod or pipe having a clean surface not covered by
paint; enamel or poorly conducting material.
1.13.3 Rod electrodes of steel or galvanized iron shall be at least 16mm in diameter and those of
copper shall be at least 12.5mm in diameter.
10

11. 1.13.4 Pipe electrodes shall not be smaller than 38 mm internal diameter if made of galvanized iron
or steel and 100 mm internal diameter, if made of cast iron.
1.13.5 Electrodes shall, as far as possible, be embedded below permanent moisture level.
1.13.6 The length of rod and pipe electrodes shall not be less than 2.5 M.
1.13.7 Except where rock is encountered, pipes and rods shall be driven to a depth of at least 2.5 M.
Where rock is encountered at a depth of less than 2.5 M, the electrodes may be buried
inclined to the vertical. In this case the length of the electrodes shall be at least 2.5 M and
inclination not more than 30 deg. From the vertical.
1.13.8 Deeply driven pipes and rods are, however, effective where the soil resistivity decrease with
depth or where substratum of low resistivity occurs at depth greater than those to which rods
and pipes are normally driven.
1.13.9 Pipes or rods, as far as possible, shall be one piece.
1.13.10 For deeply driven rods, joints between sections shall be made by means of screwed
coupling which should not be or greater diameter than that of the rods which it connects
together.
1.13.11 To reduce the depth of burial of an electrode without increasing the resistance, a number of
rods or pipes shall be connected together in parallel. The resistance in this case is practically
proportional to the reciprocal of the number of electrodes used so long as each is situated
outside the resistance of the other. The distance between two electrodes in such a case
shall preferably be not less than twice the length of the electrode.
1.13.12 If necessary, rod electrodes shall have a galvanized iron water pipe buried in the ground
adjacent and parallel to the electrode itself. Its one end shall be at least 5 cm above the
surface of the ground and need not be more than 10 cm. The difference between the
lengths of the electrode and that of the pipe if under the earth’s surface shall not be more
than 30 cm and in no case shall the length of the pipe exceed that of the electrode.
1.14
Strip or Conductor Electrodes :
1.14.1 Strip electrodes shall not be smaller than 25 mm x 1.60 mm if of copper and 25 mm x 4 mm if
of galvanized iron or steel. If round conductors are used as earth electrodes, their crosssectional area shall not be smaller than 3.0 mm sq. if of copper and 6 mmsq. if of galvanized
iron or steel.
1.14.2 The length of buried conductor shall be sufficient to give the required earth resistance. It
shall, however, be not less than 15 M.
1.14.3 These shall be buried in trenches or ditches not less than 0.5 M deep.
1.14.4 The electrodes shall be as widely distributed as possible, preferably in a single straight or
circular trench or in a number of trenches radiating from a point.
1.14.5 If the conditions necessitate use of more than one strip, they shall be laid either in parallel
trenches or in radial trenches.
1.15
Plate Electrodes:
1.15.1 Plate electrodes when made of galvanized iron or steel shall be not less than 6.30 mm in
thickness. Plate electrodes of copper shall be not less than 3.15 mm in thickness.
1.15.2 Plate electrodes shall be of size at least 60 cm.
1.15.3 Plate electrodes shall be buried such that its top edge is at a depth not less than 1.5 M from
the surface of the ground.
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12. 1.15.4 Where the resistance of one plate electrode is higher than the required value, two or more
plates shall be used in parallel. In such a case two plates shall be separated from each other
by not less than 3.0 M.
1.15.5 Plates shall preferably be set vertically.
1.15.6 Use of plate electrode is recommended only where the current carrying capacity is the prime
consideration, for example, in generating stations and substations.
1.15.7 If necessary, plate electrodes shall have a galvanized iron water pipe buried vertically and
adjacent to the electrode. One end of the pipe shall be at least 5 cm above the surface of
the ground and need not be more than 10 cm. The internal diameter of the pipe shall be at
least 5 cm and need not more than 10 cm. The length of pipe if under the earth’s surface
shall be such that it should be able to reach the center of the plate. In no case, however,
shall it be more than the depth of the bottom edge of the plate.
1.16
Earthing Continuity Conductors:
1.16.1 The minimum allowable size of earth wire is determined principally by mechanical
consideration for they are more liable to mechanical injury and should therefore be strong
enough to resist any strain that is likely to be put upon them.
1.16.2 All earth wires and earth continuity conductors shall be of copper, galvanized iron or steel or
aluminum.
1.16.3 They shall be either stranded or solid bars or flat rectangular strips and may be
provided due care is taken to avoid corrosion and mechanical damage to it.
bare
1.16.4 Interconnections of earth-continuity conductors and main and branch earth wires shall be
made in such a way that reliable and good electrical connections are permanently ensured.
Note: Welded, bolted and clamped joints are permissible.
For stranded
conductors, sleeve connectors (for example, indented, riveted or bolted
connectors) are permissible. Bolted connectors and their screws shall be protected
against any possible corrosion.
1.16.5 The path of the earth wire shall, as far as possible, be out of reach of any person.
1.16.6 If the metal sheath and armor have been used as an earth electrode, the armor shall be
bonded to the metal sheath and the connection between the earth wire and earthing
electrode shall be made to the metal sheath.
1.16.7 If a clamp has been used to provide connection between the earth wire and the metal sheath
and armor, it shall be designed and installed as to provide reliable connection without
damage to the cable.
1.16.8 The neutral conductor shall not be used as earth wire.
1.16.9 Connection to earth of those parts of an installation which require to be earthed shall be
made by means of an earth-continuity conductor which may be a separate earth conductor,
the metal sheath of the cables, or the earth – continuity conductor contained in a cable,
flexible cable or flexible cord. Water pipes shall not, under any circumstances, be used as
earth continuity conductors.
1.16.10 Earth continuity conductors and earth wires not contained in the cables – The size of the
earth-continuity conductors should be co-related with the size of the current carrying
conductors, that is the sizes of earth continuity conductors should not be less than half of the
largest current carrying conductors, provided the minimum size of earth-continuity conductors
is not less than 1.5 sq. mm for copper and 2.5 sq. mm for aluminum and need not be greater
than 70 sq. mm for copper and 120 sq. mm for aluminum. As regards the sizes of galvanized
iron and steel earth-continuity conductors, they may be equal to the size of the current
carrying capacity conductors with which they are used. The size of earth-continuity
12

13. conductors to be used along with aluminum current carrying conductors should be calculated
on the basis of equivalent size of the copper current carrying conductors.
1.17
Earth Wires :
1.17.1 Earth wires shall be protected against mechanical damage and possibility of corrosion
particularly at the point of connection to earth electrode or earth continuity conductor. The
connection of the earth wire to the earth electrode or earth continuity conductor shall be
readily accessible and soundly made by the use of soldered joints or substantial clamps of
non-ferrous material.
1.18
Earthing at Substations, Generating Stations :
1.18.1
The earthing system shall be mechanically robust and joints shall be capable of retaining
low resistance even after many passages of fault current.
1.18.2
Joints shall be riveted, bolted, brazed or welded. Where the diameter of the bolt exceeds
one quarter of the width of the earth bar, the connection to the bolt shall be made with a wider
piece or flag of copper jointed to the earth bar. The design of joints shall be based on a
maximum allowable temperature rise, which in the case of bolted joints should be limited to
250 deg. C and for brazed joints to 450 deg. C.
1.18.3 Main earth bars shall be spaced sufficiently from the surface on which they are fixed
such as, wall or trenches to allow for the connections to be made easily. Where a
portable apparatus is to be earthed, a suitable loop attached to the earth bar shall be
provided to accept the earthing clamp.
1.19
Measurement of Earth Electrode resistance :
1.19.1 A certified earth megger should be used for measuring the resistance of the earth electrode.
1.19.2 Fall of Potential Method :
In this method two auxiliary earth electrodes, besides the test electrode, are placed
at suitable distances from the test electrode. A measured current is passed between
the electrode ‘A’ to be tested and an auxiliary current electrode ‘C’ and the potential
distance between the electrode ‘A’ and the auxiliary potential ‘B’ is measured.
1.19.3 At the time of test, where possible, the test electrode shall be separated from the earthing
system.
1.19.4 The auxiliary electrodes usually consist of 12.5 mm diameter mild steel rod given upto 1 M
into the ground.
1.19.5 All the test electrodes and the current electrodes shall be so placed that they are independent
of the resistance area of each other. If the test electrode is
in the form of rod, pipe or
plate, the auxiliary current electrode ‘C’ shall be placed at least 30 M away from it and the
auxiliary potential electrode ‘B’ shall be placed mid-way between them.
1.19.6
Unless three consecutive readings of test electrode resistance with different spacing of
electrodes agree the test shall be repeated by increasing the
distance
between
electrodes ‘A’ and ‘C’ upto 50 M and each time placing the electrode ‘B’ mid-way between
them.
1.20
Alternative Method:
1.20.1 If above method described does not give satisfactory results if the test electrode is of very low
importance (One Ohm or less). This applies particularly, while measuring the combined
resistance of large installations. In these cases, the following method may be adopted.
13

