适用于：要求随负载的性质逐级调速的各种传动机械如机床、矿山、冶金、纺织、印染、化工等行业。Applications:widelyusedinsuchindustrywhichhavestepchangesofrotationalspeedtomeettherequirementsofloadcharacter,asmachinetools,mining,metallurgy,textile,printinganddyeing,chemicalindustryandagriculturalmachinery,etc.特点：采用改变绕组的接法来变换电机的转速和输出功率，使其与机械设备的负载特性相匹配，简化了变速系统，高效、节能。Features:simplifyspeed-changingsystemsbychangingtheconnectiontoobtaindifferentoutputandspeed.变速方案：双速、三速、四速Pole-changingmode:double,threeorfourspeed