Automatic phase-failure zero-failure power-off protection device

Abstract

The invention provides an automatic phase-failure zero-failure power-off protection device which mainly comprises an automatic shunt excitation breaker and a plurality of control relays. Two switching circuits composed of contacts of two control relays in a combination mode provide two power supply return circuits for a shut excitation coil. When phase failure and zero failure do not exist, the two switching circuits are both in the disconnected state, no current passes through the shunt excitation coil and power is normally supplied. When phase failure and zero failure exist, one of the two switching circuits is connected, the shunt excitation coil is energized and the automatic shunt excitation breaker trips to conduct power-off protection. When a shell of a distribution box is energized, the third control relay is energized, a normally-closed contact of the third control relay is disconnected, the return circuit where the normally-closed contact is located is disconnected, the action effect is equal to that of the situation that phase failure and zero failure occur, the shunt excitation coil is energized, and the automatic shunt excitation breaker trips to conduct power-off protection. The automatic phase-failure zero-failure power-off protection device has the advantages of being simple in structure, few in used part, high in reliability, low in cost and the like.

Description

technical field [0001] The invention relates to a circuit protection device, in particular to an automatic power-off protection device for phase loss and zero loss in a three-phase four-wire power supply line. Background technique [0002] In the low-voltage power distribution three-phase four-wire line, there are long-term safety hazards caused by power supply equipment line disconnection (phase loss, zero zero) failure, resulting in damage to electrical equipment and electrical appliances; low-voltage power distribution three-phase four-wire system In the system, the neutral line is generally grounded repeatedly, and the power supply box and the distribution box must be equipped with ground electrodes on the spot. When the wire is broken and the continuity of the grounding electrode is poor, or even the grounding has already been disconnected, the following safety hazards will occur: some single-phase 220V circuits will become 380V, causing electrical equipment and applian...

AI Technical Summary

Problems solved by technology

[0002] In the low-voltage power distribution three-phase four-wire line, there are long-term safety hazards caused by power supply equipment line disconnection (phase loss, zero zero) failure, resulting in damage to electrical equipment and electrical appliances; low-voltage power distribution three-phase four-wire system In the system, the neutral line is generally grounded repeatedly, and the power supply box and the distribution box must be equipped with ground electrodes on the spot. When the wire is broken and the continuity of the grounding electrode is poor, or even the grounding has already been disconnected, the following safety hazards will occur: some single-phase 220V circuits will become 380V, causing electrical equipment and appliances to burn out in a short time; three-phase power 380V Due to the unbalanced voltage of the circuit, the power of the motor drops, and the high temperature burns out in a short time

[0003] Existing phase failure and phase sequence protection relays (XJ3, XJ3-G, XJ5) and other types of products can automatically trip and power-off protection against power supply phase failure (it uses AC contactor voltage loss tripping or automatic circuit breaker belt failure) Voltage tripping device), there is no protection for the lack of zero line of the power supply, and because there is generally no automatic closing device once the contactor or circuit breaker trips, it needs to be manually operated on site, which does not meet the requirements for reliable and continuous power supply

At present, the three-phase four-wire system of the low-voltage distribution network (power supply box, distribution box) does not have the function of automatic power-off protection for phase loss and zero zero, and its technology is currently blank

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