Three-phase compressor phase reversal and loss protection device and method

Abstract

The invention relates to a protection device and a method for anti-phase / open-phase of a three-phase compressor, so as to solve the non-detection problem when the three-phase of the power supply of the compressor is reversely or erroneously grounded. The device comprises a three-phase compressor feed circuit, a three-phase voltage detection circuit, an anti-phase / open-phase detection circuit, a protection execution circuit, and a power supply circuit. The three-phase voltage detection circuit is composed of a diode rectification circuit bridged over the three-phase line and the ground and an optical coupling transistor circuit bridged over the two ends of the diode; the anti-phase / open-phase detection circuit is composed of a microprocessor input pin connected with the three output terminals of the three-phase voltage detection circuit, a triode relay circuit with the grid thereof connected with the output pin of the microprocessor, an anti-phase / open-phase sound alarm circuit and the power supply circuit; the protection execution circuit is composed of a contactor with the contact point connected with the feed circuit of the three-phase compressor in series and the damping coil thereof controlled by the contact point of the triode relay; and the power supply circuit is composed of the two-phase bridge type rectified, CR and filter circuit after being stepped down by the transformer in the three-phase power supply.

Description

technical field [0001] The invention relates to a three-phase power supply compressor, in particular to a reverse-phase-lack protection device and method for a three-phase compressor. Background technique [0002] Some air conditioners with large power, such as cabinet air conditioners, mostly use three-phase power supply, that is, 380V and 50HZ power supply. The motor in the compressor also uses a three-phase asynchronous motor. It consists of three-phase windings. They are evenly distributed on the stator at intervals of 120° and can be connected into a star or delta. When supplying power, three alternating currents with equal amplitudes and 120° phase angles are passed into the three-phase winding, as shown in the figure As shown in 1, the upper curve in the figure represents the change curve of the three-phase current U, V, W, (R, S, T) frequency amplitude, and the corresponding lower arrow is the direction of the instantaneous synthetic magnetic field generated by the ...

AI Technical Summary

Problems solved by technology

[0007] The present invention proposes a reverse phase and lack of phase protection device for a three-phase compressor in order to solve the problem that the reverse phase and lack of phase are difficult to detect in the existing three-phase compressors and the current three-phase anti-reversal printed circuit cannot detect all wrong connections. The method, the protection device includes: a three-phase compressor power supply circuit; a three-phase voltage detection circuit; a reverse phase loss detection circuit; a reverse phase loss protection execution circuit; The circuit consists of a step-down resistor connected between the three-phase wire and the ground, a diode rectifier circuit, a light-emitting diode connected across the two ends of the diode to receive the three-phase rectified voltage of the photocoupler transistor, and the two poles are connected to the DC power supply and the ground through a resistor. The input electrode is composed of a photosensitive transistor that receives light from a diode; its reverse phase loss detection circuit is connected to the three input pins of the microprocessor connected to the output of the three-phase voltage detection circuit through a resistor, and the collector is connected to the DC power supply through the relay coil. The pole is grounded, the gate is connected to the triode relay circuit of the output pin of the microprocessor, the sound alarm circuit is connected to the output pin of the reverse phase loss alarm of the microprocessor and the voltage dividing resistor between the ground, the DC power supply and the resistor is connected to the The DC power supply formed by the triode and voltage regulator tube between the power supply and the ground; its DC power supply is composed of two phases of the three-phase power supply, which are stepped down by a transformer, rectified by a diode bridge, and filtered by resistors and capacitors; The phase protection execution circuit is composed of contacts connected in series to the power supply circuit of the three-phase compressor, the brake coil connected in series with the contacts of the above-mentioned triode relay and the power supply, and composed of a three-phase contactor controlled by the above-mentioned triode relay contacts

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