WO2020083179A1

WO2020083179A1 - Arc suppressing circuit and apparatus as well as switch system

Info

Publication number: WO2020083179A1
Application number: PCT/CN2019/112180
Authority: WO
Inventors: 郭桥石
Original assignee: 郭桥石
Priority date: 2018-10-22
Filing date: 2019-10-21
Publication date: 2020-04-30
Also published as: CN112740352B; CN112740352A

Abstract

Disclosed are an arc suppressing circuit and apparatus as well as a switch system, applicable to quick arc suppressing in a multichannel mechanical switch, comprising a capacitance (C1) and first switches (S1). During the breaking process of a mechanical switch (K), the capacitor (C1) supplies power, via a first switch (S1), to a load (RL) for arc suppressing in the mechanical switch. There are two or more than two mechanical switches (K), loads (RL) and first switches (S1), wherein the first switch (S1) is a semiconductor switch. The arc suppressing circuit and apparatus as well as the switch system have the advantages of high capacitance utilization and simple circuit.

Description

Arc extinguishing circuit and device, switch system

Technical field

The invention relates to an arc extinguishing circuit and device, in particular an arc extinguishing circuit and device suitable for quickly extinguishing an arc of a multi-way contactor (relay) and other mechanical switches, and can also be used for other breakpoints (such as fuse-link fusing) , The break point between the plug and the socket, the break point of the wire), and a switching system using the arc extinguishing circuit and device of the present invention.

Background technique

At present, in electronic control systems such as new energy vehicles, rail transit, ships, and automatic control, multi-way (two or more) contactors (relays) and other mechanical switches are commonly used to frequently turn on and off the load. The mechanical switch has a breaking arc, especially direct current, because it has no zero point, the breaking arc is larger, and there is a shortcoming of the short electrical life of the mechanical switch. As the breaking voltage of the mechanical switch increases and the breaking current increases, the electrical life will be large Reduced, there are also arc extinguishing devices connected to the capacitor for arc extinction in the current market, one is the resistance-capacitance absorption circuit used in small current occasions; the other is the parallel capacitor extinction used with high-priced products such as dual power supply switching, medium and high voltage circuit breakers, etc. The former can only be used in small current applications, while the latter has high cost, small application range, poor versatility, and is difficult to popularize.

Summary of the invention

The purpose of the present invention is to solve the problem of short electrical life of mechanical switches in the existing electronic control system, to provide an arc extinguishing circuit and device with high capacitance utilization rate, which can extinguish multi-path mechanical switches, a wide range of applications, and an adoption The mechanical switch has a low cost, small size, extremely low operating cost and a switching system using the arc extinguishing device of the present invention.

The purpose of realizing the present invention is achieved by the following technical solutions:

An arc extinguishing circuit, a mechanical switch required for arc extinguishing is connected to a load, which is composed of a capacitor and a first switch. During the breaking process of the mechanical switch, the capacitor supplies power to the load through the first switch. The number of switches, loads, and first switches is two or more, and the first switches are semiconductor switches.

An arc extinguishing device including the arc extinguishing circuit described above further includes a control unit; the control unit is connected to the capacitor and the mechanical switch.

A switch system including the arc extinguishing device described above, further includes the mechanical switch, and the mechanical switch body does not have a breaking force for the working current of the load.

The invention has reasonable design and has the advantages of high capacitance utilization rate.

BRIEF DESCRIPTION

FIG. 1 is a circuit schematic diagram of an embodiment one of the arc extinguishing circuit, device and switching system of the present invention.

2 is a schematic diagram of the first switching circuit of the arc extinguishing circuit and device and the switching system of the present invention.

FIG. 3 is a circuit schematic diagram of the second embodiment of the arc extinguishing circuit, device and switching system of the present invention.

4 is a schematic diagram of Embodiment 3 of the arc extinguishing device and the switching system of the present invention.

detailed description

The first embodiment of the arc extinguishing circuit, device and switch system of the present invention is shown in Fig. 1:

An arc extinguishing circuit, a mechanical switch K required for arc extinction is connected to a load RL, which is composed of a capacitor C1 and a first switch S1. During the breaking of the mechanical switch K, the capacitor C1 supplies power to the load RL through the first switch S1. The mechanical switch K extinguishes the arc.

The first switch S1: adopt half-control device; or use half-control device in series with an uncontrollable device.

