关键词：变电抗器；软起动器；晶闸管；感应角度
摘 要：When an industrial induction motor is started directly, the stator current is generally 5-7 times greater than the rated one, which makes the voltage sag of the transmission lines increase rapidly, furthermore, affecting the power quality seriously. However, applying variable reactance type motor soft starter to start motors, the starting current of the motor can be reduced effectively. The mathematical model of the soft starter which is based on variable reactance is established, and the relationship between the thyristor conduction angle and the motor current is analyzed. The purpose of the motor and equipment's protection is achieved by selecting the appropriate conduction angle to control the starting current amplitude.