| 摘要 |
A current transformer is provided to immediately check the generation of disconnection when manufacturing the earth leakage breaker, ELCB, GFCI, AFCI, the electronic type watt-hour-meter, and so on by using the current transformer or using the current transformer. The current transformer(CT) including the self-diagnostics inside is composed of a low-pass filter unit connected to both a current transformer(12) and ends of the current transformer, a differential amplifier unit(13) amplifying the differential voltage generated in the output line of the low-pass filter area, a comparison unit(14) outputting the signal of the high level if the output of the differential amplifier is lower than the reference voltage set up in advance, and a disconnection display lamp(LED) serially connected to the output terminal of the comparison unit to the switching element to indicate the disconnection of the current transformer according to conduction of the switching element.
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