| 摘要 |
An electrical safety circuit powered by an electrical power supply at point A terminal, the safety circuit includes a plurality of switches serially connected to one another, the serially connected switches have a first and second ends, the first end is connected serially to the power supply and the second end is serially connected to a safety circuit bypass detector having two ends, one end of the safety circuit bypass detector is connected serially to the second end of the serially connected switches and the second end of the safety circuit bypass detector is connected to a point B terminal, the point B terminal is connected to an electrical load. The safety circuit bypass detector have a switching device RX with a normally open contact RX1 and a normally close contact RX2, a switching device RZ with a normally open contact RZ1 and a normally open contact RZ2. |
| 主权项 |
1. An electrical safety circuit powered by an electrical power supply at point A terminal, said safety circuit comprising:
a plurality of switches serially connected to one another, said serially connected switches have a first and second ends, the first end is connected serially to said power supply and the second end is serially connected to a safety circuit bypass detector having two ends, one end of said safety circuit bypass detector is connected serially to the second end of said serially connected switches and the second end of said safety circuit bypass detector is connected to a point B terminal, said B terminal is connected to an electrical load; said safety circuit bypass detector have a switching device RX with a normally open contact RX1 and a normally close contact RX2, a switching device RZ with a normally open contact RZ1 and a normally open contact RZ2;
wherein, in normal operation when said switches are operated in a close position, switching device RX is energized causing closing of the normally open contact RX1 and opening of the normally closed contact RX2; switching device RZ is prevented from being energized since normally open contact RZ1 and normally closed contact RX2 are in open state; Whereby, from point B in respect to ground 52 an electrical signal transferred to said electrical load; In the event that at least one of said serially connected switches is malfunction, switching devices RX and RZ are in off state causing contacts RX1 and RZ1 to be in open state, thereby, a signal is not transferred from point B in respect to ground to said electrical load; contact RZ2 in this event is in open state thus, an electrical load controller not receiving a signal from a terminal SX. |