14. 1.20.2 Two suitable directions, at least 90 deg. apart, are first selected. The potential lead is laid in
one direction and an electrode is placed 250 to 300 Mts. from the fence. The current lead is
taken in the other direction and the current electrode located at the same distance as the
potential electrode. A reading is taken under this condition. The current electrode is then
moved out in 30 M steps until the same reading is obtained for three consecutive locations.
The current electrode is then left in the last foregoing position and the potential electrode is
moved out in 30 M steps until three consecutive readings are obtained without a change in
value. The last readings then correspond to the true value of earth resistance.
7.0 LT PANELS/LT CABLES/DBs/SWITCH GEAR
A.1
DISTRIBUTION BOARDS:
This specification covers the design, manufacture, assembly, testing at works, supply,
installation and commissioning of distribution boards at site.
The system and accessories shall be complete in all respects and any device not
included specifically in this specification, but essential for proper operation of the
equipment and also to meet statutory requirements shall deemed to be within the
scope of the specification whether it is mentioned in the Technical Specification or
not.
If the vendor finds that it is required to undertake any work which is not sufficiently
defined in this specification, or discovers that this specification conflicts with any
other codes, standards and regulations which shall be required to comply, the same
shall be clarified in writing from the Owner/Consultant before undertaking work
involved for avoiding the delay.
A.1.1 CONSTRUCTION
The distribution boards shall be fabricated out of 14 SWG sheet steel metal , totally
enclosed dust damp and vermin proof IP52,dead front, hinged door type of
bolted/welded construction suitable for wall or floor mounting.
The board frames shall be fabricated using suitable mild steel structural sections or
pressed & shaped cold rolled sheet steel of thickness not less than 2.0mm.The frames
shall be enclosed by cold rolled sheet steel of thickness not less than 2.0mm ,smoothly
finished ,leveled & free from flaws. Doors & covers shall be made of cold rolled sheet
steel of thickness not less than 2.00 mm .Stiffeners shall be provided wherever
necessary.
A.1.2 BUSBARS
The bus bar shall be air insulated and made up of high conductivity high strength
copper bus bars liberally sized with high safety factor for the required rating. The
current density shall not exceed 130amp per sq.cm for Aluminum &160 amp per sq.cm
for copper neutral bus shall be rated for 100% capacity of phase bus unless otherwise
stated in schedule of quantities/drawings. However, the minimum size of bars shall be
25mm x 3mm. The neutral bus bars shall have adequate number of terminals for all
number of outgoing single phase circuits and the holes shall be suitable for multistoried
wires. In the same way suitable earth bus shall be provided inside each distribution
board for earthing of the lighting/power circuits and also earthing of distribution
board. In case of 3 phase DB used for single phase outgoing, three independent
neutral bars shall be provided.
A.1.3 MINIATURE CIRCUIT BREAKERS
·
·
Miniature circuit breakers (MCB) shall be of heat resistant, molded type
designed, manufactured and tested as per IS-8828.
The MCBs shall have inverse tripping characteristic against overloads and
instantaneous trip against short circuits.
The MCB shall be of fault current
limiting device also.
14

15. ·
·
·
·
·
The MCB shall be clip on type to the DIN rail. The ON & OFF positions of the
switch handle shall be clearly marked. The MCB shall be suitable for operating
in an ambient temperature of 45 deg C. without derating. The MCB shall be
suitable for 415V, 3 phase, and 50 Hz system with a fault level of 9-10 KA
(RMS) symmetrical. The terminals of MCBs shall be suitable for use with eye
lugs. The 4 pole, 3 pole and 2 poles MCBs knobs shall be trunked with
adequate strength tandem pin.
Each distribution board shall have individual hinged/bolted gasketed doors
with suitable screws. Removable conduit entry plates shall be provided at
top and bottom of the DB to facilitate drilling the conduit holes at site to suit
individual requirements or knock out shall be provided.
Protective insulated cover plate shall be provided inside the panel to shroud all
the live parts. Only the operating handle of the switch and the operating knob
of the miniature circuit breakers shall be projecting outside the cover plate in
case of ordinary DB and shall be inside the front door in case of dust tight DB.
The unused outgoing gap of DB shall be suitably blanked with PVC plates at
no extra cost. The incoming switch terminal should be suitably shrouded to
avoid accidental contact. Each outgoing in the MCB DB shall have shrouding
between Phases. The distribution board shall be factory wired and assembled
and local fabricated DB shall not be accepted.
If the Distribution Board shall be triple pole and neutral, four pole isolator shall be
provided as incomer and for single phase and neutral Distribution Board, double
pole isolator shall be provided. Earth leakage circuit breaker to be provided
wherever called for.
Suitable label shall be provided to mark the circuit number of outgoings circuits.
A.1.4 EARTHING
The DBs shall be provided with two numbers brass earthing terminals with
suitable nuts, washers, etc., for connecting to earth bus outside the DB. In case
of flush mounting DB, these shall be provided inside the DB.
A.1.5
PAINTING
The DB sheet steel surface shall be pre treated through seven tank process
chemically cleaned to remove scale etc., rinsed dried and shall be finished
with powder coated paint over two coats of red oxide primer.
A.1.6 INSTALLATION
The board shall be fixed at accessible heights. The boards shall be solidly fixed to
walls/partitions, concealed or open as directed. All connections inside the distribution
board shall be neatly arranged and tied with PVC strings. The distribution boards shall
be suitably earthed. Legend shall be written on D.B. with paint for identification of D.B. &
Circuits.
A.2 SWITCH FUSE UNITS:
Switch Fuse Units shall be of sheet metal or iron clad with HRC fuses as described in
schedule of quantities. SFUs complies to IS:4047 .The unit shall be of robust
construction of standard specified make, design to withstand adverse working
conditions. It shall have quick break type mechanism with ON and OFF position
indicators of the operating handle. The switch shall be interlocked so that the unit
cannot be opened in ON condition. The interior shall be so arranged that clearance from
live parts are adequate and shrouded. Manufacturer’s instructions shall be followed
for installation of switch fuse units. The switch shall be solidly earthed. The switch
shall be mounted on walls on angle iron support grouted to wall. The supports shall be
treated for rust treatment & painted with 2 coats of synthetic enamel paint. The height of
the switch board shall be such that it is accessible for operation & maintenance.
A.3 POWER PANELS:
15