The first switch S1 can also use the circuit shown in FIG. 2 as a voltage change rate detection type switch, including a semi-controlled device SCR1, a second capacitor C2, a first diode D1 (optional), a semi-controlled device SCR1 is connected in series with the diode D1, the voltage of the load RL triggers the semi-controlled device SCR1 to turn on through the second capacitor C2 (or the voltage of the mechanical switch K triggers the semi-controlled device SCR1 to turn on through the second capacitor C2, such as putting the second capacitor C2 The grounding terminal of the switch is connected to the power supply terminal of the mechanical switch K); in order to overcome the current impact of the mechanical switch K closing, it also includes a second diode D2, a second resistor R2, a second diode D2, a second resistor R2 A parallel circuit is formed, and the parallel circuit is connected in series with the second capacitor C2. The first switch S1 uses a voltage change rate detection type switch, and is particularly suitable for use in occasions with large voltage fluctuations or large ripples, such as battery-powered systems such as electric vehicles or AC rectified power supply systems.

An arc extinguishing device includes the arc extinguishing circuit described above, and further includes a control unit A; the control unit A is connected to the capacitor C1, the mechanical switch K, and the first switch S1, and the control signal of the first switch S1 is controlled by the control unit A provide. Note: When the first switch S1 uses the circuit shown in FIG. 2, the control unit A does not need to provide a signal to the first switch S1.

Working principle: The control unit A charges the capacitor C1. During the breaking process of the mechanical switch K, the first switch S1 is turned on, and the capacitor C1 supplies power to the load RL through the first switch S1. The voltage across the load RL increases rapidly, and the mechanical switch K The potential difference at the terminal drops rapidly (or the reverse voltage present at both ends of the mechanical switch K) to achieve the purpose of the mechanical switch K extinguishing (single current pulse can achieve reliable arc extinction).

This embodiment has the advantages of high capacity utilization and high reliability.

The second embodiment of the arc extinguishing circuit, device and switch system of the present invention is shown in FIG. 3:

An arc extinguishing circuit, the mechanical switch K required for arc extinction is connected to the load RL, which is composed of a capacitor C1, a first switch S1, and a second switch S2 (optional). During the breaking process of the mechanical switch K, the capacitor C1 passes the The second switch S2 and the first switch S1 supply power to the load RL and are used for the mechanical switch K to extinguish the arc.

The first switch S1: the semi-controlled device SCR1 and the uncontrollable device D1 (diode) are connected in series. When designing and selecting, the unreliable device D1 has better working reliability than the semi-controlled device SCR1; or the semi-controlled device alone Type device SCR1;

The first switch S1 may also use the circuit shown in FIG. 2.

An arc extinguishing device includes the arc extinguishing circuit described above, and further includes a control unit A; the control unit A is connected to the capacitor C1, the mechanical switch K, and the first switch S1, and the control signal of the first switch S1 is controlled by the control unit A provide.

Also includes a second switch S2 (semiconductor switch, which is a diode, or a half-controlled device, the control signal of the half-controlled device is provided by the control unit A), the capacitor C1 and the second switch S2 form a first series circuit, the first The voltage signal of the common terminal PC connected between the series circuit and the first switch S1 is connected to the control unit A (used to detect the working state of the first switch, such as on, off, and breakdown), and also includes a first resistor R1 (when the second When the switch S2 is a semi-controlled device, it can be omitted), the power supply (provided by the power supply connected by the mechanical switch K) is connected to the common terminal PC through the first resistor R1 (the first resistor R1 can also be connected in series with a photocoupler to detect the common terminal Voltage).

When the arc extinguishing voltage provided by the capacitor C1 is higher than the working voltage of the load RL, the mechanical switch K is connected in series with a unidirectional conducting device S3 (third switch, diode), which can overcome the problem that the current of the capacitor C1 is poured through the mechanical switch K and improve the capacitance The utilization rate of C1, when the current is large, the unidirectional conduction device S3 can be connected in parallel with a bypass switch PT, the control signal of the bypass switch PT is provided by the control unit A, the bypass switch PT body under the working current condition, the voltage breaking force Less than 50 volts.

Working principle: The control unit A charges the capacitor C1. During the breaking process of the mechanical switch K, the first switch S1 is turned on, and the capacitor C1 supplies power to the load RL through the first switch S1. The voltage across the load RL increases rapidly, and the mechanical switch K The potential difference at the terminal drops rapidly (or the reverse voltage at both ends of the mechanical switch K) to achieve the purpose of the arc extinguishment of the mechanical switch K; if during the arc extinguishment, the first switch S1 breaks down, the PC terminal appears low for a long time If the PC terminal changes from low level to high level during the arc extinguishing process, the first switch S1 is cut off and the arc extinguishing is completed.

In the above embodiment, the voltage signal of the capacitor C1 (used to detect the working state of the first switch S1, the on, off, and breakdown of the first switch S1 can also be used to detect the capacity of the capacitor C1, or a current sensor can be used to detect the capacitor C1 current signal, the current signal is passed to the control unit A) to the control unit A, the control unit A is used to charge the capacitor C1, discharge the capacitor C1, in order to improve the response speed, the control unit A uses a semiconductor switch to charge the capacitor C1 and Discharge; the voltage signal of the common terminal of the mechanical switch K and the load RL is transferred to the control unit A (the voltage across the load RL, or the voltage across the mechanical switch K, or the voltage of the common terminal relative to the capacitor C1), the input of the mechanical switch K The voltage signal of the terminal power supply is connected to the control unit A.

