| 摘要 |
The invention is a safety device for an electrical apparatus that comprises an input (1) that is connected to an external power supply as well as an output (2) to which the electrical apparatus is connected. Phase leads are arranged to electrically connect the output (2) to the input (1). Each phase lead contains a normally open relay contact (4R, 4S, 4T). The contacts are closed when power is supplied to the relay (3). The relay's (3) supply circuit contains the switch contact (6) of a time switch (5) that can be manually activated. The switch contact (6) closes the relay's (3) supply circuit when the time switch (5) is activated. The relay's (3) supply circuit also contains a time circuit (7) controlled by the activating current of the relay (3). This is normally closed, but opens when continually actuated for a predetermined amount of time by the relay's (3) activating current so that the supply circuit is opened and the relay (3) is without current. The time circuit (7) then has an opening time that is longer than the time switch's (5) maximum adjustable connection time, which means that the time circuit will interrupt the power supply to the relay (3) if the time switch does not interrupt the power supply to the relay (3) due to a fault.<IMAGE> |