16. ·
The Power panels shall be fabricated from MS sheet steel 14/16 gauge and shall
be of compartmental design. The main supporting framework shall be of angle
iron or of heavier gauge sheet metal. The panel shall be self-supporting design,
dust and vermin proof, dead front and fully inter locked with isolating switches.
The panel-mounted switches shall have Interlock defeat for testing and
inspection.
·
The board frames shall be fabricated using suitable mild steel structural sections
or pressed & shaped cold rolled sheet steel of thickness not less than
2.0mm.The frames shall be enclosed by cold rolled sheet steel of thickness not
less than 1.65 mm, smoothly finished, leveled & free from flaws. Doors & covers
shall be made of cold rolled sheet steel of thickness not less than 1.65 mm.
Stiffeners shall be provided wherever necessary.
The panel shall be powder coated comprising of seven tank pre treatment
,degreasing and de-scaling in sulphuric acid etc & shall be finished with powder
coated paint over two coats of red oxide primer. powder coating synthetic enamel
paint for smooth finish. The color of paint shall be battle-ship grey or as directed.
The panel shall be designed so as to facilitate inspection, cleaning and repairs.
The clearance between phase to phase and phase to earth or metal parts shall
be as per relevant IS standards. The metering instruments like volt meter,
ammeter etc. shall be flush mounted and shall be of 1.0 class accuracy and of
standard design size shall be 96 mm x 96. All indication lamps shall be of LED
type.
The bus bars shall be air insulated and made up of high conductivity,
electrolytic aluminum complying with the requirement of IS 5082:1981 and
shall have a fault withstand capacity of 50 KA/1 Sec. The current density shall
not exceed 0.8 amp per sq.m &1.25 amp per sq.m for copper & aluminum
respectively All bus bars shall be fully screened by means of PVC sleeves in their
own compartment running throughout the length of the Panel. Suitable
allowance should be made for bus expansion.
The panel shall have separate cable ally and a bus bar chamber. The bus
bars shall be rigid hard drawn tinned electrolytic copper wherever specified &
sleeved with heat shrinkable sleeves. The current density shall not exceed 1.25
amp per sq.m and the neutral bus shall be rated for capacity of phase bus
unless otherwise stated in schedule of quantities/drawings. However, the
minimum size of bars shall be 25mmx3mm. Minimum electrical clearance shall
be maintained between phases, neutral and body as per IS 4237:1982.All
Incoming / outgoing feeders shall have neutral link of appropriate capacity in the
compartment of switching device .
·
·
·
·
·
Wiring inside the switchgear shall be carried out with 1100 V grade ,single core
PVC insulated, stranded copper conductor wires.
o Minimum size of conductor for power circuit is 4.0 sq.m.
o Minimum size of conductor for control circuit is 1.5 sq.m .
o The size for CT circuit wiring should be of 2.5 sq.m.
·
The Panel shall be tested at site before commissioning. The Panel drawings
shall be got first approved from Consultants before taking up for fabrication.
All wiring inside the panel shall be done with switchboard copper
conductors/cables solid copper links. The insulators for supporting the Bus-Bars
shall be epoxy based cast resin. All hinged doors shall be earthed with
flexible braided copper earth. An earth bus of copper shall be fixed along the
length of the panel at the lower section. Adequate ventilation for the panel
shall be provided. Logic diagram of operation of switches shall be painted on the
panel. The name plates for each feeders shall be of engraved design and
pasted to the respective switch gear. The letters shall not be less than 10 mm
size for individual feeders and not less than 18 mm for the main feeders. All
switchgear to be mounted in the panel shall be as per schedule of quantities.
·
A.4.1 General Constructional Features
Switchgear shall be
a) On door, floor mounting, modular type ( wall mounted wherever specified
,instructed)
16

17. b) Provided with protection of IP52
c) Vermin proof construction
d) Provided with metal sill frame of structural steel channel section properly drilled
for mounting the switchgear along with necessary mounting hardware.
e) Provided with gaskets all round the perimeter of removable covers & door
f) No equipment needing manual operation shall be located less than 250 mm
above ground level.
A.4.2 MCCBs
·
·
·
·
·
·
·
·
·
·
·
MCCB shall in general conform to IS: 13947 part-2,All MCCB shall be of
continuous duty.
MCCB shall be flush mounted on the AC/DC distribution boards.
250 Amps MCCBs shall be provided with thermo-magnetic type release for over
current and short circuit protection. The setting of the thermal release shall be
adjustable between 75% to 100% of the rated current. The magnetic release
setting shall be adjustable between 300% to 600% of the thermal release setting
at site.
MCCBs higher than 250 Amps rating should have microprocessor based
releases having Short circuit, Overload & earth fault protection.
MCCBs shall also have 2 NO and 2NC auxiliary contact either built-in or using
auxiliary switch for purchaser’s use.
MCCB to have trip contact for have remote trip indication
MCCBs shall be manually operated. The operating handle should give a clear trip
indication
Miniature circuit breaker (MCB) shall conform to IEC: 898-1987 and IS: 8828.
The MCCBs shall comprise single units of triple pole construction & shall be
rated for 500 V AC.
All live parts shall be totally enclosed in a heat resistant molded insulating
material housing.
Operating mechanism shall be quick make, quick break & trip free type.
A.4.3 INSTRUMENT TRANSFORMERS
·
·
·
·
·
·
All CTs will be dry type. All current transformers shall be completely
encapsulated cast resin insulated type suitable for continuous operation at the
temperature prevailing inside the switchgear enclosure, when the switchboard is
operating at its rated condition and the outside ambient temperature is 50C.
All instrument transformers shall be able to withstand the thermal and
mechanical stresses resulting from the maximum short circuit and momentary
current ratings of the associated switchgear.
All instrument transformers shall have clear indelible polarity markings. All
secondary terminals shall be wired to a separate terminal on an accessible
terminal block where star-point formation and earthing shall be done.
All CTs utilized in metering circuit will be of class 1.0 & burden of 10 VA minimum
wherever not specified.
All CTs utilized in protection circuit will be of class 5P10 & burden of 10 VA
minimum wherever not specified.
All CTs shall be earthed through a separate earth link.
A.5
WIRING:
a)
METAL CONDUITS:
·
·
All conduit pipes shall confirm to IS 9537 PART-II 1981 . Metal conduits shall
be ERW black enameled of wall thickness of 1.6 mm, 20mm/25mm as the case
may
be depending upon the number of wires permitted as table-1. The
conduits shall be fixed to walls/ceiling with M.S. saddles and spacers at an
interval of 1 meter and on either side of bends.
All conduit accessories shall be 16 gauge & bends shall be of inspection type.
All bends, couplers, threaded portions etc. shall be painted with anti-corrosive
paint. Bends in the pipes shall be done with bending hackles.
17

18. ·
·
·
·
·
b)
All pipes shall be cleaned for sharp burrs. Switch boxes shall be of G.I.
16G/14G. The switch boxes shall be concealed as per site requirement & as per
Architect’s/Consultant’s Instructions.
Point shall be controlled with 6A switch or directly from DB as specified in
schedule of quantities. Where plate type switches are not specified the switch
board shall have 3mm thick hylum sheet on which switches shall be mounted.
The wiring shall be carried out with multi stranded PVC insulated copper
wires of 1.5 sq. mm. 2nos Phase & Neutral) & 2.5sqmm(Earth) . In all cases the
earth shall be of green color and neutral shall be black color. All wires used
shall be of 1100V grade. The point wiring shall be inclusive of circuit wiring
from Distribution Board to the switch board unless otherwise stated in schedule
of quantities. The circuit wiring shall be with 3 nos. of 2.5 sq. mm PVC
insulated multi stranded copper conductors color coded as detailed above.
The rate shall also be inclusive of any chasing as directed by the
Architects/Consultant/Client's Engineer to conceal the drops and finishing
the same.
In case of group control directly from Distribution Board, the primary point
shall be from D.B. to the first point and secondary point from first point to the
next point looped. The point shall terminate into three way junction box.( In
case of wiring in PVC conduit the 3 plate-ceiling rose to be utilized)
While laying the conduits in the slab before casting the slab, all drops shall be
laid accurately to fall in position of the switchboard. Junction boxes shall be sand
filled. All joints shall be airtight. Conduits shall be fastened to the re-enforcement
properly so that the conduits do not get dislocated while casting the slab. All
conduits shall have 18 swg fish wire.
PVC CONDUITS:
·
·
The PVC Conduits shall confirm to latest IS :2509 and shall be of wall thickness
of 2mm. The conduits shall be joined with PVC adhesive at Joints. The Conduits
shall be fixed to walls/ceilings with GI, Spacers and Saddles at an interval of
60 cms & on either side of bends. The number of wires drawn in the conduits
shall be as per table 1. The point wiring shall be controlled as in (a) above.
The wiring shall be done with 2nos. of 1.5 sq. mm (Phase & Neutral).&
2.5sqmm (earth) PVC Insulated, copper conductors, multi stranded and color
coded with green as earth and black neutral.
The circuit wiring shall be with 3 nos. of 2.5 sq. mm PVC insulated, copper
conductors, multi stranded from distribution board to switch board and the rate
shall be included in the point wiring unless otherwise stated in the schedule of
quantities . All other details shall be as for metal conduits.
TABLE :1
Size of Wires (Made to Is 694)
Capacity of conduit
1.5 sq.m
20mm dia
7
25mm dia
15
2.5 sq.m
5
11
4.0 sq.m
4
8
6.0 sq.m
3
6
10.0 sq.m
2
4
A-6.0.
ELECTRICAL FIXTURES
·
·
·
All lighting fittings shall be complete with accessories & fixtures necessary for
installation whether so detailed under item description or not.
Fixture housing, frame or canopy shall provide a suitable cover for the fixture
outlet box or fixture opening.
Fixtures shall be completely wired & constructed to comply with the regulations &
standards for electrical lighting fixtures ,unless otherwise specified. Fixtures shall
bear manufacturer’s name & factory inspection label unless otherwise approved.
18

