"DC Fan" fan in FG, RD, PWM, CT, SS, respectively, refers to what? FG: Frenquency generator (speed detection signal); RD: Rotate detection (rotation detection signal); PWM Pulse width module (PWM); CT: Autoshutdown atuorestart (locked from the start); SS: Soft Swich (soft handover ). "DC Fan" generally, which has several operating voltage, respectively, in what kind of END Customers ? 5V ---- NB; 12V ------ DT or VGA etc; 24V ------- OA or Severs sys; 18V ------- electromagnetic oven; 48V --------- other industrial application. Fan applications often hear dead center (point) What does it mean? Refers FAN power on by an external force FAN blades stop at some point, but after the withdrawal of external forces, the blades can not continue to rotate, but at this point is often referred to fan dead. Customer acknowledges fan test or production process which usually test? Production process: Low-voltage start, lock-in test, burn-in test different sound test, test current waveform. "DC Fan" Test recognition: ON / OFF, high and low temperature aging test, lock-in test.