Question

Give the details of switchyard 220 kV CB, Isolator, CT, CVT and lightning arrestor.  

Answer 1

220 kV SF6 Circuit Breaker

1. Make – ABB

2. Air pressure blocking a. Close Block – 17.3 bar.

b. Open block – 16.7 bar.

c. Auto reclose block – 19 bar.

3. SF6 pressure block a. Alarm – 5.2 bar.

 b. Rated – 6 bar.

 c. Limit – 5 to 6 bar.

d. Open block – 5 bar

4. Weight of gas / pole : 20 kgs.

5. Closing time : 130-milli sec.

6. Method of closing : Electro-pneumatic.

7. Compressor pressure : 20.5 kg/cm2.

Isolator

1. Type : High-pressure pressure relieving isolator (HPPR) central pole double

break.

2. CB and Isolator clearances : Phase to Phase – 4500 mm.

 Phase to earth – 2300 mm. 

Current transformer

1. Make : TELK made hermetically sealed.

2. Type : Single pole dead tank.

Capacitor voltage transformer (CVT)

This is capacitive potential divider and inductive medium mineral oil sealed.

ABB. make 245 kV/110 √3 V.

3 cores for metering and protection.

Lightning arrestor

Type : WS surge arrestor of ZODIVER type and SMX style.

Gapier zinc oxide arrestor. Multi unit construction for transport, storage and erection.

Rated voltage : 216 kV rms.

Operating voltage : 184 kV rms.