Introduction to Qasim pur grid Station

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

Main yard:

• The area where substation’s equipments are installed.

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.

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.

Current transformers(CT).

Isolators:

• It is OFF load device.

• Actually it is a mechanical switch.

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.

Circuit breakers

Tie circuit breakers:

• It is use to energize and de energize bus bars

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.

Bus bars:

Lightning arresters:

• It is like a protecting valves.

• It protect the grid station’s equipments from over voltages, surgesand lightning.

Potential transformers(PT):

• It is a step down transformers.

• It step down the incoming voltage up to the distributive requirement

Power factor improvement

Uses to maintain the power factor.

• Power factor improving techniques;

1. Capacitor bank.

2. Synchronous condensor.

3. Phase advancer.

Capacitor bank:

Tapping(available on transformer’s HV).

• it is used for voltage regulation according to requirement.

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.

Control room:

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………………………

Battery room: