THREE-PHASE MULTI-REIGNITION PHENOMENON DURING 40.5 KV VCB SWITCHING OFF SHUNT REACTORS

摘要

Detailed statistics and analysis were carried out on the field test in a substation on 40.5kV VCB switching off shunt reactor. Complex three-phase multi-reignition phenomenon occured in almost all the breaking operations. The whole reignition process could last for more than 5ms and can have 128 reignitions in one operation. The reignitions in three phases seems relatively independent to each other. The RRRV (the rate of rise of TRV) was extremely as high as 13.3kV/μs, and the interphase overvoltage could be 8.6p.u. which is far higher than the standards required. Through the analysis on the field test circuit, the 1 mechanism of the three-phase multi-reignition process was presented out. The magnitude of the prospective TRV, strong inter-phase coupling and forced arc extinguishing in VCB are the main causes of the complex process. The methods to evaluate the RRRV and the magnitude of TRV are given out. The inter-phase overvoltage can be twice in magnitude to the phase-to-ground one, and seriously threaten the inter-phase insulation of the breaker which can explain the accidents in practical application