AC voltage monitor for emergency switch over - has six-branch diode bridge coupled via transformer into AC line

摘要

The a.c. voltage monitor, for emergency-supply switch over systems, has the voltage being monitored coupled via a transformer and RC circuit to a six-branched diode bridge. In addition to the voltages from the transformer, the bridge is supplied with a six-pulse signal from a generator across one of the bridge's diagonals. A voltage proportional to the voltage being monitored is applied across the bridge's second diagonal, and a voltage shifted in phase by 60 deg. w.r.t. the first voltage is applied to the bridge's third diagonal. The vector difference voltage results across the bridge's fourth diagonal.