Japanese electrical equipment manufacturing company Mitsubishi Electric has developed a new circuit-interruption technology for railway power-supply systems.
The systems supply power to railcars from off-board locations. By detecting short-circuit faults instantly, the new high-speed direct-current (DC) technology isolates faulty circuits in a short timeframe.
Furthermore, it is expected to improve railway safety in terms of equipment protection, as well as operational stability for power-supply systems.
This technology overcomes two key problems and interrupts faulty current with better speed.
Initially, a conventional DC circuit breaker detects a faulty current through an electromagnet driven by the faulty current itself. The weight of the moving core cuts the time needed for fault detection.
The technology uses a lightweight core driven by an electromagnetic force, which is achieved with a new U-shaped conductor.
Mitsubishi's DC circuit breaker consequently takes less time from fault occurrence to contact separation.
Secondly, the breaker drives the arc generated between the contacts to the grid in order to close the high current.
Faster current interruption can be achieved with the new technology by using a new contact material and a rib-shaped contact that strengthens the electromagnetic force applied to the arc.
The technology suppresses the amplitude of a short-circuit current under standard value (55kA) and safely protects equipment.