... /T8981-1999 ,IEC34-1 2. three-phase ac motor 3. safety usage STC series ac motor is used in town,countyside,worksites,villages and ... power source.The motors are drip-proof with rotary fieald type,IP23,Insulation Class:B or F,adopting harmonic excitation system ... operation and maintenance.The motors are three-phase,four-wire type,adopting star connection with neutral poin.The rated line voltage ...