Abstract:

The current phase loss protections for three-phase asynchronous electric motors usually use the method of measuring the current of each phase through the current transformers, supplying 2 or 3 electromagnetic relays with its contacts connected in series in the control circuit of the motor to cut off the power supply to the motor when fault problems occur. The disadvantage of these protections is that they do not work reliably when the signals of the phase current amplitudes vary over a wide range. The paper presents a proposal to build a type of phase loss protection device according to the pulse principle, replacing the above protection with the advantages of reliable operation and can be used for many types of motors with high efficiency and different capacity.