Neutral line breaking protection device

Abstract

The invention discloses a neutral line breaking protection device. Voltage between three phases of lines of an three-phase alternating current circuit and a neutral line is monitored through a first overvoltage relay, a second overvoltage relay and a third overvoltage relay respectively. When the neutral line is broken, at least one of the first overvoltage relay, the second overvoltage relay and the third overvoltage relay will monitor voltage larger than a second preset voltage value, and then the corresponding overvoltage relay is closed, so that the switch control part of a circuit breaker bears voltage larger than the first preset voltage value, the switch control part controls a switch to be opened, and an electric appliance on the user side is powered off. By the adoption of the neutral line breaking protection device, when the neutral line is broken, a power supply access of the electric appliance can be turned off, so that damage caused by neutral line breaking on the electric appliance is reduced, and power supply system reliability is improved.

Description

technical field [0001] The invention relates to the field of electric power detection, in particular to a neutral line disconnection protection device. Background technique [0002] At present in our country, almost all the generation, transmission and distribution of electric energy adopt three-phase alternating current, and the power supply mode is three-phase four-wire system. It can be known in theory that the neutral line current is zero only under the condition of symmetrical load in this power supply mode. [0003] However, in practical applications, since the load of each phase is different, the three-phase load cannot be symmetrical, and the current of each phase is also different, so the neutral line has current. If the neutral line is disconnected for some reason under the condition of load asymmetry, the voltage of a certain phase will increase or decrease significantly, up to 380V, and the lowest can be lower than 100V. Using electrical appliances can cause gr...

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Problems solved by technology

[0003] However, in practical applications, since the load of each phase is different, the three-phase load cannot be symmetrical, and the current of each phase is also different, so there is current in the neutral line

If the neutral line is disconnected for some reason under the condition of load asymmetry, the voltage of a certain phase will increase or decrease significantly, the highest can reach 380V, and the lowest can be lower than 100V. Using electrical appliances can cause great harm

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