Three-phase four-wire electric energy meter capable of detecting its own faults

Abstract

The invention discloses a three-phase four-line energy meter capable of detecting self-fault, relating to the technical field of energy meters. The three-phase four-line energy meter can switch a partof load connected to a high-power phase line of the three-phase four-line energy meter to a low-power phase line of the three-phase four-line energy meter when the power connected to each phase of the three-phase four-line energy meter is not balanced. The three-phase four-line energy meter comprises a three-phase four-line energy meter body, comprising phases A, B and C, a null line N and a three-phase energy metering module, wherein the three-phase four-line energy meter further comprises a node J1, a controller as well as a three-phase balance monitor, a No. 1 voltage sampling circuit, a single-phase inverter power supply, a No. 2 voltage sampling circuit and an interface power monitor respectively connected with the controller; the power output end of the single-phase inverter power supply is connected with the power input end of an isolation transformer, the node J1 is connected with the power output end of the isolation transformer and the sampling end of the No. 2 voltage sampling circuit respectively, and the three-phase energy metering module is connected with the controller.

Description

technical field [0001] The invention relates to the technical field of electric energy meters, in particular to a three-phase four-wire electric energy meter capable of detecting self-faults. Background technique [0002] With the development of economy and society, there are more and more types of electrical equipment. Since the current power supply system is generally a three-phase power supply system, in the three-phase power supply system, if there is a large asymmetry in the power of the three phases, there will be unbalanced operation of the power grid, and there will be grid jitter. [0003] When the power grid is running in an unbalanced state, the transformer in the power grid is in an asymmetric running state. A transformer in an asymmetric running state will cause the zero-sequence current of the transformer to be too large, and the excessive zero-sequence current will cause the local parts of the transformer to overheat. If the temperature of some parts of the t...

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Problems solved by technology

[0007] The purpose of the present invention is to solve the problem that the existing three-phase four-wire electric energy meter does not have a phase-line switching function, so that when the power connected to each phase of the three-phase four-wire electric energy meter is unbalanced, it cannot be connected to the high-power phase of the three-phase four-wire electric energy meter. Part of the load on the line is switched to the low-power phase line of the three-phase four-wire electric energy meter, which provides a way to timely connect the three-phase four-wire electric energy meter when the power unbalanced on each phase of the three-phase four-wire electric energy meter occurs Part of the load on the high-power phase line of the three-phase four-wire watt-hour meter is switched to the low-power phase line of the three-phase four-wire watt-hour meter. The switching current is small, and the composite switch will not be burned out during switching. It can accurately detect the exact time point when the AC current crosses the zero point, and can also perform switching at the exact time point when the current crosses the zero point. It has a simple structure and a high degree of intelligence that can detect its own fault. Four-wire energy meter

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