Phase sequence judging circuit based on asymmetrical three-phase circuit theory

A three-phase circuit and phase sequence judgment technology, which is applied in the direction of phase sequence/synchronous indication, can solve the problems of inconvenient operation, accuracy, unsatisfactory reliability and circuit cost, etc., and achieve the effect of easy implementation

CN102411096AInactive Publication Date: 2012-04-11CHANGZHOU JIEXUN ELECTRONICS
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2012-04-11
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention relates to a phase sequence judging circuit, in particular to a phase sequence judging circuit based on an asymmetrical three-phase circuit theory. The invention mainly aims to provide a circuit scheme which has the characteristics of reliability, accuracy, quickness, conciseness and low cost and is used for judging the phase sequence in a low-voltage three-phase power supply system. The basic content of the invention refers to a circuit special for judging the phase sequence in a three-phase low-voltage power supply system constituted on the basis of an asymmetrical three-phase circuit theory. The phase sequence judging circuit is in a photoelectric coupler output form or a relay output form, and comprises an asymmetrical three-phase input loop, a bypass resistor, a diode rectifier bridge, a filtering capacitor, an LED (Light-Emitting Diode), a photoelectric coupler or a relay and the like, wherein the asymmetrical three-phase input loop consists of a capacitor and a resistor.
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Description

technical field

[0001] The invention relates to a phase sequence judging circuit, in particular to a phase sequence judging circuit based on the theory of an asymmetrical three-phase circuit. Background technique

[0002] In many cases, electrical equipment has strict requirements on the phase sequence of the three-phase power supply, which cannot be connected incorrectly, that is, if the phase sequence of A-B-C is stipulated, it cannot be connected to the phase sequence of A-C-B or C-B-A, otherwise the equipment using three-phase power supply may It cannot work normally, such as: when the phase is wrong, the output voltage of the three-phase fully-controlled rectifier bridge becomes uncontrollable; the three-phase AC asynchronous motor will reverse and so on. In general, it is often difficult to confirm the phase sequence of the three-phase power distribution line, and once the phase sequence of the power supply line changes, the phase sequence must be re-determined. If a ...

Examples

Embodiment Construction

[0015] Asymmetrical three-phase circuits such as figure 1 As shown in (a), the figure assumes that:

[0016] X C = 1 ωC = R B = R C = R ( = 1 G )

[0017] G is the admittance, since X C It is a capacitive reactance, so the circuit load is asymmetrical, and the circuit is further transformed into a phase voltage source symmetrical (load asymmetrical) circuit, such as figure 1 (b) shown.

[0018] figure 1 The neutral point voltage in (b) (that is, the voltage between the neutral point of the load and the neutral point of the power supply) is

[0019] U · N , N ...