METHOD OF MONITORING PHASE LOSS IN THREE-PHASE NETWORK AND DEVICE TO THIS END Russian patent published in 2009 - IPC H02H3/24 

FIELD: electricity.

SUBSTANCE: proposed method of monitoring phase loss in a three-phase network and device for realising the method relate to electrical engineering and are used in circuits of automatic protective devices. The method is based on determining instantaneous values of line voltage as a difference of instantaneous values of phase voltage, measured relative a formed neutral point. The monitored three-phase voltage is stepped down, rectified, smoothed out, and a given voltage level is formed. Voltage across the neutral point is stepped up to a given level relative the common point of the circuit and the period of the phase voltage is determined from transitions through the given level. Phase loss is determined from the value of asymmetry coefficient, calculated as a ratio of root-mean-square values of reverse and forward sequence voltage, using root-mean-square values of line voltage. The device is realised by a device which has leads for connection to a voltage source, a three-phase rectifier, smoothing capacitor, resistors, operational amplifiers, capacitors, ADC and a processor.

EFFECT: highly reliable protection of three-phase equipment.

3 cl, 7 dwg