Transient Recovery Voltages During the Switching Under Out-of-Phase Conditions

Abstract

Out-of-phase synchronising occasionally occurs in power stations, one of the main reasons being wiring errors leading to particular out-of-phase angles of 60°el., 120°el. or 180°el.. The relevant standards IEEE Std C37.013 for generator circuit-breakers and IEC 62271-100 for high-voltage circuit-breakers consider only a maximum out-of-phase angle of 90°el.. From the well-defined TRV (transient recovery voltage) parameters for ?system-source faults? and ?generatorsource faults? also the TRV parameters for out-of-phase conditions can be deduced. This is done for three examples and the calculated TRV parameters are compared to those given in IEEE Std C37.013. For a 90°el. out-of-phase angle the rates of rise of TRV fit rather well; the calculated peak values are however smaller and the calculated out-of-phase switching currents are larger than given in IEEE Std C37.013. This standard does not at all cover the conditions at an out-ofphase angle of 180°el.. The situation seems to be still worse with IEC 62271-100 for high-voltage circuit-breakers.