CIRCUIT FOR PROTECTION OF THREE-PHASE INDUCTION ENGINES AGAINST DISSYMMETRICAL OPERATION AND OVERLOADS

摘要

1. A circuit for the protecting three-phase induction motors from asymmetric operation and loads, consisting of: a two-phase voltage sensor, inverters, reference potentiometer, power supply, and three-phase current/voltage converter having a reference output and a delay output, whereas the converter consists of three current/voltage transformers with star configuration windings, whereas the transformer windings are connected with inputs of a half-wave phase rectifier, whereas the windings' common point is connected via a resistor/capacitor parallel network with the half-wave three-phase rectifier input, and via a diode with the reference output connected to the reference potentiometer slider, characterized in that between the output (WY) of the two-phase voltage sensor (CN) and the base of the transistor (T) that controls the relay, the first inverter (NOT1), second inverter (NOT2) and resistor (R1) are connected, whereas the delay output (WZ) of the three-phase current/voltage converter (P) and the transistor (T) base, the third inverter (NOT3) and the first diode (D1) are connected, whereas to the third inverter output (NOT3), the input of the fourth inverter (NOT4) is connected, whereas the (NOT4) output is connected via (D2) and (R2) with (NOT3) input, whereas the third diode (D3) is connected between the (NOT3) input and the (NOT2) output.IMAGE