19. ·
·
·
Wiring within the fixtures & for connection to the branch circuit wiring shall be not
less than 1,5sqmm copper for 250 volt application. Wire insulation shall suit the
temperature conditions inside.
Metal used in lighting fixtures shall be not less than 22 SWG. Or heavier if so
required to comply with specification of standards. Non reflective surfaces & trim
shall be finished in a baked enamel paint.
Fixtures with visible frames shall have concealed hinges & catches. Recessed
fixtures shall be constructed as to fit into an Armstrong /Gypsum/POP false
ceiling.
A-7.0 INSTALLATION OF ELECTRIC FITTINGS:
·
·
·
·
·
Fixtures shall be installed at mounting heights as detailed on the drawings or as
instructed on site by the Architect/Consultants.
Fixtures or fixtures outlets boxes shall be provided with hangers to adequately
support the complete weight of the fixture. Design of hangers & methods of
fastening shall be submitted to the Architects for approval prior to execution at
site.
All fluorescent lighting fixtures shall be fixed with down rods or on round blocks
as stated in schedule of quantities. The down rods shall be 20 mm dia and
1.6mm wall thickness of ERW black enameled MS. The down rods shall be
fixed with ball and socket joints check nuts etc.
Lighting fixtures shall be mounted on round block in case of wall mounting.
Fixtures like down lighter ,spot lights etc. shall be fixed to the false ceilings as
per manufacturer's recommendations.
A-8.0 POWER FACTOR CORRECTION PANEL:
·
The power factor correction panel shall be fabricated from sheet steel & powder
coated. The panel shall be compartmentalized with tinned copper bus bars TPN
as described for power panels. The capacitor housing should be well ventilated.
·
The power capacitors shall be APP type, low loss, 3 phase, delta connected &
self discharged type.
The power factor control shall be done by intelligent microprocessor based
automatic power factor control relay of minimum 16 stages for controlling the
power factor within the set limits by auto switching of required capacitor Banks.
The required Capacity /P.F Banks shall be as per schedule of quantities. The
P.F. shall be automatically corrected to near Unity.
The C.T. ratio given in the Schedule/diagram is indicative. The same shall be
matched for correct operation depending upon the operating load. The relay
shall be totally microprocessor based for setting the desired target power factor
band. The APFC relay shall have indications like power ON, low current etc &
shall be of required stages as per schedule of quantities. The P.F Panel shall
have Auto Manual switching facility.
·
·
The general specification shall be as follows:
·
·
·
·
·
·
·
·
·
·
Systems supply voltage 415 volts.
C.T. secondary rating 5 A, 5 VA Burden.
Output switching capacity 5A at 230 V AC & 2A at 440 V AC, Operating
temperature, 10 degree Centigrade to 50 degree Centigrade. Accuracy better
than 1%.
Low current release 10% of full rated C.T.
Switching time between stages 4 to 6 seconds.
Range of indications of PF 0.5 lag to 0.5 lead digital.
Display LCD indications.
Range of target P.F. setting 0.7 to Unity.
Switch for auto/manual operation.
Indications for selection of stages.
19

20. ·
A-9.0
·
·
·
·
·
·
·
·
·
·
·
Selection of dead band.
TESTING & COMISSIONING
The scope of work for testing and commissioning of the total installation shall
be for the capital equipments like switchgears, cables etc., and also for the
associated equipments like relays CTs, PTs, etc.
The scope of work for testing and commissioning of electrical equipment for
the above shall include but not be limited to the following:
Providing sufficient number of experienced Engineers, Supervisors, Electricians
so that the installation can be commissioned in stipulated time.
All the instruments, tools and tackles required for carrying out the testing and
commissioning shall be provided by the bidder.
The testing of electrical equipment shall be carried out as per the relevant
Indian Standards/Code or Practices/Manufacturer's instructions.
Cleaning of electrical equipment, contacts cleaning and greasing etc. All the
equipment and material required for above shall be supplied by the bidder.
Correcting the panel/equipment wiring for proper functioning of the schemes
required/called for.
Installation and wiring of additional equipment on panels like auxiliary
contactors, timers, etc. which may be additionally required for proper functioning
of the schemes.
Checking of equipment earthing and system earthing as a whole.
Testing of all the cables.
Co-ordination with other contractors for testing and commissioning of interface
cables.
MECHANICAL CHECKOUT
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
After installation, but before any power supply is connected, the contractor
shall make a complete mechanical check of all installed electrical equipment
and systems. This shall include but not to be restricted to the following:
Check equipment numbers against drawings/documents.
Check name plates of switchgears, etc., for conformity with the data given in
the drawings and specifications.
Check all equipment bus joints and connections for tightness.
Check all cable and wire connections for tightness.
Check phase sequence.
Check all bushings/insulators to ensure they are clean and unchipped. Inspect
tank cooling tubes and radiators for leaks.
Check silica gel for dryness where breathers are supplied. If the color of the
silica gel is pink, remove from the breather and dry out following
manufacturer's recommended procedure, until a light blue color is restored and
replace it.
Check interlocking on access doors for mechanical and electrical safety.
Check that key and electrical interlocking system functional and accomplish
their purpose.
Check all plug in contacts for alignment and 'grip'.
Check all contactors for free manual operation.
Remove all locking devices installed for shipment.
Check all the coils for their continuity and proper voltages.
Check the arc chutes, arcing horns, main contacts of breakers are clean
and undamaged. Check the carriages ride smoothly and reliably on their
guide
rails. Check for proper operation of circuit breaker
operation mechanism, controls and adjustments.
Check the fuses are correctly rated and installed are clear, undamaged and fit
for operation.
Check all relays and instruments are clean, correctly connected and
undamaged. Check test plugs are installed in all protective relays. Check
relays for free manual operation, if applicable.
Check instrument transformer ratings against drawings. Check for proper
installation and connection.
20

21. ·
·
Check interlock and auxiliary devices and the operation of the circuit
breaker with the protection relay circuit.
Clean the equipment by vacuum cleaner before energizing.
EARTHING:
·
·
·
Bidder shall test the buried earth grid and shall record the values.
Bidder shall inspect and test all earthing work carried out by him, including
all interconnections between ground loops, grounding of equipment and
ensure all connections are permanent and that the earthing circuit is
continuous.
Bidder shall megger and record earth resistance at various earth connection
points.
SWITCHGEAR:
·
·
·
·
·
·
Switchgears rated 433 volts or more shall be tested with a 1000 volts megger.
Auxiliary wiring rated less than 415 volts shall be tested with a 500 volts megger.
All protective relays shall be tested at sufficient points to establish their
proper functioning in accordance with the manufacturer's specification and
curves.
Operation checks and functional checks on all switchgear panels.
For current transformers insulation test, polarity test, ratio test, secondary
injection test, operating current check, service setting in consultation with
Client/Consultant.
Contact resistance for breaker contacts between male and female.
WIRES AND CABLES:
·
·
·
·
Continuity testing of all cables.
Wires and cables rated 433 volts or more shall be tested with a 1000 volts
megger. Cables rated less than 433 volts shall be tested with a 500 volts
megger.
Wires or cable having Insulation resistance between conductors or between
conductors and ground of less than 10 mega ohm shall not be accepted.
All cable length & circuits to be tested for earth loop impedance test after
termination & charging.
POWER POINTS:
· All power points are to be tested for earth loop impedance test.
FUNCTIONAL TESTING:
· All circuit breakers, contactors, relays, remote devices, etc., shall be checked
for its operations.
UPS & FLOOR MOUNTED PDU: TECHNICAL SPECIFICATION
8.0
UPS SPECIFICATIONS
8.1
GENERAL
This section covers technical specifications for double conversion modular online
UPS banks synchronize together to give power to the rated load in N+N
configuration. Technical parameters of the systems are enclosed in annexure &
bidder shall fill data sheets in the format enclosed as annexure to this
specifications. Annexure duly filled in shall be enclosed along with the tender.
UPS shall be selected on 100% of IT rated load in main server area and disaster
recovery area. UPS shall also be provided for main server IT load,
communication racks and row cooling fans. No diversity shall be considered
either in main server block or Disaster recovery area.
21

