| 摘要 |
PURPOSE:To realize stabilized power supply by making ineffective the output from an undervoltage relay, which receives the line voltages between a tripped phase and other sound phases at the time of single-phase reclosing, during no-voltage reclosing interval. CONSTITUTION:Upon tripping of phase R circuit breaker, for example, undervoltage relays UV-SRS, UV-STR for shaft circuit fault detection receiving line voltages of RS and TR function. But since the voltage vector of phase R is not within a predetermined range(In this case, it is about 30-45 deg. considering that alpha in 90+ or -alpha lead is higher than the phase voltage even if the line voltage between an interrupted phase and other phase is worst) with respect to the line voltage vector between phase S and T for the phase R trip command memory signal of first fault, tripping based on the outputs from the undervoltage relays UV-SRS, UV-RTR is blocked. According to the constitution, stabilized power supply can be realized without causing power interruption. |
