| 摘要 |
PURPOSE:To lengthen the cycle of periodic inspection and to reduce malfunction due to surge resistant noise by incorporating A test function, by dispensing with an exclusive tester and by making it possible to test without tripping while prodection continues. CONSTITUTION:A test function is implemented by a switch 12 to apply a test signal from a test signal generation circuit 11 generating the test signal to an amplification circuit 4, a switch 13 to apply the test signal to an operating value comparison circuit 7 and display circuits 8 and 9. Now, when the test signal is generated from the test signal generation circuit 11, the switch 12 only is closed and a, performance test on a characteristic circuit 5 side is performed. Then, the switch 12 is opened, while the switch 13 only is closed, and a performance test on the operating value comparison circuit 7 side is performed. In a periodic test, etc., switches 12 and 13 are closed at the same time and the performance tests on the characteristic circuit 5 side and on the operating value comparison circuit 7 side as well as a final output contact test are performed. |
