| 摘要 |
PROBLEM TO BE SOLVED: To provide a small safety device having a wide application range in which erroneous operation is eliminated while reducing voltage loss. SOLUTION: A power supply 17 and a load 18 are connected with feeder lines 19a and 19b, and a tripping unit 21 consisting of a normal close switch 22 and a latching relay 23 is arranged at the intermediate part of the feeder line 19a. In the safety device 1, terminals 4 and 5 connected with a resistor 16 are connected, respectively, with lines led out from the opposite ends 19-1 and 19-2 of a section b of the feeder line 19a having a predetermined wiring resistance, and a shunt current of the section b flows through the resistor 16. Since resistance of the resistor 16 is extremely low, heat is not generated from the load 18 by the shunt current but voltage drop across the section b increases as short circuit 25 occurs. A shunt current corresponding to the voltage drop flows through the resistor 16 to generate heat, and a heat responsive body 9 acts to close contacts 7 and 8. Consequently, the latching relay 23 acts to unlatch the normal close switch 22 thus opening the normal close switch 22 and interrupting the power supply current. COPYRIGHT: (C)2005,JPO&NCIPI
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