Minus time-delay disconnection type earth leakage protection circuit

Abstract

The utility model relates to a minus time-delay disconnection type earth leakage protection circuit, a power supply input end of the circuit is provided with a reset key and a trip coil, an input end of the trip coil is also connected with an output end of a solid-state relay, and an input end of the solid-state relay is connected with a control electrode of a silicon controlled rectifier SCR1. The control electrode of the silicon controlled rectifier SCR1 is further connected with a leakage protection module, the reference voltage reference end and the input end of the first isolation amplifier are connected with a divider resistor and a temperature sensor respectively, and the output end of the first isolation amplifier is connected with a charging delay circuit and the input end of a second isolation amplifier. The charging delay circuit comprises a resistor and a timing capacitor, the reference voltage reference end of the first isolation amplifier is also connected with a divider resistor, and the output end of the second isolation amplifier is connected with the control electrode of the silicon controlled rectifier; according to the utility model, the low-temperature leakage protector for protection can be continuously and manually operated for emergency use for a certain time, and the difficulty that hot water cannot be used in the early stage of temperature loss of the electric heating faucet is avoided.

Description

Technical Field

[0001] The utility model relates to a protection circuit for an electric water heater, in particular to a sub-zero time-delay disconnection type leakage protection circuit. Background Art

[0002] When a low-temperature protection type leakage protector is used in an electric water faucet location, it will enter a protection state when the temperature in the water pipe reaches below zero, making the electric water faucet difficult to use. However, it takes a certain amount of time for ice to form in this state. During this period of time, the electric water faucet cannot be used, causing inconvenience to the user. Therefore, it is necessary to provide a protection circuit that can continue to be used during the timed period and can continue to be used for an emergency for a certain timed period if it is still needed after the positioning period, so as to solve the shortcomings of the low-temperature protection leakage protector in this scenario. Utility Model Content

[0003] The utility model aims to provide a sub-zero time-delay disconnection type leakage protection circuit, which solves the problem that the existing low-temperature protection leakage protection circuit directly stops heating at the initial stage of low temperature.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] The utility model provides a sub-zero time-delay disconnection type leakage protection circuit, wherein a reset button is arranged on the live wire and the neutral wire of the power input end of the circuit, a trip coil is connected to the reset button, the input end of the trip coil is also connected to the output end of the solid-state relay, the input end of the solid-state relay is connected to the control electrode of the thyristor SCR1, the control electrode of the thyristor SCR1 is also connected to the leakage protection module, and is characterized in that it also includes a first isolation amplifier and a second isolation amplifier, the reference voltage reference end and the input end of the first isolation amplifier are respectively connected to a voltage divider resistor and a temperature sensor, the output end of the first isolation amplifier is connected to a charging delay circuit and the input end of the second isolation amplifier, the charging delay circuit includes a resistor and a timing capacitor, the reference voltage reference end of the first isolation amplifier is also connected to a voltage divider resistor, and the output end of the second isolation amplifier is connected to the control electrode of the thyristor.

[0006] Furthermore, the input end of the solid-state relay is also connected to the output end of the first isolation amplifier.

[0007] Furthermore, a diode is provided between the output end of the second isolation amplifier and the control electrode of the thyristor, and the output end of the second isolation amplifier is connected to the anode of the diode.

[0008] Furthermore, the timing time of the timing relay is not higher than 60 minutes.

[0009] Furthermore, the minimum temperature threshold of the temperature sensor is no higher than minus 1 degree Celsius.

[0010] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0011] Compared with the existing low-temperature protector, the sub-zero time-delay disconnection type leakage protection circuit of the utility model is powered on. When the temperature reaches the minimum threshold or below, the temperature sensor will transmit the output end of the first isolation amplifier. Once the voltage is higher than the reference voltage reference end, the timing capacitor will be charged. When the charging reaches the timing time, the first isolation amplifier will transmit a high voltage to the second isolation amplifier. When the voltage at the input end of the second isolation amplifier is greater than the reference voltage reference end of the second isolation amplifier, the output end of the second isolation amplifier will output a high voltage to the control electrode of the thyristor SCR1, so that the thyristor SCR1 is turned on and tripped to achieve low-temperature delay protection. In the tripping state, press the reset button to continue charging the timing capacitor. After it is full, it will continue to output a high voltage to turn on the thyristor SCR1. The utility model solves the problem that the low-temperature leakage protector that enters the protection can continue to be used for emergency for a certain period of time by manual operation, avoiding the dilemma that the electric water faucet cannot use hot water at the initial low temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0013] Figure 1 It is a circuit diagram of Embodiment 1 of the utility model;

[0014] Figure 2 yes Figure 1 Schematic diagram of the enlarged structure at point A.

