The main task of the traction substation (open and close, zoning pavilion) is to supply power to the contact network. Installed in the traction substation (open and close, partition pavilion) within the circuit breaker "trip" in addition to the traction substation (open and close, partition pavilion) itself equipment failure (the proportion of this case is very small), caused by the "trip" of the short-circuit current mainly from the contact network.
Contact network in the uninterrupted operation of the state, the contact network of electric locomotives under the non-stop implementation of the busy transportation tasks, as well as transportation, public works departments of the joint coordination. Any accident may affect the contact network, so that the circuit breaker "trip".
Expanded:
The safe operation of the traction power supply system, which delivers power to electric locomotives, should be ensured.
In the event of an accident, the relay protection device installed in the traction transformer substation (opening and closing office, zoning booths) will be activated by the short-circuit current generated by the accident, and will automatically disconnect the circuit breaker supplying power to the point of the accident, so as to narrow down the scope of the accident, and to ensure the safe operation of other equipments and the normal supply of power to the non-accidental lines.
References:
Baidu Encyclopedia-Tripping