| 摘要 |
PURPOSE:To make it possible to switch over safely to the measuring position with a simple operation by providing a switch between the earthing point and the grounded point at least at one end of a power cable while a measuring device is connected in parallel therewith by way of it. CONSTITUTION:A pair of measuring terminals 3 and 3' are grounded through switches 1 and 1' in place of an earth wire to be connected to a metal shield layer and led out from both ends of respective switches. Switches 2 and 2' are inserted into the non-earth position in the terminals 3 and 3'. When a power cable is used, the switches 1 and 1' are closed and the switches 2 and 2' opened. When diagnosing insulation, for example, the measuring device is connected to the terminal 3 and then, the switch 1' is opened while the switch 2 is closed. Thereafter, by opening the switch 1, measurement can be done on the one end side of the power cable. After the end of the measurement, everything is returned to the original condition by closing the switch 1 with the switch 2 opened and the switch 1' closed. Moreover, a device 3' is connected in the measurement at the other end of the cable.
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