Automation of compressor units driven by a synchronous motor

Abstract

Synchronous motors are currently started at both full and reduced voltage. 4 Regardless of the method used for starting a synchronous motor, the rotor of the latter, in addition to the excitation winding powered by a normally direct current, is also equipped with a short-circuited starting winding, which during the starting period turns the synchronous motor into an asynchronous one with a squirrel-cage rotor with the starting properties inherent in this motor. Both of these rotor windings, not being electrically connected to each other, during the start-up period represent, as it were, two independent secondary circuits participating in the creation of the torque developed by the engine. When the engine is running at full (synchronous) speed, the short-circuited starting winding plays the role of a damper winding. The synchronous motor can be started either at full or at reduced voltage. This article discusses the operations of automatic control of compressor units driven by a synchronous motor, which is started at full voltage; automatic protection of these installations from possible accidents is also provided.