The control signal of the mechanical switch K (not limited to provided by the control end of the mechanical switch K, but also provided by the J2 port) is transmitted to the control unit A, or the control signal of the mechanical switch K is provided by the control unit A, or the mechanical switch K is used The auxiliary switch signal is transmitted to the control unit A, which can also be used in combination with any of the previous (convenient detection of arc reignition), which is helpful to improve the accuracy and real-time of arc extinguishment, and is more conducive to the action logic and Arc control logic for optimal control, selected according to needs;

Control unit A: Built-in a programmable device (such as a microcontroller), an intelligent unit with built-in control program in control unit A, without increasing hardware resources or adding very few hardware resources Different conditions (capacitive, inductive, resistive, current) adjust the control method to improve the arc extinguishing effect, effectively improve the electrical life of the multi-path mechanical switch K, and can complete timing (delay control of the first switch S1 conduction), voltage Acquisition, voltage comparison (such as the voltage across the mechanical switch), logic processing, controlling the charging and discharging of capacitor C1, adjusting the charging voltage of capacitor C1, etc., are helpful to simplify the circuit; shared capacitor C1, control unit A to multiple mechanical switches K ( Mechanical switches can be connected in series or parallel to each other) for arc extinguishing control, mechanical switch K closing arc extinguishing (or load RL pre-charging) and detection (closed state, open state, arcing, and whether each state is stable and normal), according to The arcing situation and the number of operations of the mechanical switch K calculate the life of the mechanical switch K, and transmit or display relevant information (fault code, number of mechanical switch operations, electrical life, Mechanical life, working status, etc.), which is conducive to improving the overall safety of the electronic control system, easy to maintain, and has a higher cost performance. It can be widely used in various electronic control fields. Multi-channel mechanical switch intelligent management system for switch life calculation and end-of-life prediction, mechanical switch working state detection.

Since the electrical characteristics of the multiple mechanical switches K and the multiple loads RL connected to the control unit A may not be consistent, in order to achieve the best arc extinguishing effect, the control unit A stores the parameters related to the current of the load RL, or inputs the current related to the load RL Related parameters or signals, or the operating time parameters of the mechanical switch K, the charging voltage of the capacitor C1 is proportional to the current through the mechanical switch K that needs to be extinguished (using the control unit A to adjust the charging voltage of the capacitor C1), mechanical During the switch K breaking operation, the delay time of the first switch S1 is proportional to the current of the load RL. The delay time parameter can be completed by the programmable device built in the control unit A; it is helpful to overcome the arc extinction process The impact of overvoltage on the system and achieve the best arc extinguishing effect.

The control unit A is used to record the number of operations of the mechanical switch, and the control unit A is used to detect (by detecting the corresponding voltage, or the auxiliary switch of the mechanical switch, or the load current) the contact of the mechanical switch K is opened.

The control unit A may include a display unit, or a display unit (which may be connected by a communication port) is used to display the operating state of the mechanical switch K, the number of operations of the mechanical switch K, the arc extinguishing operating state, and the remaining life of the mechanical switch K (mechanical life, Information such as electrical life); the control unit A may include an input unit (keys, etc.), or an input unit (which may be connected using a communication port) is connected.

J1 can be connected to an external power port (optional); J2 is a communication port for transmitting and receiving related information.

The third embodiment of the arc extinguishing device and the switch system of the present invention is shown in FIG. 4:

The arc extinguishing device mentioned above is placed in a shell. As a versatile product, it is connected to external mechanical switches and host computers through terminals to facilitate safety certification and popularization. Its specific shape can be flexibly designed according to needs. .

A switching system:

The switch system including the arc extinguishing device described above (Example 1, shown in Figure 1; Example 2, shown in Figure 3; Example 3, shown in Figure 4), also includes a mechanical switch K, mechanical The switch K body does not have the breaking current breaking force to the load RL (means that the mechanical switch does not have the breaking current breaking load to the load RL without the capacitor C1 supplying power to the load RL).

The mechanical switch K required for the arc extinguishing of the switching system of the present invention can be a mechanical switch (relay, contactor, travel switch, etc.) that does not have a breaking force (voltage, current breaking force) under the working conditions, which greatly reduces the cost 1. The purpose of reducing weight and volume of mechanical switch.

The above first switch S1 is a semiconductor switch (unidirectional conduction switch) and is a controllable switch, preferably a semi-controlled device (semi-controlled switch), and the semi-controlled device is preferably a unidirectional thyristor.

