Power source switching device with plural interlocking elements

摘要

A switch unit is movably arranged in a housing for selective connection of two power sources to a load circuit. When the switch unit is extracted out of the housing, one power source is connected to the load circuit via one by-pass switch unit arranged on the switch unit, thereby avoiding interruption of power supply. When such power supply from the one power source is interrupted, connection is automatically shifted to the other power source via the other by-pass switch unit arranged on the switch unit. When one by-pass switch unit is closed to connect one power source to the load circuit, one interlocking element movable with that by-pass switch unit stops one engaging element movable with one contact, thereby inhibiting concurrent connection of two power sources to the load circuit.