| 摘要 |
An electrical power system to provide a selected voltage to a load such as a fluorescent lighting system is characterized by a winding 3 having a positive end connected to a positive rail and is tapped at a predetermined position for supplying an output terminal with a selected voltage. A first relay contact can electrically connect a neutral end of the winding to a neutral rail to provide one selected voltage or a second relay contact can electrically short-circuit a predetermined number of turns of the winding in response to a request for a second selected voltage. When a fault condition is monitored, a third relay contact can electrically short-circuit the neutral end of the winding to the predetermined position to put the system into a failsafe condition which prevents turns of the winding being open circuit.
|
