Initial current reduction of synchronous motors with salient poles by static converters usage

摘要

The paper analyses the possibility of reducing the initial current of synchronous motor used for powering an excavator in an open coal-pit. The main generator group, which consists of three DC generators S = 1250 kW, reaches the torque moment through synchronous motor with salient poles usage, Sr = 1250 kW. The motor is accelerated as asynchronous squirrel cage motor, drawing attention to the machine acceleration period till the moment it enters synchronism. During this period, lasting up to 15 seconds, it is necessary to connect the rotor winding through a resistor, to start the acceleration as asynchronous motor and pull the machine into synchronism. After that, a synchronous motor powers the DC generators and operates as a synchronous compensator. The excitation circuits of electromotor were originally powered by the DC generators. Now, these systems are replaced by more efficient thyristor static converters. In this way, the excavator efficiency is increased, a faster response of excitation circuit is obtained and initial currents of synchronous motor are significantly reduced.