由于同步电动机具有功率因数和效率较高、转速稳定、过载能力较大的特点,因此,对于大容量及没有调速要求的机械,一般采用同步电动机拖动。其中,采用同步电动机拖动的活塞式压缩机,已被广泛地应用于采矿、冶金、石油、化工、机械、建筑等工业部门。为了提高压缩机的单机生产能力,增大排气量,在不增加设备及压缩机强度等条件允许的情况下,采用提高机器转速是最简单有效的办法。对于采用同步电动机传动的大型活塞式压缩机,只要适当改变电动机的电极对数,便能提高机器转速。我国有的化肥厂,用提高同步电动机转速的办法来提高合成氨的产量,取 Because the synchronous motor has the characteristics of high power factor, high efficiency, stable speed and large overload capacity, the synchronous motor is generally used for the machinery with large capacity and no speed regulation. Among them, the use of synchronous motor-driven piston compressor has been widely used in mining, metallurgy, petroleum, chemical, machinery, construction and other industrial sectors. In order to improve the stand-alone compressor production capacity and increase the displacement, without increasing equipment and compressor conditions such as the strength of the permit, the use of increased machine speed is the most simple and effective way. For a large piston compressor driven by a synchronous motor, the machine speed can be increased by properly changing the number of motor pairs. Some fertilizer plants in China, with increasing synchronous motor speed approach to increase the output of ammonia, take