Protector for preventing three-phase power circuit from generating high voltage

Abstract

The invention relates to a protector for preventing a three-phase power circuit from generating high voltage. The protector comprises a power circuit, a break and zero detection circuit and a control and output circuit. The protector comprises five input ends L1, L2, L3, N and PE and three output terminals 01, 02 and 03, wherein the terminals 01 and 02 are respectively connected with control terminals 01 and 02 of a tripping coil L of a power switch K. In the protector, a resistor R1, a neon tube HL1, a capacitor C1 and a neon tube indicator light HL2 are connected in series, wherein one end of the serial structure is connected with a zero line N1 end to be detected, while the other end is connected with the grounding electrode PE; the output of a photoresistor RL is subjected to voltage division through a resistor R2, delayed by a capacitor C2, shaped through a Schmitt trigger IC and then output through three pins; a normally open contact J1-1 of a relay J1-1 is controlled to be connected through a diode D1; and after the electromagnetic tripping coil L is energized, the power switch K linked with the electromagnetic tripping coil L cuts off the power so as to effectively prevent three-phase power from generating the hazards of high voltage entrance and achieve the purpose of protecting electric equipment.

Description

technical field [0001] The invention relates to a low-voltage three-phase power supply protection device, in particular to a protector for preventing high voltage generated by a three-phase power supply circuit when the zero line of a three-phase four-wire or three-phase five-wire low-voltage power supply is disconnected. Background technique [0002] At present, my country's general industrial and civil low-voltage power supply is a three-phase four-wire system or a three-phase five-wire system, namely A phase (fire wire), B phase (fire wire), C phase (fire wire), N neutral wire (zero wire) , Add a protective ground wire PE. Through protectors, controllers (switches, circuit breakers, etc.) connected to the device case. Since power lines, protectors, controllers and electrical equipment have been working in an environment that is vulnerable to air corrosion, oxidation, humidity, dust, surge, overvoltage, and undervoltage for a long time, the electrical contact of the prote...

AI Technical Summary

Problems solved by technology

Since power lines, protectors, controllers and electrical equipment have been working in an environment that is vulnerable to air corrosion, oxidation, humidity, dust, surge, overvoltage, and undervoltage for a long time, the electrical contact of the protector or controller will often be damaged. Point ablation or poor contact, short circuit or open circuit, wires and terminals loose or burnt out, etc., resulting in disconnection of the phase or neutral wire of the power supply, that is, the phenomenon of phase loss and zero loss of the three-phase power supply

Three-phase power supply zero-missing fault: In a three-phase unbalanced connection load, the neutral point is directly connected to the neutral line N, the neutral point and the neutral line N to the ground line PE normal voltage is 0V, the neutral point and the neutral line N The normal voltage of the live wire ABC is AC 220V. When the neutral line N of the power supply terminal is disconnected, that is, when the three-phase power supply is missing zero, the neutral line N of the disconnected part divides the power supply through the load and then rises, so that both ends of the load bear the voltage U Rapidly rising, greatly exceeding the normal working rated voltage range of 220V AC of ordinary single-phase electrical appliances, and the electrical equipment used is burned, especially the vast majority of civilian electrical appliances are single-phase power electrical appliances, so the lack of zero power failure is very important to thousands of households. It is commonly known as "high-pressure household entry", which happens from time to time. Through Internet search and market research, there is no publicized effective product and method to prevent "high-pressure household entry".

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