Uninterrupted Fast Switching Technology Between Power Supplies Based on Parallel Trigger Gap

Induction motors, frequency converters and other voltage sag sensitive loads (VSSLs) require that the power supply interruption time should not exceed 30 ms, otherwise the normal operation of the equipment may be affected. In order to guarantee the safe and stable operation of sensitive loads, this paper proposes a uninterrupted fast switching control method for dual power supplies based on the technical route of trigger gap in parallel with fast circuit breaker. This methodology has the advantages of simple structure, high reliability, and switching time of no more than 20 ms. Then the residual voltage characteristics after power loss of induction motors and frequency converters are analyzed, as well as the effect of power switching time on the inrush current of these VSSLs at the switching instant. Accordingly, an uninterrupted switching control strategy between power supplies with both fast switching mode and in-phase switching mode is given, which helps to significantly reduce the impact of voltage dips on the operation of VSSLs.