22. Tenders not complying with this requirement shall not be considered. Each
bidder shall submit detailed layouts of UPS, battery banks along with the bid.
Bidder shall submit floor layouts, floor loads for battery & UPS along with offer.
The bidder need to supply two no’s of modular UPS in parallel redundant mode
making N+N configuration. These modular UPS shall be of 10-30KW each
assembled in one frame size to give required output as per the design.
8.2
DOCUMENT TO BE SUBMITTED WITH BID
List of following documents and information shall be submitted by
Bidders:a)
b)
c)
d)
e)
f)
g)
h)
8.3
UPS along with entire dimension and layout plan as per site.
Completely filled technical data sheets to be submitted with
supporting international catalogues.
Model no. of the UPS shall be clearly mentioned.
The battery sizes, the battery weights, banks sizing along with the
battery layout.
BMS connectivity shall be boldly displayed.
Remote monitoring facility and hardware provided for remote
monitoring.
Service supporting engineers available in Delhi.
Service Escalation matrix.
STANDARDS
a) Safety:
· Europe : EN/EC62040-1-1, EN/IEC 62040-2,
· USA/ Canada: UL1778 – Standards for Uninterruptible Power Supply Equipment.
b) UL Listed
c) CE-Marked
d) Vender qualifications:
ISO 9001/14001 Certification: The manufacturer shall be ISO 9001/14001
certified.
Copy of certificates needs to be attached with the bid.
8.4
ENVIRONMENTAL CONDITION
The UPS shall be able to withstand the following environmental
without damage or degradation of operating characteristics:
conditions
a) Operating ambient temperature
UPS: 0ºC to 40ºC
Battery: 25 ± 1ºC
b) Altitude Operating:
To 1000 meters above mean Sea Level de-rated for higher altitude
applications. 1% per 100m between 1000 & 2000
c) Audible Noise
Noise generated by the UPS under any condition or normal operation
shall not exceed 65 db A measured 1.0 meter from surface of the
UPS.
8.5
SYSTEM DESCRIPTION:
Each UPS units in the proposed solution shall be self redundant and
scalable architecture. Each unit shall comprise of hot swappable and
user replaceable UPS and battery modules along with user replaceable
continuous duty bypass static switch module in it. Each ups shall have at
least two redundant controller modules to control the compete functions
of the ups system.
22

23. Each ups shall be supplied with redundant logic power supplies, and a
LCD interface display at the front door of the ups. Notification should
be provided on the UPS integrated display for add or removal of UPS
modules & battery modules.
Power & battery modules shall be able to add / swap seamlessly without
engaging the bypass system. System static switch shall be capable of
being fed from the same input to the rectifier or a separate input. Active
Power Factor Correction shall be built in to the UPS.
Each units shall be supplied with complete accessories for synchronizing
each other to make the solution N+N redundant for the rated load.
Mode of operation: The UPS shall operate as an on-line system in the
modes listed below:
8.5.1
Normal: The inverter/ battery charger shall operate in an on-line manner to
continuously regulate the power to the critical load. The Inverter/ battery charger
also shall derive power from the AC Input source and supply D.C Power to floatcharge the battery.
8.5.2
Battery: Upon failure of the AC Input source, the critical load shall continue
being supplied by the Inverter without switching. The Inverter shall obtain its
power from the battery. There shall be no interruption in power to the critical load
upon failure or restoration of the AC Input source.
8.5.3
Recharge: Upon restoration of the AC input source, the Inverter/ battery charger
shall simultaneously recharge the battery and regulate the power to the critical
load.
8.5.4
Bypass: The static bypass switch shall be used for transferring the critical load
to mains supply without interruption. Automatic re-transfer to normal operation
shall also be accomplished with no interruption in power to the critical load.
8.5.5
Basic Functions :
· Battery Management Function - The UPS has advanced battery
management functions including battery modules fault detection and
backup time forecast.
· Soft Start Function - Complete delay soft start function can reduce the
surge to the UPS unit and utility source.
· Alarm and Protection Function - The UPS can generate audible and
visual alarm through LCD, N/O, N/C contacts and network transmission.
It can help maintenance personnel to locate and clear the faults that are
sent out in time, accurately and in detail.
· Automatic Re-start when Utility returns – Upon failure of the input
mains supply the UPS shall goes to battery mode. After the batteries are
completely discharged the UPS system shall shut down. Upon
resumption of power the units must automatically restart & starts
supplying power to the load without any manual intervention
Future Expansion: Each UPS shall be scalable & field upgradeable to enhance
the capacity by adding the UPS modules.
8.5.6
Batteries
·
·
·
·
The battery and the rack will also be modular just like UPS.
The system shall be capable of providing full load with 10 minutes of
battery back-up time for each UPS
DC ripple: Max. 1%.DC bus voltage.
Battery Recharge: In addition to supplying power for the inverter load,
the rectifier/charger shall be capable of producing battery-charging
current to recharge the battery. After the battery is recharged the
rectifier/charger shall maintain the battery at full charge until the next
emergency operation.
23

24. ·
·
·
·
·
·
·
·
·
8.6
Both float and recharge voltages shall be adjustable. The charge voltage
can also be manually controlled.
Low Battery Voltage Protection: To prevent total discharge or damage to
the battery, the UPS shall transfer to standby operation when the battery
voltage reaches a set minimum voltage level (programmable). If The AC
source has not resumed within 5 mins after “low battery shutdown” the
UPS shall electronically disconnect DC Power from the battery to avoid
deep discharge.
Battery Monitor: A battery function shall be capable of monitoring and
defining battery capacity. It shall be possible to program the unit to
perform an automatic battery test every 30 days to test the condition of
the battery.
Battery Management:
The UPS must have advanced battery management functions
Faulty Battery module detection
Backup time forecast.
Batteries shall be hot swappable & user replaceable in nature.
Notification should be provided on the display for add or removal of UPS
battery modules.
SYSTEM PARAMETERS:
8.6.1
Input Voltage rating : [380] [400] [415] volts three-phase, four-wire plus
ground.
8.6.2
Input Voltage range: +10%, -10%
8.6.3
Input Frequency: 50Hz +/-5%
8.6.4
Input Current Distortion: 6% THD maximum from 25% load to 100%
load and nominal input voltage without additional harmonic filters.
8.6.5
Output Frequency: 50Hz +/- 0.1 Hz free running (battery operation).
Mains synchronized normal operation.
8.6.6
Output Power Factor Range: 0.8 leading to 0.8 lagging at rated KVA.
Preferably the UPS shall deliver full rated power at unity load power
factor.
8.6.7
Crest Factor: 3 : 1 or better.
8.6.8
Overload Capability:
a) 150% for 30 seconds
b) 105% continuous
Bypass operation:
a) 125% continuous
b) 1000% for 500 milliseconds
8.6.9
AC to AC efficiency: > 95% from 25% load to 100% non linear load, at nominal
input voltage with batteries fully charged and efficiency shall be clearly
mentioned at 40%, 50%, 80% and 100% load with supportive literature. This
efficiency should be inclusive of any filters installed in the system.
8.7
FIELD AND AFTER SALES SERVICE
8.7.1
The UPS manufacturer shall have a service organization available
consisting of factory trained field service personnel to perform start-up,
preventative maintenance, and service of the UPS system and power
equipment. The service organization shall offer 24 hours a day, 7 days a
week, 365 day a year service support along with toll free number to log
complaints.
8.7.2
Parts shall be available though the service organization 24 hours a day,
24

