Voltage detection leakage protection device for electric water heater

Abstract

The invention discloses a voltage detection leakage protection device for an electric water heater, which comprises a main switch, a leakage current mutual inductor, a leakage detection circuit, an optical coupler, a threshold voltage detection circuit, a protective execution circuit and a mechanical release / attracting device, wherein the main switch comprises a live wire switch, a zero wire switch and a ground wire switch respectively; the leakage detection circuit and the protective execution circuit are electrically connected between a live wire and a ground wire respectively; the leakage current mutual inductor detects leakage currents on the live wire and a zero wire, and sends information to the leakage detection circuit; a neon tube of the optical coupler is electrically connected between the zero wire and the ground wire and detects a threshold voltage difference between the zero wire and the ground wire; a photoresistor of the optical coupler is electrically connected with the threshold voltage detection circuit; the leakage detection circuit and the threshold voltage detection circuit send information to the protective execution circuit; and the protective execution circuit controls the mechanical release / attracting device to control turning on and turning off of the main switch. The voltage detection leakage protection device is simple in structure, convenient to use, and high in stability and reliability, and saves a large amount of material cost.

Description

technical field [0001] The invention relates to a voltage detection type leakage protection device for an electric water heater, in particular to a voltage detection type leakage protection device for a water storage type electric water heater. Background technique [0002] The leakage protectors on the existing market all use current detection type leakage protection devices, which can not only realize the function of cutting off the power supply and load when the loop current of the live wire and the neutral wire to the ground wire is greater than 5mA, but also realize the function of the live wire and the ground wire. When the neutral line current reaches 30mA, the power supply and load will be cut off within 0.1s, but its circuit is a current detection type leakage protection device, which cannot 100% guarantee the safety of users and property. In addition, the current detection type leakage protection device mainly has the following shortcomings that cannot be overcome:...

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Problems solved by technology

[0003] ① There are two kinds of national electricity environments, namely, protective grounding and protective zero connection. No matter which connection method is used, there is a part of the voltage of the socket ground wire and the neutral wire circuit voltage. This voltage exists objectively, and the national standard GB_20044- 2005 stipulates that when the circuit current in the mobile residual current device (PRCD) without overcurrent protection for household and similar electrical accessories reaches 30mA, the power supply and load must be cut off within 0.1s, and the grounding resistance is generally less than 0.1 Ω, that is to say, it is mandatory that the voltage of the ground wire and the neutral wire loop must be 30mA*0.1Ω=0.001V, and there is a certain voltage difference between the socket ground wire and the neutral wire loop voltage. In fact, different power supply systems generally have a voltage below 10V This voltage exists objectively. At this time, the loop current between the neutral wire and the ground wire must be greater than 30mA, so the current detection type three-wire leakage protector must disconnect the power supply. and the water pipe circuit for insulation (generally use plastic red and blue water pipe joints and liner insulation hangers), so that the current of the ground wire and the neutral wire circuit is less than 30mA, so as to prevent the leakage protection device from tripping by mistake and avoid affecting the use, but relatively The voltage of the E-N socket has been increased, and the voltage of the E-N socket is generally maintained above 64V and even reaches 90V. This voltage has seriously threatened personal safety;

[0004] ②Connect plastic red and blue water pipe joints to the output end of the water storage electric water heater to increase the water resistance and reduce the loop current of the ground wire and the neutral wire. At the same time, it is also necessary to increase the insulation device between the inner tank and the outer shell of the electric water heater, which will consume a lot of cost ;

[0005] ③Increasing restrictions on existing related patents on the insulation device of the inner liner and shell of the electric water heater lead to the situation of exclusive supply of the insulation device, which is not conducive to the development of the enterprise

[0006] At present, no company can solve the above problems, leading to a situation that is not conducive to self-development

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