Combined with the action recording of protection device

an accident in which multiple sets of protection devices act at the same time is analyzed. The explosion takes place in the voltage transformer of incoming switch line in a substation

and this causes the simultaneous action of the line protection of this interval and line protection of adjacent interval as well as line protection of the upper substation and backup protection in the main transformer. Because the protection coordination seems unreasonable

the fault waveform and the protection action are analyzed and discussed in depth. It is found that during this fault

there are many times of shortcircuit fault conversion

there is no problem in the cooperation of various protection devices

and the protective devices acted correctly.