HIGH-VOLTAGE CIRCUIT BREAKER

PROBLEM TO BE SOLVED: To provide a method capable of electrically separating vehicle units in an underfloor work.SOLUTION: In a formation vehicle configured by coupling vehicle units, power supply units of the vehicle units are electrically connected with each other through a high-voltage through circuit threaded in the vehicles configuring the formation vehicle. To the high-voltage through circuit, a high-voltage circuit breaker disconnecting the power supply unit between the respective vehicle units is installed. The high-voltage circuit breaker is configured by a vacuum circuit breaker blocking power feeding to the power supply units; and a mechanical circuit breaker connected to the vacuum circuit breaker and disconnecting the plurality of connected power supply units. The high-voltage circuit breaker is configured to open and close an apparatus box installed under a floor of the vehicle and covering the mechanical circuit breaker. The mechanical circuit breaker is handled in an underfloor work.