Statistical Analysis and Countermeasures of Under-voltage (No-voltage) Release Protection of Low Voltage Circuit Breakers

This paper presents the load loss statisties during auto-reclosure dead time and after backup power source switch operation, it points out that the operation of under voltage release of low voltage circuit breakers is one of main causes of power interruption. Even worse, it results in larger service area power outage especially for VIP customers' blackout with negative social effects. By investigating some typical cases, it is found that the under voltage release protection configuration in most user's low voltage circuit breakers is not vet7 reasonable and often is of poor protection setting coordination with that of the upper stage grids,h is suggested to study and formulate uniform technical standards and codes in accordance with power grids practical situation, to supervise guide the users for safer and more reliable power supply as well as decreases the load loss users' power outage.