1. test no less than two, one smoke exhaust fan control power prices, one observation fan operation, abnormal phenomenon immediately stop inspection; First check the direction of rotation is correct; blower process, you should check the operating current of each phase whether the balance, the current exceeds the rated current; if it is not a normal phenomenon, should stop checking. Exhaust fan running after five minutes, the fan down to check whether there is abnormal phenomenon, confirmed that no anomalies start running again. 2. The two-speed fan test, should be started at low speed, and check the direction of rotation is correct; the fan still must be renewed after the start-up speed, to prevent reverse rotation speed, causing the switch to trip and electrical damage. About two-speed motor; two-speed motors are extremely variable speed induction motor, the stator windings are connected by changing the way to achieve change in the rotating magnetic field of the stator pole pairs dtf exhaust fan fire, thus changing the motor speed. According to the formula; n1 = 60f / p shows asynchronous motor synchronous speed and inversely proportional to the number of pole pairs, doubling the number of pole pairs, synchronous speed n1 down to half the original speed two-speed exhaust fan fire price, also rated motor speed n will drop approximately half, so changing the number of pole pairs to achieve the purpose of changing the motor speed. This level of speed control method is not smooth speed control, and only applies to squirrel cage motors. htf exhaust fan price | White City exhaust fan | Chen Yu-conditioned factory outlets provided by Wu Cheng Chen-yu air-conditioning Limited. Wu Cheng Chen Yu Air Conditioning Equipment Co., Ltd. (www.wccykt.com) strong, credible, in Dezhou fan, ventilation equipment industry has accumulated a large number of loyal customers. The company better work attitude and constantly improving innovative ideas will lead Chenyu air conditioning and you hand into the brilliant, for a better future!