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8/2/2019 Electrical Services Factby Ashutosh Kumar
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ELECTRIALSERVICESSYSTEMFACTSSubject –BUILDING ANDINFRASTRUCTURESERVICES
Submitted by:-
Ashutosh Kumar M.B.E.M (2nd
Sem.) S.P.A New Delhi
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FUNDAMENTALS
1. Electricity can be generated using the kinetic energy of water, heat energy of
the sun and coal, or from the nuclear energy released from the fission of
nuclear fuel.
2. There are mainly following types of power plant for electrical current
generation :-
Coal based thermal Power Plants
PNG/CNG based thermal power plant
Nuclear Power Plants
Hydro Power Plants
Solar Power Plants
The Wind Power Plant,
Tidal Power Plant
Geothermal Power Plant
Hydel power plants
3. Major Electrical Equipment used in Power Plant are Generation Equipment,
Transformers, Switch Gear, Protection of Electrical Systems.
4. At the generating plants the energy is produced at a relatively low voltage between
about 2.3 kV and 30 kV, depending on the size of the unit. The generator terminal
voltage is then stepped up by the power station transformer to 400kv supplied to Grid
for transmission for whole country.
5.Transmitting electricity at high voltage reduces the fraction of energy lost toresistance. For a given amount of power, a higher voltage reduces the current
and thus the resistive losses in the conductor.
6. There are following different range of standard voltage available for electrical
supply :- 12V, 24V, 110V, 220V, 400-440V, 660V, 1100V, 11000V, 22000V,
33KV, 66KV, 110KV, 220KV, 400KV, 600KV, 1000KV.
7. 12V & 24V are extra low voltage 110V called low voltage 220V- 1100V called
medium voltage and above that are High voltages. Up to 220 voltage Single
phase and above that 3 phase voltage available.
8. In Overhead transmission line, suspension insulators contain a chain of
several disks each rated about 22kv. By multiplying 22 by the number of disks
we can get a good estimation of the voltage in the transmission line.
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SUBSTATION&SWITCHYARD
9. Substation constitute of HT meter, HT panel, Step down transformer and LT
switch board (which connects to LT Panel).
10. For supply of 11kv, 22kv and 33kv one substation required, but for largerprojects where supply voltage is 66kv or 132 kv then two level of substation
required.
11. Minimum size required for switchyard is 60mX40m with 6m road all around.
The space can be reduced with the use of gas insulated circuit breaker.
12. The site selection criteria for switchyard should be:
a. As near the load center as possible.
b. As far as possible rectangular or square in shape for ease of proper orientation of
bus– bars and feeders.
c. Far away from obstructions, to permit easy and safe approach / termination of high voltage overhead transmission lines.
d. Free from master plans / layouts or future development activities to have free line
corridors for the present and in future.
e. Easily accessible to the public road to facilitate transport of material.
f. Preferably fairly leveled ground. This facilitates reduction in leveling expenditure.
g. Above highest flood level (HFL) so that there is no water logging.
13. For control points we provide Automatic circuit breaker and manual Isolators.
These are of three types. Oil filled type, Vacuum type and SF6 type.
14. Provision of adequate earthling system in a Sub Station is extremelyimportant for the safety of the operating personnel as well as for proper
system operation and performance of the protective devices.
15. Transportation and unloading of the sub-station material and equipment at the
location shall be done in a safe manner so that they are not damaged or
misplaced. And inspection required to avoid use of any damaged to insulator
or other fragile equipment due to excessive swing.
16. There are two options available for substation in any building on ground with
the any edge (preferably rear) of the site, or in the Basement. In case of
basement only dry type appliance used in the substation.
17. Right arrangement of components in any substation is as follows :-
C.B
Transformer
DG setsMeter room HT Panel
Isolator
L T panel
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18. All door openings from substation, electrical rooms, etc should open towards
outside.
19. The power supply control to any such substation or transformer (located at
basement levels or upper floors) shall be from a location on ground floor/first
basement level having direct access from outside so that in case of fire, the
electrical supply can be easily disconnected.
20. The minimum height of high voltage switchgear room shall be 3.6 m below the
soffit of the beam.
21. enclose any part of the substation, which is open to the air and contains live
equipment which is not encased, with a fence or wall not less than 2.4 m in
height to prevent, so far as is reasonably practicable, danger or unauthorised
access.
22. Sufficient safety signs of such size and placed in such positions as are
necessary to give due warning of such danger as is reasonably foreseeable inthe circumstances.
23. In case of connected load of 100 kVA and above, the relative advantage of
high voltage three-phase supply should be considered. Though the use of
high voltage supply entails the provisions of space for the capital cost of
providing suitable transformer substation.
24. These are the following advantages are gained by HT line:
Advantage in tariff.
more effective earth fault protection for heavy current circuits; Better control of voltage regulation and more constant supply voltage.
25. It shall be mandatory to provide power factor improvement capacitor at the
substation bus. Necessary switchgear/feeder circuit breaker shall be provided for
controlling of capacitor bank of desired capacity.
TRANSFORMER26. There are two types of transformer available Oil filled type and Dry type.
27. General design objective while selecting the transformer(s) for a substation
would be to provide at least two or more transformers, so that a certain
amount of redundancy is built in, even if a standby system is provided.
28. Minimum separation between two transformers is 2.5m, if provided less than
that they should be separated by firewall.
29. Transformers should be placed on slightly above to ensure no flooding
generally 150mm above placed.
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30. In case of oil filled type transformer base platform must have channel drain to
ensure removal of leaking oil.
31. In case of transformer placed on ground surrounding area should be hard
paving or covered by stone pebble to stop any vegetation and creeper.
32. General requirements for transformer (Tx) room
• Minimum headroom (for equipment & delivery)
• Fire services installation
• Space for maintenance/removal
• Next/Close to main switch room
• No expansion joint & other engineering services
• Independent ventilation
• Generally, no more than 3 Tx in one room
33. Additional requirements for plant room / Transformer room
• A separate & independent staircase to G/F• Also a protected lobby
• Sum pit w/ sump pumps to extract water when flooding
• Hoist beam with pulley for 8,000 kg
• Damp proof course (prevent moisture)
• No dead ends in periphery of the transformer or panel.
34. Major equipment in Transformer rooms
o Power transformer
o Switchgear
May be other equipment like
o LV switchboardo LV capacitor bank
o Battery & charger
o Marshaling boxes
o Meter panel
35. Minimum space around transformer should be 750 mm.
36. Single phase transformer comes in 5kvA, 10kvA, 25kvA and three phase
transformer comes in 63kvA, 100 kvA, 125 kvA, 160 kvA, 200 kvA, 250 kvA,
320 kvA, 400 kvA, 500 kvA, ………….3200 kvA, 4000 kvA.
CABLES ANDBUSDUCTS37. Cable, Armoured — A cable provided with a wrapping of metal (usually in the
form of tape or wire) serving as a mechanical protection. It is used for ouside
underground cabling.
38. Cable, Flexible — A cable containing one or more cores, each formed of a
group of wires, the diameters of the cores and of the wires being sufficiently
small to afford flexibility.
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39.
40.
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44.
45.
HTP
46.
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