Three-phase voltage unbalance detector

Claim 1

A CIRCUIT FOR INDICATING ANY UNBALANCE WHICH MAY DEVELOP IN A THREE-PHASE BRIDGE RECTIFIER AS A RESULT OF THE VOLTAGE IN ONE OF THE THREE INPUT LINES TO THE RECTIFIER DROPPING APPRECIABLY BELOW ITS NORMAL VALUE, SAID CIRCUIT COMPRISING: (A) AN ENERGY-STORAGE DEVICE UPON WHICH IS DEVELOPED THE PEAK VOLTAGE OUTPUT OF THE RECTIFIER UNDER NORMAL OPERATING CONDITIONS (B) A PEAKING DIODE CONNECTED IN SERIES WITH SAID ENERGY-STORAGE DEVICE ACROSS THE OUTPUT OF SAID RECTIFIER, THE RIPPLE VOLTAGE OF SAID SYSTEM APPEARING ACROSS SAID PEAKING DIODE DURING NORMAL OPERATION (C) A RELAY THROUGH THE COIL OF WHICH CURRENT FLOWS DURING NORMAL OPERATION OF SAID CIRCUIT (D) A CONTROLLED SWITCH SHUNTING THE COIL OF SAID RELAY, SAID SWITCH HAVING A GATE ELECTRODE (E) MEANS FOR APPLYING A PORTION OF THE RIPPLE VOLTAGE WHICH APPEARS ACROSS SAID PEAKING DIODE TO THE GATE ELECTRODE OF SAID CONTROLLED SWITCH TO MAINTAIN THE LATTER IN OPEN CIRCUIT CONDITION DURING NORMAL OPERATION OF SAID CIRCUIT, AND (F) AN INDICATOR ENERGIZED UPON DEENERGIZATION OF THE COIL OF SAID RELAY, (G) WHEREBY UPON THE CREATION OF AN UNBALANCE IN SAID CIRCUIT AS A RESULT OF THE VOLTAGE IN ONE OF THE THREE INPUT LINES TO SAID RECTIFIER DROPPING APPRECIABLE BELOW ITS NORMAL VALUE, THE RIPPLE VOLTAGE DEVELOPED ACROSS SAID PACKING DIODE WILL INCREASE TO INCREASE THE VOLTAGE APPLIED TO THE GATE ELECTRODE OF SAID CONTROLLED SWITCH TO CAUSE THE LATTER TO CLOSE, THEREBY SHUNTING THE COIL OF SAID RELAY TO DEENERGIZE THE SAME AND SIMULTANEOUSLY ENERGIZE SAID INDICATOR.