Failsafe AC voltage supply for loads - has constant voltage transformer and control unit which couples failsafe bus=bar to standby current source via switching device

摘要

A fail-safe busbar is connected through a first switch and an a.c. controller with a transformer to a.c. mains, and through a second switch to a standby supply unit. A control device monitoring the mains voltage so controls the switches and the standby supply unit that the busbar is connected to the mains when its voltage is within the specified tolerances. If the voltage is outside the tolerance limits, the busbar is connected to the standby unit ready to deliver power. The a.c. voltage controller stabilising transformer is motor driven. The control device connects the busbar through the second switch to the standby supply unit, when the rate of change of the mains voltage exceed the speed of the variable transformer control.