Ground fault protection type electronic tripper tripping device

Abstract

The invention discloses a ground fault protection type electronic tripper tripping device, which is characterized in that a power supply isolation device is connected between an output end of a current-voltage switching circuit and an input end of a low dropout linear regulator (LDO) on the basis of an existing single current transformer (CT) ground fault protection type electronic tripper tripping device, and an isolation type trip circuit is adopted as a trip circuit. By adopting the scheme, the power supply isolation device is connected between the output end of the current-voltage switching circuit and the input end of the LDO, thus realizing isolation of ground potentials between a microprocessor and the current-voltage switching circuit. The ground potentials between the microprocessor and the current-voltage switching circuit do not share a common reference point, thus a signal processing circuit is not required to use a high-accuracy difference amplifier to process signals, and a common amplifier can process current signals including ground signals. The high-accuracy difference amplifier is extremely more expensive than the common amplifier, therefore, the electronic tripper tripping device is lower in the overall cost.

Description

technical field [0001] The invention relates to the field of electrical equipment, in particular to a circuit breaker for cutting off current, and in particular to an electronic release of the circuit breaker. Background technique [0002] Molded case circuit breakers are plastic case circuit breakers. It can be used to switch on and off the load circuit, and can also be used to control the motor that starts infrequently. Its function is equivalent to the sum of some or all of the functions of the knife switch, over-current relay, voltage loss relay, thermal relay and leakage protector. It is an important protective device in the low-voltage distribution network. [0003] The electronic molded case circuit breaker uses transformers to collect the current of each phase and compares it with the set value. When the current is abnormal, the microprocessor sends a signal to make the electronic tripper drive the operating mechanism. [0004] The electronic release of the mo...

AI Technical Summary

Problems solved by technology

This kind of circuit design uses the CT current vector sum of each phase to sample the ground signal. However, due to the single CT design, there is no common reference point between the current signal ground and the power ground, and a differential op amp must be used to realize the ground signal. However, the requirements for the operational amplifier are very high, and a high-precision special differential amplifier must be used to ensure that the signal waveform is not distorted.

[0007] To sum up, the non-ground fault protection type product has simple design and low cost, but its functions are less, which can no longer meet the needs of specific customers; two-wire Although the coil-designed product has grounding protection, it must use a double-coil CT, and the CT is large in size and high in cost, and the practical application may be limited; Differential amplifier, high cost, complex circuit structure

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