For the safety and reliability requirements and characteristics like high frequent short-circuit current of the traction power supply system

a new fault current limiter with redundant protection topology is proposed.Two protection branches in parallel is design through an interlock switch

each of them can limit the fault current.The protection branch I is used as a normal operation protection

while a double shunt reactor shunt capacitor and a reactor are used to construct a parallel resonance loop.The protection branch II is connected with the reactor in parallel with an ultra fast switch.Under normal operation condition

the protection branch I is put into operation and the branch II is used for hot standby.The main controller controls the switching of the branch II through real-time monitoring of the system current and the state of the protection branch I.Test results of the prototype show that the current limiter can monitor the fault current and action before the operation of the circuit breaker

and can limit the over current to the maximum extent.