[0015] The reference numerals are described as follows:

[0016] 1. Power input terminal; 2. Trip coil; 3. Reset button; 4. Solid-state relay; 5. First isolation amplifier; 6. Second isolation amplifier; 7. Voltage divider resistor; 8. Temperature sensor; 9. Charging delay circuit; 10. Diode. DETAILED DESCRIPTION

[0017] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] like Figure 1 As shown, a reset button 3 is provided on the live wire and the neutral wire of the power input terminal 1 of the circuit, and a trip coil 2 is connected to the reset button 3. The input end of the trip coil is also connected to the output end of the solid-state relay 4, and the input end of the solid-state relay 4 is connected to the control electrode of the thyristor SCR1, and the input end of the trip coil 2 is connected to the output end of the solid-state relay 4; the solid-state relay 4 is used to control the action of the trip coil 2, and the action of the trip coil 2 will cause the leakage protection module to be also connected to the control electrode of the thyristor SCR1. In a normal state, the reset button 3 is closed, the trip coil 2 works normally, and the power supply supplies power to the load normally. When leakage occurs, the leakage protection module will quickly feedback to the control electrode of the thyristor SCR1 to turn it on, and the control electrode of the thyristor SCR1 will transmit information to the solid-state relay 4, and the output end of the solid-state relay 4 will output a signal, so that the trip coil 2 is tripped and disconnected, and then the reset button 3 is popped open, so that the power supply no longer supplies power to the load.

[0020] like Figure 2As shown, it includes a first isolation amplifier 5 and a second isolation amplifier 6. The reference voltage reference end and the input end of the first isolation amplifier 5 are respectively connected to a voltage divider resistor 7 and a temperature sensor 8. The temperature sensor 8 is used to sense the internal temperature of the water pipe of the electric hot water faucet. When the temperature is greater than a certain value or lower than a certain value, a larger voltage is transmitted to the input end of the first isolator. At this time, the voltage of the input end is greater than the reference voltage reference end, which will cause the output end of the first isolator to output a high voltage. After the high voltage is output, it first reaches the charging delay circuit 9. The charging delay circuit 9 includes a resistor and a timing capacitor. The timing capacitor is charged through the resistor. The charging time of the timing capacitor is not more than 60 minutes. In this example, 60 minutes is selected. The reason is that if the selected time is too long, the low-temperature protection type faucet will be used continuously for too long at a low temperature, causing damage. If the selected time is too short, it may not meet the user's use requirements. After charging is completed, since the temperature sensor 8 is still outputting a high voltage, the high voltage will reach the output end of the second isolation amplifier. After the output end of the isolation amplifier receives the high voltage, once it is higher than the voltage of its own reference voltage reference end, it will output a high voltage to the thyristor SCR1 through the output end of the second isolator, so that the thyristor SCR1 is turned on, and then the trip coil 2 is tripped, and the reset button 3 is disconnected. No more power is supplied.

[0021] The output end of the first isolation amplifier 5 is connected to the input end of the solid-state relay 4, the power input end 1. In this way, when the reset button 3 pops up, that is, after 60 minutes, if it is still needed to be used, press the reset button 3, the first isolation amplifier 5 and the second amplifier will be in working state, and will still output a high voltage through the output end of the first isolation amplifier after the timing capacitor is fully charged, and then turn on the thyristor SCR1 through the second isolation amplifier 6, so that the reset button 3 pops up.

[0022] A diode 10 is arranged between the output end of the second isolation amplifier 6 and the control electrode of the thyristor, and the output end of the second isolation amplifier 6 is connected to the positive electrode of the diode 10, so that the current between the second isolation amplifier 6 and the thyristor SCR1 can only flow in one direction, avoiding damage to the second isolation amplifier 6 when the protector leaks.

[0023] In this example, the lowest temperature threshold of the temperature sensor 8 is not higher than minus 1 degree Celsius, that is, when the operating temperature is lower than or equal to minus 1 degree Celsius, the temperature sensor 8 will transmit a high voltage to the input end of the first isolation amplifier 5. The reason for setting it at minus 1 degree Celsius is that at this temperature, freezing problems will occur more quickly and the device has to be stopped after 60 minutes, but it is also for the sake of taking into account the user's range of use.

[0024] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A sub-zero time-delay disconnection type leakage protection circuit, wherein a reset button is provided on the live wire and the neutral wire of the power input end of the circuit, a trip coil is connected to the reset button, the input end of the trip coil is also connected to the output end of the solid-state relay, the input end of the solid-state relay is connected to the control electrode of the thyristor SCR1, and the control electrode of the thyristor SCR1 is also connected to the leakage protection module, characterized in that: It also includes a first isolation amplifier and a second isolation amplifier, wherein the reference voltage reference terminal and the input terminal of the first isolation amplifier are respectively connected to a voltage divider resistor and a temperature sensor, the output terminal of the first isolation amplifier is connected to a charging delay circuit and the input terminal of the second isolation amplifier, the charging delay circuit includes a resistor and a timing capacitor, the reference voltage reference terminal of the first isolation amplifier is also connected to a voltage divider resistor, and the output terminal of the second isolation amplifier is connected to the control electrode of the thyristor SCR1.

2. A sub-zero time-delay disconnection type leakage protection circuit according to claim 1, wherein: The timing time of the timing capacitor is not higher than 60 minutes.

3. A sub-zero time-delay disconnection type leakage protection circuit according to claim 1, wherein: The minimum temperature threshold of the temperature sensor is no higher than minus 1 degree Celsius.

4. A sub-zero time-delay disconnection type leakage protection circuit according to claim 1, wherein: The input end of the solid-state relay is also connected to the output end of the first isolation amplifier.

5. A sub-zero time-delay disconnection type leakage protection circuit according to claim 1, wherein: A diode is provided between the output end of the second isolation amplifier and the control electrode of the thyristor SCR1, and the output end of the second isolation amplifier is connected to the anode of the diode.

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