25. 7 days a week, 365 days a year within the same city of installation.
8.7.3
Product quoted should have minimum 8-10 similar and higher sizes installations
in India.
8.7.4
A complete offering of preventative and full service maintenance contacts for the
UPS system and the battery system shall be available. Contract work shall be
performed by factor trained service personnel. Manufacturing company should
have minimum 1 manufacturing plants in India
8.7.5
IIT Delhi technical committee, at their discretion may visit the site with same
capacity at a short notice.
8.7.6
UPS Service Training workshop: A UPS Service training workshop shall be
conducted at the customer site by the UPS manufacturer. The service training
workshop shall include a combination of lecture and practical instructions. The
service training workshop shall include instruction about safety procedures, UPS
operational theory, subassembly theory, subassembly identification and
operation, system controls and adjustment, preventive maintenance, and trouble
shooting.
8.8
WARRANTY
The UPS manufacturer shall warrant the UPS & batteries against defects in
workmanship and material, for 1 year from the date of successful handing over
of the system. ,. The warranty shall include coverage of all internal parts,
including modular batteries & its frame.
8.9
EXTERNAL ISOLATION TRANSFORMER WITH SEPARATE BUILT IN
INTELLIGENT TYPE PDU HAVING BRANCH LEVEL REMOTE MONITORING
Separate K13 duty factory fitted floor mounted external isolation transformer shall
be provided with low inrush current and surge suppressor at output. . Power from
external isolation transformer shall be fed to floor mounted intelligent PDU
having branch level remote monitoring,IP based. This will be installed in N+N
configuration and shall cater to complete IT load. PDU shall be rated to support
full rated IT load in main server and disaster recovery area. For disaster recovery
area this can be inbuilt in UPS. All outgoing feeders will have branch power
parameters monitoring inside PDU along with remote monitoring also. These
PDU’s will be floor mounted. After isolation transformer 1 no. MCCB’s of required
rating along with SPD shall be provided. . Each PDU shall have hot swappable
units and monitor all power parameters for all racks and neutral current shall be
monitored collectively. It should be possible to add or replace circuit breaker
modules without switching OFF complete bus. Each breaker module should have
branch circuit monitoring. The digital LCD display should be provided to show
branch circuit current of panel of PDU. All copper cables shall be used for PDU
input and from PDU output to racks. Floor mounted PDUs shall be supplied with
built in SNMP card for remote network monitoring.
25

26. 8.10
DG System
i.
INTENT OF SPECIFICATION:
This specification covers the design, manufacture, assembly, shop testing, packing,
dispatch, Transportation supply, erection, earthing, laying exhaust pipes, outdoor
DG AMF panel, testing, commissioning, performance and guarantee testing.
Operation and Maintenance of Diesel Gen-Sets with canopy complete in all
respects with all equipment, fitting and accessories for efficient and trouble free
operation as specified here under.
Scope of Supply & Services
i.
General Scope of work shall include design, manufacture, shop testing,
packing, dispatch, transportation to site, supply, erection, testing and
commissioning, Operation and Maintenance of the following:
· Diesel engine complete with all accessories and Alternator directly coupled
to the engine through flexible/rigid coupling complete with all accessories for
starting, regulation and control, including base frame, foundation bolts etc.
interconnecting piping and accessories, power and control cable glands and
lugs. Engine will have command and control through respective controller &
equivalent. DG set should be silent type (Both engine and alternator will be
enclosed in canopy).
· Diesel Local/Remote control panel, DG control panel, and DG auxiliary
panel including power cables, control cables between other equipment and
special cables if any.
· Equipment necessary for fuel storing and distribution, day oil tank, piping,
pumps, valves, level indicators etc.
· Flexible connections & residential type silencer of exhaust system, including
thermal lagging and height of exhaust structure should be minimum 30
meters or subjected to applicable pollution control norms for all DG system.
DG exhaust structure, raising DG exhaust stack as per pollution control
board guidelines, thermal insulation of exhaust pipe and silencer.
· Battery stand to be fabricated with MS angle iron and battery charging
equipment, including their connections as necessary along with tools &
accessories for battery maintenance.
· Anti Vibration Mountings etc.
· Preparing all related shop drawings for approval from client/ consultant and
statutory bodies.
· Obtaining approval of the installation of Diesel Generators ( in canopy ) by
the Electrical Inspectorate and Pollution Control bodies and any other
statutory bodies. Carrying out performance and guarantee test including
making arrangements for loads etc. as required.
Codes and Standards
i. The equipment furnish under this specification shall conform to the following
latest standard, except where modified or supplemented by this specification:
a) BS:5514 : Specification for reciprocating internal combustion engine.
26

27. b) BS:5000 : Rotating electrical machines of particular type or for particular
applications.
c) IS:1239
: Mild steel tubes and fittings.
d) IS:1651 : Stationary cells and batteries lead acid type (with
positive plates).
tubular
e) IS:9224 : Specification of low voltage fuses, General Purpose.
f) IS:4540 :
equipment.
g) IS:5
Mono-crystalline semi-conductor rectifier assemblies and
: Colors for ready mixed paints.
h) IS:4722 : Rotating electrical machines
i) IS:1248 : Specification for electrical indicating instruments.
j) IS:10000 : Methods of tests for internal combustion engines.
k) IS:10002
l) IS:2147
:
Specifications for performance requirements for constant
speed compression ignition (Diesel) engine for general
purposes (above 20 kW).
: Degree of protection provided by enclosure for low voltage
switchgear and control gear.
m) IS:1600: Code for type testing of constant speed IC engines for general
purposes.
n) IS:1601 :
purposes.
Performance of constant speed IC engines for general
o) ASME Power: Internal combustion engines.
p) Test Code PTC-17
Diesel Engine
Diesel Engine, radiator cooled suitable for Generating Set application with
canopy and shall be selected on the basis of Prime rating, with an overload
capacity of 10% for one hour in any 12 hours of continuous operation. The
engine is equipped with rated alternator and having the following standard
accessories:
a)
Cooling System consisting of:· Thermostat & engine built pumps.
· Corrosion Resister
· Self contained piping.
· By pass thermostat.
· Radiator.
b)
Fuel System consisting of:· PT Fuel Pump
·
·
Fuel filters
·
c)
Injectors
Self contained piping & houses. Complete piping
Lubricating System consisting of:-
· Oil pump
27

28. · Strainer
· Lube oil cooler
· Oil filter
· Bypass filter
· Self contained piping
· Lube oil priming pump.
d)
Air Intake System consisting of:· Dry type filter
· Air intake manifold with necessary connections
· Turbocharger with after cooler.
e)
Exhaust System consisting of :· Exhaust Manifold
· Flexible piping
· Residential silencer
outside the canopy.
f)
to limit the noise level and extending silencer
Starting System consisting of :· Starter with suitable ampere capacity.
· Charging Alternator with inbuilt regulator as per battery capacity.
· Connecting links between battery & alternator.
g)
Coupling Arrangement consisting of:· Flexible coupling
· Flywheel
· Flywheel Housing
· Coupling Guard
h)
Instrument Panel consisting of:· Lube oil pressure gauge
· Water temperature gauge
· RMP Indicator & Hour Meter
· Battery charger ammeter
· Starting switch with key
· Lube oil temp. gauge
i)
Safety Control Trip for :· Low Lube oil pressure
· High Water temperature
· Engine Over speed
· Lube oil temperature
28

