Two sub-transmission lines from New Multan 500 kv and Vehari 132 kv feed into the Qasim-pur grid station. The main components in the grid station include current transformers, isolators, circuit breakers, tie breakers, bus bars, lightning arresters, potential transformers, and a capacitor bank. The control room houses measuring, controlling and isolating devices like relays, circuit breakers, meters to monitor amps, energy, and power factor. A battery room provides DC power to the controlling devices through a series connection of dry cell batteries.

1. Introduction to Qasim pur
grid Station

2. Qasim pur grid Station Overview
Two Sub-Transmission lines come to the Qasim-pur grid station
• From New Multan 500 kv---step down----132kv
• Vehari 132

4. Main yard:
• The area where substation’s equipments are installed.

5. Main components of grid station:
• Current transformers(CT).
• Isolators.
• Circuit breakers & tie breakers.
• Bus bars.
• Lightning arresters.
• Potential transformers(PT)
• Capacitor bank.
• Control room.
• Battery room.

6. Current transformers(CT).
• It is use for measuring current.
• In current measuring process we take some tapping from secondary
transformers, it give the minute value of current and scale of CT are
design according to this minute current (200/5).
• If we obtain 5A from secondary of CT then its scale indicate 200A
current at its primary.

7. Current transformers(CT).

8. Isolators:
• It is OFF load device.
• Actually it is a mechanical switch.

9. Circuit breakers & tie breakers:
• CB can be manual or automatic
• It use to connect and disconnect circuit in case of short circuit
conditions and normal conditions.
• Types.
• Air circuit breakers.
• Oil circuit breakers.
• Air blast circuit breakers.
• Minimum oil circuit breakers.
• SF6 circuit breakers.

10. Circuit breakers

11. Tie circuit breakers:
• It is use to energize and de energize bus bars

12. Bus bars
• Qasim pur grid station uses double bus bar scheme.
• Advantages;
• Reliable.
• Any CB can be take out of service for maintenance.
• Any bus can be take out of service for maintenance.

13. Bus bars:

14. Lightning arresters:
• It is like a protecting valves.
• It protect the grid station’s equipments from over voltages, surges
and lightning.

15. Potential transformers(PT):
• It is a step down transformers.
• It step down the incoming voltage up to the distributive requirement

16. Power factor improvement
Uses to maintain the power factor.
• Power factor improving techniques;
1. Capacitor bank.
2. Synchronous condensor.
3. Phase advancer.

17. Capacitor bank:

18. Tapping(available on transformer’s HV).
• it is used for voltage regulation according to requirement.

19. Control room:
• It consist of measuring, controlling and isolating devices.
• Following devices which are use:
• Relays(analogue & digital).
• Circuit breakers.
• Ampere meters.
• Energy meters(US Aid).
• Power factor meters.

20. Control room:

21. Battery room:
• It consist of Dry batteries, which are connected in series.
• Each battery act as 2V cell, in order to produce 110V, 55 batteries are
connected in series.
Importance:
• It is backbone of grid station, because all controlling devices operate
on DC supply, e.g relays, alarms, etc………………………

22. Battery room: