Overvoltage absorber with thermal protection

Abstract

The utility model discloses an overvoltage absorber with thermal protection, which relates to the field of electrical technology, and comprises a main working loop and a protection control loop, the main working loop is reversely connected in parallel with a first silicon controlled rectifier and a second silicon controlled rectifier through a cathode and an anode to form a main loop control switch, and the parallel end is connected with a line L; the other end of the thermal element of the thermal relay is connected with one end of the resistor, and the other end of the resistor is connected with the N. The control loop is connected in series with the anode of the first voltage stabilizing diode through the gate pole of the first silicon controlled rectifier, and the cathode of the first voltage stabilizing diode is connected in series with the cathode of the second voltage stabilizing tube. The anode of the second voltage-regulator tube is connected to one end of a normally-closed contact of the thermal relay, and the other end of the normally-closed contact of the thermal relay is serially connected to the gate pole of the second silicon controlled rectifier. The overvoltage absorber is used for solving the problems that a traditional overvoltage absorber cannot rapidly cut off the power frequency follow current of the action of the absorber, and burning loss and even explosion are caused by continuous heating of an overvoltage absorbing device due to various reasons.

Description

Technical Field

[0001] This utility model relates to the field of electrical technology, specifically to an overvoltage absorber with thermal protection. Background Technology

[0002] In power systems, overvoltage pulses can occur due to grid faults, power switch operations, and lightning strikes. These overvoltage pulses can damage electrical equipment, so suppressing overvoltage pulses is a necessary means of protecting electrical equipment. However, in practical applications, existing overvoltage absorbers often fail to effectively cut off the subsequent normal power frequency follow current after "activation," leading to further deterioration of the overvoltage absorber's heating. This causes changes in the overvoltage absorber's characteristics, further increases the normal power frequency follow current, and ultimately results in the overvoltage absorber burning out or even exploding. Summary of the Invention

[0003] To address the aforementioned technical problems, this utility model provides an overvoltage absorber with thermal protection, which solves the problems of traditional overvoltage absorbers failing to quickly cut off the absorber's "action," the power frequency follow current, and the overvoltage absorption device continuously heating up due to various reasons, leading to burnout or even explosion.

[0004] To achieve the above objectives, the specific technical solution of this utility model is as follows:

[0005] An overvoltage absorber with thermal protection is characterized by comprising a main working circuit and a protection control circuit. The main working circuit forms a main circuit control switch by connecting a first thyristor and a second thyristor in reverse parallel with their anode and cathode. One end of the thyristor is connected to line L, and the other end is connected to one end of the thermal element of a thermal relay. The other end of the thermal element of the thermal relay is connected to one end of a resistor, and the other end of the resistor is connected to N. The control circuit is connected in series between the gates of the first thyristor to the anode of a first Zener diode. The cathode of the first Zener diode is connected in series to the cathode of a second Zener diode. The anode of the second Zener diode is connected to one normally closed point of the thermal relay, and the other normally closed point of the thermal relay is connected in series to the gate of the second thyristor.

[0006] The beneficial effects of this invention are as follows: When the power frequency AC power supply is operating at normal voltage, the first and second thyristors are in the off state, and the overvoltage absorber does not work. When the power system experiences a prolonged overvoltage, the voltage absorber continues to operate, causing the overheating relay's heating element and release resistor to generate significant heat. When the heat reaches the thermal relay's setting value, the normally closed contact of the thermal relay opens, and both anti-parallel thyristors are in the off state, thus solving the problem of not being able to effectively cut off subsequent normal power frequency follow current. When the power frequency AC power supply is operating at normal voltage, the breakdown voltages of the two anti-parallel series Zener diodes are both higher than the normal operating voltage at the L terminal of the protected line. Therefore, no current flows through the aforementioned control branch, and the first and second thyristors are in the off state, and the overvoltage absorber does not work. When a positive overvoltage pulse occurs on the L terminal of the protected line, the second Zener diode in the control branch is reverse-broken down, allowing current to flow. This applies a positive trigger voltage to the gate of the second thyristor, causing forward conduction between the anode and cathode of the second thyristor. The positive high-voltage pulse on the L terminal of the protected line then flows through the second thyristor, the thermal relay element, and the release resistor into the N terminal. When the positive pulse at the L terminal drops below the breakdown voltage of the Zener diode, the second Zener diode is cut off, and the current in the control branch becomes zero. When the voltage at the L terminal is zero, the current flowing between the anode and cathode of the second thyristor is also zero, causing the second thyristor to cut off. This immediately stops the overvoltage absorber from suppressing high voltage. When a reverse overvoltage pulse occurs on the L terminal of the protected line, the working principle is the same, effectively suppressing overvoltage pulses and protecting electrical equipment. When a power system experiences prolonged overvoltage, the overvoltage absorber will continue to operate, causing the overheating relay's heating element and release resistor to generate significant heat. When the heat reaches the relay's setting value, the normally closed contact of the relay will open, disconnecting the energized branch between the gates of the two anti-parallel thyristors. This keeps both thyristors in a cut-off state, preventing the release resistor from burning out. After a period of heat dissipation, the normally closed contact of the relay automatically returns to its normally closed state, and the overvoltage absorber re-enters overvoltage protection mode. This solves the problems of traditional overvoltage absorbers failing to quickly cut off the power frequency follow current and overheating leading to burnout or even explosion of the overvoltage absorption device due to various reasons. Attached Figure Description

[0007] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0008] Figure 1 This is the electrical schematic diagram of this utility model.