29. Alternator
a) Output: As per rated, self excited, self regulated foot mounted fitted with ball
and roller bearings and having PMG ( preferably), RTD, BTD, space
heater, REF CTs, 1 no. earth fault CT, droop CT for paralleling.
Alternator shall give full output at site ambient temperature. Alternator
shall be selected to deliver full output at ambient temperature + 10
degrees C rise.
b) Power factor : 0.8
c) Rated Generating Voltage : 415 Volts, 3 phase 4 wire system
d) Voltage regulation :+/- 1.5% all load between no load to full load & PF 0.8 to
unity.
e) Frequency : 50 Hz
f) Speed : 1500 RPM
g) Overload Capacity : 10% for one hour in any 12 hours of operation without
exceeding temperature rise limits specified in BS: 2613 when corrected to
ambient temperature at site
h) Class of Insulation
:H
i)
Space Heater : To be provided
j)
Winding connection : Star connection (all six leads will be brought out of stator
frame).
k) Termination
: Termination box shall be amended to match Cable
arrangement.
l)
Enclosures : Sound proof, drip proof & screen protected (minimum as per IP:
23). The alternator terminal box shall be amended and made suitable for cable
arrangement.
m) The alternator shall be self-excited, self regulated, self ventilated in brush less
for suitable automatic voltage regulator and shall conform to BS: 2613 or
equivalent standard and shall give rated output at NTP conditions. The
alternator shall have space heater which shall be connected with breaker
NO/NC contacts and this should be able to cut off with thermostat. Similarly
RTD and BTD shall be connected to temperature scanner.
Other Accessories
a) FUEL TANK
·
BASE FRAME
M.S. Fabricated adequately machined base frame complete with lifting, facilities
pre-drilled foundation holes suitable for permanent installation on foundation
shall also be supplied. The base frame shall be manufactured with steel and
shall be stress relieved. Manufacturer shall specify what measures are taken to
reduce the stresses.
b) BATTERIES
For electrical control circuit of 24V DC, suitable ampere hour battery and
charger complete with leads and wooden base plate and shall be placed inside
canopy.
c) FUEL SYSTEM:
· The engine shall be capable of running on all types of diesel fuel oil normally
available in India. Each DG shall have separate day tank.
29

30. · The fuel consumption of the engine at full, three quarters and half of its rated
power output shall be indicated by the DCSI in the bid.
d)
COOLING:
· The diesel engine should be water cooled with engine mounted radiator.
e) ENGINE GOVERNOR:
· The governor shall be of isochronous type to maintain zero speed rate or
regulation and shall be Al type as per BS:5514 in order to take care of heavy
motor starting. It shall have necessary characteristics to maintain the speed
substantially constant even with sudden variation in load. However, a tripping
shall be provided if speed exceeds maximum permissible limit. The governor
shall be suitable for operation without external power supply.
f)
TURBO CHARGER:
· It shall be of a robust construction, suitable of being driven by engine exhaust
having a common shaft for the turbine and blower. It shall draw air from filter
of adequate capacity to suit the requirements of the engine.
g) STARTER BATTERY:
· The battery shall conform to the requirement of IS:1651. Starting battery sets
of 24 V, heavy duty high performance approved make/quality shall be
provided to enable crank & start the engine even in cold/ winter morning
conditions below 2 Degrees Centigrade. Type/ voltage/ AH capacity of same
shall be on 20 hour rated discharge period . The battery should at least last
for 6 months shelf life..
· The battery shall be provided with good stainless steel stand painted with acid
proof black paint with min 3mm thick rubber mat below the battery.
· Batteries shall be of load container type only and not with PVC molded sealed
container so that each individual cells are available for individual monitoring
during its life span. Each cell shall be provided with electrolyte filling cap with
level floats for easy monitoring of electrolytic level.
· For each battery system following accessories shall be provided:
-
PVC Funnel - 1 No.
-
Small PVC mugs with handle- 2 Nos.
-
Hydrometer syringe type with float calibrated (not with zero markings
only) with one spare float.
-
Centre zero voltmeter good quality with 3V-0-3V scale.
-
PVC Jerry-can white color with tested quality distilled water, with can
clearly marked with engraved PVC inscription plate “Distilled Water”.
-
One tin of petroleum jelly (500 gms)
-
Painter brush 1” wide – 4 Nos.
-
The battery shall be provided with 2 Nos. cables, minimum 1.5m long
heavy duty rubber/ PVC insulated cabling with brazed tinned lug at
one end and with brazed tinned brass terminal lug at battery end - for
connecting batteries to cranking system - with 0.25 m long interbattery connecting cable.
30

31. -
The lugs shall be clearly stamped (+) or (-) and positive cable also red
sleeved for easy identification.
-
The batteries shall be supplied fully filled and first charge ready to
use.
h) BATTERY CHARGING SYSTEM:
· Float rate charging and quick rate charging system shall be provided at the
generator panel with appropriate bridge charger system, LC network, rate
selector switch and generously rated charging transformer and silicon one
rectifier bridge, so that the cranking battery system can be kept fully charged
at all times from E.B. supply network with quick charging rate limited to 0.8
times rated discharge current with provision in control transformer and Si
rectifier present to enable boost charging the battery at 2 times rated
discharge current in case of emergencies. To this and in the mode selector
switch boost charge position shall be present which however shall be kept
disconnected at mode selector switch normally.
· Two DC ammeters to clearly indicate float charging current & quick/boost
charging current shall be provided with 0-250 or 0-500 mA range & 15-0-15 or
30-0-30 Amps range respectively.
· The float charging ammeter circuit logic shall be so as to bring at in circuit
only on demand through a P.B. provided the R.S.S. (Rat Selector Switch) in it
float charging mode to prevent damage to the ammeter.
· Dropper resistor network on the load side of battery charger system shall be
provided so that higher charger voltages in quick or boost conditions does not
get impressed on the I/ L and Contactor coils, which voltage shall remain well
within +10% of rated voltage.
· Battery charging subsystem shall be designed for continuous operation at
cubicle ambient of 50 Deg. C corresponding to 45 Deg. C ambient outside
and should be designed to operate at 1.5 times rated maximum current
corresponding to boost charge current which can reach in practice as high as
2.5 times or 3 times rated discharge current.
· Any charger dynamo and dynamo charging current network present on the set
shall either have to be removed or made in operative so that both for AMF
and manual application the cranking battery system is kept charged from the
charger at the panels at all times during or shut down periods of the set.
· To the above and in case of manual DG sets, the input to charger subsystem
viz., 240 V AC is foreseen to be provided from other source in building
network from the portion that is normally supplied by manual DG Set during
DG operation or being fed by E.B. System.
i)
ENGINE SAFEGUARDS:
· Safeguards shall be provided and arranged when necessary to stop the
engine automatically by the following:
· Energizing a solenoid coupled to the stop lever on the fuel injection pump
rack.
· De-energizing the “fuel on” solenoid
· Energizing the “fuel - cut off” solenoid.
· If any of the door remains opens.
31

32. · The operation of the safeguard shall at the same time give individual warning
of the failure by illuminating an appropriate local visual indicator and remote
alarm at generator panel.
· The contactors, relays and other devices necessary for signal and control, for
above purposes shall be provided at Generator panel.
· At the set at a easily accessible place an “EMERGENCY STOP” mushroom
head stay put type P.B shall provided to stop the set in emergency mode.
· The safe guard to “STOP THE SET” shall stop the set irrespective of mode
selection of the set viz Auto, Manual or test for following cases, with
simultaneous isolation of alternator circuit.
· Emergency stop P.B’s operation
· Over speed.
· Low lube oil pressure.
· Earth fault and restricted earth fault of Alternator.
Specifications for outdoor, AMF, DG Panel, PLC Panel
Outdoor DG Panel, AMF, PLC Panel and Auxiliary panel
All the Panels (DG main panel) will be a outdoor type(suitable for outdoor duty), free
standing front operated, cubical in construction having multitier arrangement of the
incomers and outgoing feeders as per details given in the schedule of quantities. The
panels will have cable entry chamber at the bottom/top as per site conditions.
DCSI should provide the operation sequence of DG systems and LT system for mains
changeovers from DG system to Main & vice versa during the design stage for approval
by consultants/ Engineer in Charge.
a)
Selection of the components:
All the electrical components selected for constructing the various modules of
boards must have sufficient ratings to perform the duty they shall be required to
do consistently without any deterioration in their normal life and safety of the
other equipment including the safety of the operators. However these ratings
shall not be less than the ones specified in the bill of materials.
b) General arrangement and layout:
· General arrangement , fabrication, main bus bars of the panel and layout will
the same as specified in respective panel section except that it will be for
outdoor duty. All breakers will be EDO type in this panel.
c) TESTS PRIOR TO DESPATCH:
· Visual check for damage.
· Check equipments specifications.
· Checks all contacts, hardware.
· Continuity and earthing.
· Polarity of current transformers.
· Breaker mechanism and alignment.
· Breaker truck movement shall be free and smooth.
· Simultaneous closing of all poles in breaker.
· Megger test of all equipments for phase to phase, neutral to body, neutral to
earth and phase to earth. All megger tests shall give minimum 100 mega
ohms.
32

