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Home > Leakage Current Detector
M54123B Datasheet






The UTC M54123B is a semiconductor integrated circuit with

amplifier for a high-speed earth leakage circuit breaker.

For the amplifying parts of earth leakage circuit breaker, the

UTC M54123B consists of differential amplifier, latch circuit and

voltage regulator.

In normal operating, the UTC M54123B should be connected to

the secondary side of the ZCT (zero current transformers). Here

the ZCT detects leakage current different amplifiers’ both input.

Then the signals which have been amplified are integrated by

an external capacitor. The integrated signal connects to the input

terminal of latch circuit whose output is suitable for the

characteristics of high- speed earth leakage circuit breaker.

Until the input voltage reaches the fixed level, latch circuit

doesn’t become high. Then drives a thyristor which is connected to

latch circuit’s output terminal. Once the trigger latch circuit, only the

power on again to reset.




* With good input sensitivity current temperature characteristics

* High input sensitivity : VT=6.1mV (Typ.)

* Only need low external component count

* High noise and surge-proof

* Low power dissipation : PD=5mW (Typ.)

* May be used both as 100V and 200V.

* Wide temperature range : from -20°C to +80°C

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