[0009] Reference numerals in the attached figures: 1. First thyristor; 2. Second thyristor; 3. First Zener diode; 4. Second Zener diode; 5. Normally closed contact of thermal relay; 6. Thermal element of thermal relay; 7. Release resistor. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this utility model. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of this utility model.

[0011] like Figure 1 As shown, an overvoltage absorber with thermal protection includes a main working circuit and a protection control circuit. The main working circuit forms a main circuit control switch by connecting a first thyristor 1 and a second thyristor 2 in reverse parallel with their anode and cathode. One end of the parallel connection is connected to line L, and the other end is connected to one end of the thermal element 6 of a thermal relay. The other end of the thermal element 6 of the thermal relay is connected to one end of a resistor 7, and the other end of the resistor 7 is connected to N. The gate of the first thyristor 1 is connected in series with the anode of the first Zener diode 3. The cathode of the first Zener diode 3 is connected in series with the cathode of the second Zener diode 4. The anode of the second Zener diode 4 is connected to one end of the normally closed point 5 of the thermal relay. The other end of the normally closed point 5 of the thermal relay is connected in series with the gate of the second thyristor 2.

[0012] When this utility model is in use, when the power frequency AC power supply is operating at normal voltage, the current flows through the L terminal and the cathode of the first thyristor 1 to the gate, then through the first Zener diode 3 and the second Zener diode 4 connected in reverse series, the normally closed contact 5 of the thermal relay, and the gate of the second thyristor 2 to the cathode branch. Since the breakdown voltages of the two reverse-connected Zener diodes are higher than the normal operating voltage on the L terminal of the protected line, no current flows through the above-mentioned control branch. Therefore, the first thyristor 1 and the second thyristor 2 are in the cut-off state, and the overvoltage absorber does not work at this time. When a positive overvoltage pulse appears on the L terminal of the protected line, the second Zener diode 4 in the control branch is reverse-broken down, allowing current to flow. This applies a positive trigger voltage to the gate of the second thyristor 2, causing forward conduction between the anode and cathode of the second thyristor 2. The positive high-voltage pulse on the L terminal of the protected line then flows through the second thyristor 2, the thermal relay element 6, and the release resistor 7 into the N terminal. When the positive pulse at the L terminal drops below the breakdown voltage of the Zener diode, the second Zener diode is cut off, and the current in the control branch becomes zero. When the voltage at the L terminal is zero, the current flowing between the anode and cathode of the second thyristor 2 is also zero, causing the second thyristor 2 to cut off. This immediately stops the overvoltage absorber from suppressing high voltage. When a reverse overvoltage pulse appears on the L terminal of the protected line, the working principle is the same.

[0013] When the power system experiences prolonged overvoltage, the overvoltage absorber will continue to operate, causing the overheating relay's heating element 6 and release resistor 7 to generate significant heat. When the heat reaches the thermal relay's setting value, the normally closed contact 5 of the thermal relay will open, disconnecting the energized branch between the gates of the two anti-parallel thyristors. This will keep both anti-parallel thyristors in the off state, preventing the release resistor 7 from burning out. After a certain period of heat dissipation, the normally closed contact 5 of the thermal relay will automatically return to its normally closed state, and the overvoltage absorber will re-enter the overvoltage protection state.

[0014] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this utility model and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this utility model should be included within its protection scope. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. An overvoltage absorber with thermal protection, characterized in that, The main working circuit includes a main working circuit and a protection control circuit. The main working circuit forms a main circuit control switch by connecting the first thyristor (1) and the second thyristor (2) in reverse parallel with the anode and cathode. One end of the parallel circuit is connected to line L, and the other end is connected to one end of the thermal element (6) of the thermal relay. The other end of the thermal element (6) of the thermal relay is connected to one end of the resistor (7), and the other end of the resistor (7) is connected to N. The protection control circuit is connected to the anode of the first Zener diode (3) in series between the gates of the first thyristor (1). The cathode of the first Zener diode (3) is connected in series to the cathode of the second Zener diode (4). The anode of the second Zener diode (4) is connected to one end of the normally closed point (5) of the thermal relay. The other end of the normally closed point (5) of the thermal relay is connected in series to the gate of the second thyristor.

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