| 摘要 |
This invention relates to an electrically operated actuator for quarter-turn valves, such as butterfly or ball valves. The actuator includes a single phase 2-pole dynamo-electric machine comprising a stator having three windings and a rotor having a plurality of short-circuited windings. The rotor is coupled directly with the output shaft and the windings of the stator are energised from a power supply through respective limit switches which are cam controlled by the output shaft. One of the stator windings controls the final movement of the actuator in each direction of travel and the limit switch for this winding is broken to de-energize the winding by an adjustable stop mechanism. |
