电动执行器故障的修理一例南阳酒精总厂仪表处李长玉故障现象：可正转。不反转。分析：既然可以正转。说明电源是正常的。故障只是反转电路不正常。检查（参见电路图）：（１）由转换开关（１－３）对“２”或“４”应有相同的电压（接近２２０Ｖ）为正常。如一端无电压。... Electric actuator failure repair a case of Nanyang Alcohol Factory Instrument Chang Changyu Fault phenomenon: can be transferred. Do not reverse. Analysis: Since it can be transferred. Description of the power is normal. The fault is only reverse circuit is not normal. Check (see circuit diagram): (1) It should be normal for the “2” or “4” to have the same voltage (close to 220V) by the changeover switch (1-3). If no voltage at one end. ...