| 摘要 |
Method and apparatus for connection or disconnection respectively of a load circuit (L) in relation to an electrical alternating current supply network by means of an electro-mechanical switch element (R), such as a relay or contactor device, controlled by an electronic control circuit (SE) for the purpose of switching on or switching off at the instant when the mains or supply voltage or the load current has a zero crossing. Beforehand in the control circuit there is inserted and estimated time delay between application of control current to the switch element and the switching on or off thereof, based on given time parameters for the switch elements or drive voltage concerned. After having received a control signal (11) for connection or disconnection the control circuit applies control current (15) to the switch element (R) at an instant calculated from sensed zero crossing(s) and said estimated time delay. The control circuit (SE) is adapted to measure any time deviation between the actual zero crossing concerned and the real switching instant and thereby a real time delay for the switch element (R). Moreover the control circuit is adapted to store the real time delay for use in calculating an instant for applying control current at the subsequent connection or disconnection respectively or the switch element. |