33. · Circuit drawings pasted inside panels
a.
All functional tests.
· Checking for all tightness of nuts and bolts.
· Insulation test at 3 KV for one minute.
· Alignment of doors, etc.
· High voltage test of 2.5 KV for one minute.
· Breaker racking in and racking out.
· Interlocking test.
· Clearances between phase and phase, phase and neutral to be tested.
Each DG cum change over outdoor Panel Shall have inbuilt AMF with load management
through PLC and kilowatt transducers in each panel.
i.
INCOMER :
a)
ii.
2 Nos. EDO, Four pole air circuit breaker with microprocessor based over
current, short circuit & earth fault relays with separate indications for each DG.
This shall be operated by local switch and remote through PLC in auto mode.
BUS BARS
a) Aluminum suitable to carry full load and suitable arrangement for incoming and
suitable SMC support to meet requisite fault level. The distance between
SMC/Fiber glass supports shall not be more than 400 mm. Outgoing terminals
shall be brought out for cable termination. The ratings of bus bars shall be as
per SLD.
b) The panel shall have complete facility of starting the DG manually both from
the panel & through PLC in auto mode.
iii.
INSTRUMENTS :
a)
1 No. 0-500 V analogue Voltmeter with selector switch & control
fuses.
b)
1 No. Analogue Ammeter with selector switch.
c)
1 No. Set Metering cast resin CTs of suitable burden (min 15 VA).
d)
2 Nos. Indicating lamps for set running / load on set.
e)
4 Nos. - Instrument Fuses.
f)
Complete microprocessor based AMF logic with LED indications for
different conditions of running, standby and load.
g)
1 No. Battery charger with D.C analogue voltmeter and ammeter for battery
charger.
iv.
OTHER AUXILIARIES
a)
Necessary aux. contactor for annunciation, indications for each DG.
b)
All control supply will be at suitable D.C voltage and suitable control
transformers shall be installed with protection on primary & secondary. This
shall be reliable control supply.
c)
ON/OFF start facility from panel in manual mode & indication for LOAD ON,
LOAD OFF. Indication for breaker ON/OFF TRIP. Indication for contactor
ON/OFF for each DG.
33

34. d)
Battery charger for suitable capacity with boost charging. Battery charger
shall be installed in such a way that exact 24V reaches the annunciation
panel.
e)
The exhaust fan, space heater shall be on 230 V A.C. and shall be derived
from control transformer located inside DG canopy.
f)
Master trip lockout relay.
g)
U/V, O/V, U/F, O/F, field failure relay, earth fault relay, RPR (active) and
RPR (reactive) for each DG. Microprocessor based three over current
element & one earth fault relay, standby earth fault definite min. time relay.
REF relay and earth fault relay will be external and all other protections
relays shall be inbuilt into Controller otherwise separate relay shall be
provided.
h)
Annunciator window for low Lube oil pressure, water temp, O/C, E/F, U/V,
RPR, O/V, U/F, O/F, REF along with test & reset push button at 24V D.C for
each DG. This shall be attached to buzzer. Lube oil pressure, high water
temp, O/V, O/F differential shall trip engine and other faults shall trip air
circuit breaker and annunciator window will be networked from power control
centre for engine and alternator parameters.
i)
Buzzer for each DG.
j)
All auxiliaries such as lube oil priming pump, canopy blower fans, and other
auxiliaries will start automatically in PLC or auto mode.
v.
All Control & power cables between engine and control panel.
vi.
Providing of space heater in all generators and they will be linked to Air circuit
breakers aux. contacts. Whenever ACB is ‘OFF’ then space heater will be put
‘ON’ & shall be controlled through thermostat. If ACB is On, space heater will
be switched Off.
vii.
Control panel shall have separate outgoing bay for outgoing cables as
mentioned in design, EDO air circuit’s breaker for both incoming and outgoing
breakers shall be provided.
viii. The panel will be dust proof, vermin proof confirming to outdoor duty
protection class and will be manufactured & enclosed with 2 mm thick CRCA
sheet. Abase channel of minimum 100 mm shall be provided at the bottom.
ix.
MANUAL MODE
a)
x.
In this mode, the required DG shall be started manually from AMF panel. All
protections specified above will remain in manual mode also.
AUTOMATIC MODE
a)
This is fully automatic mode in which the DG set starting command will come
from AMF circuit and stopping command will come from voltage sensing relay
in incomer breakers. Load management scheme through PLC shall be
installed along with kilowatt transducers in both DG incomers to automatically
switch ON/OFF DG’s as per the load. Initially two DG’s will start and after
starting both DG’s PLC will shut off one DG if load is less than 40% on both
DGs.
b)
The system shall allow the operator to select the start-up sequence for DG
starting.
c)
The starting/ stopping of DG Auxiliary feeders of respective DG’s shall also
be controlled by PLC.
34

35. d)
xi.
The DG start sequence can be pre-selected by the operator.
AUTOMATIC STARTING AND STOPPING OF ENGINES
a)
b)
xii
On sensing of Grid failure the PLC/Controller shall (after a settable time delay)
issue the start command to all engine, if the DG set does not start in the first
cranking, two more cranking attempts shall be made. Even then if the Engine
fails to start, then “ENGINE FAILS TO START” alarm shall be generated and
PLC shall proceed with starting the next DG in sequence selected.
After the DG set has been started and put on load, the PLC shall continue to
control its voltage and frequency PLC/ Controller shall also continuously
monitor the DG loading. If the loading exceeds a settable limit, (after a time
delay), the next DG shall be started to prevent DG Overloading. This process
shall also be there for shutting of the DG’s if load is less.
Testing
a)
All DG’s shall run individually on NO LOAD & FULL LOAD successfully without
any problem in manual and PLC mode separately.
b)
Adjust droops for PLC mode for speed & voltage. All testing and maintenance
charts shall be displayed in DG House along with operating instructions to
operators.
c)
Sharing of equal loads in each generators with auto start, auto load sharing
relay, auto load management successfully for a minimum period of 7 days in
PLC/ Controller mode. There shall be extensive training of personnel for 15
days during and after commissioning. Proper training chart will be prepared
prior to any training.
d)
The alternator of each type and rating shall be type tested for the following
tests as per IS:4722, IEEE 115 & BS:5000.
a) Temperature rise test on full load at factory
b) Momentary overload test at factory
c) Over speed test at factory
d) High voltage test at factory
e) Insulation resistance test (both before and after high voltage test) at factory.
f)
Measurement of polarization index at factory.
g) Noise level and vibration at factory.
h) The control panels shall be tested/checked for following (but not limited to):
i) Compliance to drawing, data sheet and this specification.
ii) Check for workmanship, wiring, and conformity to functional requirements.
iii) Calibration of instruments, meters C.T., P.T. etc.
iv) H.V. test.
v) I.R. test before and after HV test.
i)
The acceptance and routine tests of battery shall be done as per relevant
standard.
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36. j)
k)
Routine Test: All engines shall be subjected to routine test as per IS:10000.
Erection, testing, commissioning and performance tests
i. The entire work of erection, testing and commissioning of equipment supplied
under this package shall be carried out by DCSI and performance and guarantee
tests to be conducted at site are also included under the scope of this
specification..
ii. All special tools and tackles and spares required for erection, testing and
commissioning of equipment shall be supplied by the DCSI.
iii. Erection, testing and commissioning manuals and procedures shall be supplied,
prior to dispatch of the equipment.
The DCSI shall ensure that the drawings, instruction and recommendations are
correctly followed while handling, setting, testing and commissioning the
equipment.
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