... -friendly 2,brushless stamford alternator 3,competitive price ST Series Single-phase synchronous alternator 1,safe,environment-friendly 2,brushless stamford alternator ... ,etc. 3) Rated frequency: 50 / 60Hz 4) Rated speed: 1,500 / 1,800rpm 5) Three-phase four-wire 6) Protection: I5P21- IP23 ...