Transient Characteristic Analysis of Induction Motor at the Bus Transfer by Standby Power Source in the Blackout

Abstract

This paper discusses currently used bus transfer methods, and presents a new method to successfully perform fast bus transfer to connect to the standby power source in the event of a supply disruption. Generally, the load of the induction motor is equipped with two independent power supplies to increase the stability of the power supply. If main power source supplies become unavailable due to a power outage, the standby power source connected in parallel is designed to operate. When blackouts occur, the voltage drops to a very low value in a very short time, but the current hardly flows immediately. When a voltage drop occurs due to the blackout, the speed of the motor starts to decrease. When the power is supplied by the standby power source, it is necessary to keep the torque level at a safe level because a large current may cause a serious excessive torque to the motor shaft. The induction motor requires stable power supply at all times during operation of the load. In this study, we propose a method to reduce current and torque by providing a current signal instead of a voltage signal as a breaker input signal in order to quickly switch the backup power source in the event of the blackout.