Microcomputer protector of current mutual inductor

Abstract

The invention consists of an analog quantity collecting circuit, a central process circuit, a relay output circuit, an external port and a display circuit. Wherein, the analog quantity collecting circuit comprises a primary side external current transformer, a voltage transformer whose two ends at secondary side is connected to a sampling resistor, a low-pass filter circuit passing by voltage of sampling resistor, and an positive input end of operational amplifier. The operational amplifier adopts voltage tracing method, and its output is connected to the AD input of CPU in central processing circuit. The output of switching value of CPU is connected to the controlled end of short circuit relay at primary side through photoelectrical coupler.

Description

Technical field

[0001] The invention relates to a protection device for a circuit facility, in particular to a protection device for a current transformer. Background technique

[0002] Modern power systems have increasingly higher requirements for automation, especially automatic measurement and automatic control. According to the applicant's understanding, current transformers and voltage transformers are widely used in existing power systems to control current, voltage, and frequency (which can be measured by collecting AC voltage).

[0003] Generally, the protection of voltage transformers can be realized by leakage switches or air circuit breakers, which is relatively simple, while the protection of current transformers has not seen development for a long time. In fact, the open circuit of the current transformer is more serious than the short circuit of the voltage transformer. A short-circuit of the voltage transformer will burn itself at best, and an open current transfor...

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