Overvoltage absorber with thermal protection

Abstract

The invention 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] The invention relates to the field of electrical technology, and in particular to an overvoltage absorber with thermal protection. Background Art

[0002] In the power system, due to grid failure, power switch operation and lightning, etc., overvoltage pulses may occur in the grid. Such overvoltage pulses may cause damage to electrical equipment. Therefore, suppressing overvoltage pulses is a necessary means to protect electrical equipment. At the same time, in actual applications, the existing overvoltage absorbers often fail to cut off the subsequent normal power frequency continuous current after the overvoltage absorber "acts", which leads to further deterioration of the heating of the overvoltage absorber, thereby causing changes in the characteristics of the overvoltage absorber, further increase in the normal power frequency continuous current, and ultimately causing the overvoltage absorber to burn out or even explode. Summary of the invention

[0003] In response to the above technical problems, the present invention provides an overvoltage absorber with thermal protection, which is used to solve the problem that the traditional overvoltage absorber cannot quickly cut off the power frequency continuous current of the absorber "action" and the overvoltage absorption device continues to heat up for various reasons, leading to burning or even explosion.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows: An overvoltage absorber with thermal protection is characterized in that it 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 and a second thyristor in reverse parallel through the anode and cathode. One end of the parallel connection is connected to the line L, and the other end is connected to one end of the thermal element of the 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 with the anode of the first zener diode through the gate of the first thyristor, the cathode of the first zener diode is connected in series with the cathode of the second zener tube, the anode of the second zener tube is connected to one end of the normally closed point of the thermal relay, and the other end of the normally closed point of the thermal relay is connected in series with the gate of the second thyristor.

[0005] The beneficial effects of the present invention are as follows: when the industrial frequency AC power supply is working at normal voltage, the first thyristor and the second thyristor are in the cut-off state, and the overvoltage absorber does not work at this time. When the overvoltage lasts for a long time in the power system, the voltage absorber continues to work, causing the overheating relay thermal element and the release resistor to generate high heat. When the heat generation reaches the setting value of the thermal relay, the normally closed contact of the thermal relay is disconnected, and the two reverse parallel thyristors are both in the cut-off state, which solves the problem of not being able to cut off the subsequent normal industrial frequency continuous current. When the industrial frequency AC power supply is working at normal voltage, the forward and reverse working breakdown voltages of the two reverse series zener diodes are higher than the normal working voltage on the L terminal of the protected line, so no current passes through the above control branch, so the first thyristor and the second thyristor are in the cut-off state, and the overvoltage absorber does not work at this time. When a forward overvoltage pulse appears on the L terminal of the protected circuit, the second voltage-stabilizing tube of the control branch is reversely broken down and current passes through it, so that a forward trigger voltage is applied to the gate of the second thyristor, so that the anode and cathode of the second thyristor are forwardly conducted, so that the forward high voltage pulse on the L terminal of the protected circuit flows through the second thyristor, the thermal element of the thermal relay, and the release resistor and flows into the N terminal. When the forward pulse at the L terminal drops below the breakdown voltage of the voltage-stabilizing diode, the second voltage-stabilizing diode is cut off, and the current in the control branch is 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, and the second thyristor is cut off, so that the overvoltage absorber immediately stops suppressing the high voltage. When a reverse overvoltage pulse appears on the L terminal of the protected circuit, the working principle is the same as above, and the overvoltage pulse is effectively suppressed to protect the electrical equipment. When overvoltage occurs continuously in the power system for a long time, the overvoltage absorber will continue to work, causing the overheating relay thermal element and the release resistor to generate high heat. When the heat generation reaches the setting value of the thermal relay, the normally closed contact of the thermal relay will be disconnected, so that the energized branch between the gates of the two reverse-parallel thyristors will be disconnected. This will put the two reverse-parallel thyristors in the cut-off state to avoid burning of the release resistor. After a certain period of heat dissipation, the normally closed contact of the thermal relay will automatically return to the normally closed state, and the overvoltage absorber will re-enter the overvoltage protection state, solving the problem that the traditional overvoltage absorber cannot quickly cut off the power frequency follow-current of the absorber "action" and the overvoltage absorption device continues to heat up for various reasons, leading to burning or even explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention is further described below in conjunction with the accompanying drawings and embodiments: Figure 1 The electrical schematic diagram of the present invention.

[0007] Figure numerals: first thyristor 1, second thyristor 2, first voltage-stabilizing tube 3, second voltage-stabilizing tube 4, normally closed point of thermal relay 5, thermal element of thermal relay 6, release resistor 7. DETAILED DESCRIPTION

[0008] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0009] 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 the first thyristor 1 and the second thyristor 2 in reverse parallel through the anode and cathode. One end of the parallel connection is connected to the 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 anode of the first zener diode 3 is connected in series between the gates of the first thyristor 1, the cathode of the first zener diode 3 is connected in series with the cathode of the second zener tube 4, the anode of the second zener tube 4 is connected to one end of the normally closed point 5 of the thermal relay, and the other end of the normally closed point 5 of the thermal relay is connected in series to the gate of the second thyristor 2.

[0010] When the present invention is in use, when the industrial frequency AC power supply is working at normal voltage, through the L terminal and the cathode to gate of the first thyristor 1, and then through the first voltage regulator 3 and the reversely connected second voltage regulator 4 and the normally closed point 5 of the thermal relay, the gate to cathode branch of the second thyristor 2, since the forward and reverse working breakdown voltages of the two reversely connected voltage regulator diodes are higher than the normal working voltage on the L terminal of the protected circuit, no current passes through the above control branch, so 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 forward overvoltage pulse appears on the L terminal of the protected circuit, the second voltage-stabilizing tube 4 of the control branch is reversely broken down and current passes through, so that a forward trigger voltage is applied to the gate of the second thyristor 2, so that the anode and cathode of the second thyristor 2 are forwardly conductive, so that the forward high voltage pulse on the L terminal of the protected circuit flows through the second thyristor 2, the thermal element 6 of the thermal relay, and the release resistor 7 and flows into the N terminal. When the forward pulse at the L terminal drops below the breakdown voltage of the voltage-stabilizing diode, the second voltage-stabilizing diode is cut off, and the current of the control branch is 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, and the second thyristor 2 is cut off, so that the overvoltage absorber immediately stops the work of suppressing the high voltage. When a reverse overvoltage pulse appears on the L terminal of the protected circuit, the working principle is the same as above.

[0011] When the overvoltage in the power system lasts for a long time, the overvoltage absorber will continue to work, causing the overheating relay thermal element 6 and the release resistor 7 to generate high heat. When the heat generation reaches the setting value of the thermal relay, the normally closed contact 5 of the thermal relay will be disconnected, so that the energized branch between the gates of the two reverse-parallel thyristors will be disconnected. This will put the two reverse-parallel thyristors in the cut-off state, preventing the release resistor 7 from being burned. After a certain period of heat dissipation, the normally closed contact 5 of the thermal relay will automatically return to the normally closed state, and the overvoltage absorber will re-enter the overvoltage protection state.

[0012] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. An overvoltage absorber with thermal protection, characterized in that: The invention comprises 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 anode and cathode. One end of the parallel connection is connected to a line L, and the other end is connected to one end of a 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). The other end of the resistor (7) is connected to N. The protection control circuit connects the anode of a first voltage regulator diode (3) in series between the gates of the first thyristor (1). The cathode of the first voltage regulator diode (3) is connected in series to the cathode of a second voltage regulator tube (4). The anode of the second voltage regulator tube (4) is connected to one end of a 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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