Design and Simulation of Re-Ignition Circuit for Synthetic Testing of HV/EHV Circuit Breakers

Majority of the HV circuit breakers are SF6 filled puffer type, where the maximum arc duration will be more than one cycle. To prove the HV circuit breaker design as per national and international standards synthetic testing method is used. Re-ignition circuit plays a vital role during the synthetic testing when clearing the fault currents with maximum arcing times. This paper presents the design and simulations carried out on the re-ignition circuit, used in high power laboratory, CPRI Bangalore, during the synthetic testing of high voltage circuit breaker.

I. Introduction

More number of generating units are getting added to the power system network to meet the increasing demand, which increases the fault level of the network grid. Increased fault level needs robust protection, where high voltage circuit breaker plays a vital role. Testing of these circuit breakers to prove its design values is also challenging task for the high power laboratories. As the fault current and operating voltages increases, the required power for testing of these circuit breakers also increases. For example to test a 765kV 63kA single pole circuit breaker 60000MVA installed capacity is required. As of now in the India the maximum rating available for single short circuit generator is 2500MVA, to meet the 60000MVA, 24 generators of this capacity are required to run in parallel, which will have economical and operational difficulties. Testing this HV/EHV class circuit breaker by direct test method is having the following disadvantages. 1.

The very high installed capacities like more number of short circuit generators required.

2.

Installing these generators and running in paralleling is highly difficult and also not economical.

3.

Difficult to achieve the TRV parameter for testing of the circuit breakers