Procedure for recognizing failure of phase of converter- controlled three phase induction machine

摘要

A procedure for recognizing the failure of a phase of a converter-controlled three phase induction machine has monitoring of at least two phase currents in each monitoring stage of a monitoring circuit, which generates a trigger signal for the state of being below a threshold value for the concerned monitoring stage. In a first monitoring state in each monitoring stage, the instantaneous value of the phase current is compared with the threshold and during its state of being below, the trigger signal is generated. After that with a trigger signal waiting for attention, there is change from the first into a second monitoring state and in this state the duration of the trigger signal is compared with the angle swept by the voltage vector of the phase turning with the rotating field. With the waiting for attention of the trigger signal over a specified rotating field angle, there is change over into a third monitoring stage. Here the waiting for attention of the trigger signal during a defined delay time interval is tested and with its survival, phase failure is announced by the trigger signal.