... exceeding 55V AC, so as not to damage the module2.GND:DC power cathode3.A+,A-:Stepping motor one winding 4.B ... :1.When ambient temperature is high or working current over 3A, fix the module on big metal shell , or use axle flows ... not be damaged, but the electrical machinery runs abnormally, shake , and output is small.Please check whether the wiring of electrical machinery is ...