Connecting and disconnecting DC supply voltage to/from load e.g. cable car or press requiring high degree of safety, by closing relay after semiconductor switch has closed to connect supply

摘要

The method involves connecting the supply to the load by closing a semiconductor switch (8) in a first step, and in a second step that is time-offset from the first step, a relay (6) contact is closed. To disconnect the supply from the load, the relay contact is opened in a third step, and then a semiconductor switch is opened in a fourth step that is time-offset from the third step. An Independent claim is included for an apparatus for connecting and disconnecting a DC supply to a load.