What inside a 11KV HT Switchgear Panel by Vacuum Circuit Breaker (VCB)?

What inside a 11KV HT Switch-gear panel by Vacuum Circuit Breaker (VCB):

11KV HT VCB is basically a electrically operated circuit isolating device. According to the common practice in Bangladesh, from 630KVA to 3150KVA substation, VCB is used as circuit isolator in the distribution system which is the main component of this cubical. A complete HT panel with VCB consist of following components i.e., 

1. 11KV Vacuum Circuit Breaker (VCB)

2. Earth switch

3. Potential Transformer (PT)
4. Current Tranformer (CT)
5. Protection Relay (IDMT, Restricted Earth Fault, Master Trip and So on)

5. Metering Unit

See below GA drawing of HT panel with VCB:



1. Vacuum Circuit Breaker: Vacuum Circuit Breaker is an indoor protection device used in distribution system and it is used to protect and control the circuit in normal load current, over load current and short circuit current condition.

2. Earth switch: Earth switch is used to ground the isolated circuit or bus for discharging the circuit. Earth switch provides more electrical safety for the personnel. 

3. Current Transformer (CT) & Potential Transformer (PT): CT & PT is used to reduce the Current and voltage respectively into a lower level from high level and provide this value to metering unit which are connected in the secondaries. 

4. Protection Relay: The purpose of the protection relay is to detect a problem, ideally during its initial stage, and to either eliminate or significantly reduce damage to personnel and/or equipment.

5. Metering Unit (V, A, KV): To show the supply values.