In the above embodiment, the first switch S1 is a unidirectional conduction switch, a controllable semiconductor switch, and is a half-controlled device. Each first switch S1 is connected in reverse series. To improve the withstand voltage level, the first switch S1 can be connected in series One or more diodes have the advantages of low cost and strong overload capacity. Capacitor C1 can be connected in series with current limiting components as needed.

The common end of each mechanical switch K and the load RL is connected through a first switch (semiconductor device, unidirectional thyristor), and the common end between the capacitor C1 and each first switch S1 is connected.

When the first switch uses a fully controlled device (such as a triode, field effect transistor, IGBT, etc.), the fully controlled device has at least one diode in series.

In the above embodiment, the capacitor C1 can be connected in series with an inductor current limit (which can be omitted when the capacitor C1 has a large internal resistance to the load RL working line), which is used to increase the supply time of the capacitor C1 to the load RL and reduce the current rise rate; series inductance Selection of parameters: Under actual working conditions, the device makes the current rise rate through the first switch S1 less than the limit rise rate of the first switch S1; in order to achieve the best efficiency and safety, a pair of wires can be used on site Short-circuit the two ends of the load RL; or use a capacitor (or other capacitive or resistive load) to connect the two ends of the load RL in parallel; the capacitor C1 is charged, and then the first switch S1 is turned on, the system voltage and the voltage of the capacitor C1 are superimposed, so that The rate of current rise through the first switch S1 is less than the limit rate of rise of the first switch S1 (first device SCR1, second device SCR2).

At the same time, the mechanical switch without breaking force has a slower breaking and closing speed of the mechanical contacts, less mechanical impact, and a higher operating electrical life compared to the mechanical switch with breaking force. When the mechanical switch is in motion and may appear Under the condition of unexpected mechanical shock (such as collision, rollover, etc.), the mechanical switch K may be accidentally closed and broken under the normally open state, or the opening distance becomes smaller, or the surge voltage appears at both ends of the mechanical switch K. Arc, when the control unit A detects the ignition arc in the state of the mechanical switch K is disconnected (detecting the voltage at the common terminal of the mechanical switch K and the load RL can be known), the control unit A controls the first switch S1 to conduct to extinguish the arc.

In the above embodiment, under the condition that the control unit A detects that the arc extinguishment has failed (the control unit A knows from the voltage or current of the capacitor C1; the control unit A charges the capacitor C1 again, and then performs the second arc extinguishment, it can be Greatly improve the reliability of arc extinction and the response speed of secondary arc extinction.

In the above embodiments, the number of the mechanical switch K, the load RL, and the first switch S1 is two or more, and the common capacitor C1 and the control unit A (share a programmable device) can achieve significant cost savings and volume reduction. In order to effectively overcome the line loss caused by the layout of the multi-mechanical switch K and the capacitor C1 is too long relative to the load RL arc extinction circuit line, provide sufficient arc extinction current and improve the arc extinction effect, the capacitor C1 provides the extinction of the load RL The arc voltage is higher than the operating voltage of the load RL (such as the PB terminal is grounded, the charging voltage of the capacitor C1 is greater than the operating voltage of the load RL; if the PB terminal is connected to a voltage, the capacitor C1 can also be reversely charged, and then the voltage passes through a semiconductor The voltage of the switch and capacitor C1 is superimposed to supply power to the load RL. This voltage can be provided by another capacitor or a power supply connected by a mechanical switch K; the voltage provided by the capacitor C1 can also be the voltage of the external power source coupled to the load RL through the capacitor C1; As shown in FIG. 1, the PB terminal of the capacitor C1 as shown in FIG. 2 can be connected to the power ground or a power source according to needs).

The limit of the effective value of the arc extinguishing current by the capacitor is used to prevent the risk of the first switch S1 breaking down to supply power to other loop loads RL; The switches S1 are connected, and the first switch S1 of each channel is connected in reverse series. There is no problem that the mechanical switch K caused by false conduction supplies power to the load RL connected to the other mechanical switch K, and each mechanical switch K is provided. The high voltage resistance between the output terminals (easy to reach 4000 volts when the first switch S1 uses a unidirectional thyristor), fast response speed, small size, low cost, and no limitation of the life limit of the number of arc extinguishing operations; To further improve safety when the system voltage is high, the first switch S1 can use a semi-controlled device (such as a unidirectional thyristor, its conventional model withstand voltage can reach 1500 to 2000 volts, using a unidirectional thyristor with a rated current of 25 amps, It can extinguish the mechanical switch of thousands of amperes of current, and the arc extinguishing pulse current can be controlled between tens of microseconds and 1 millisecond. One or more diodes are connected in series (uncontrollable devices, the conventional voltage resistance of the diodes can be It is composed of up to 1000 to 2000 volts, using a rated current of 10 ampere diodes, which can extinguish the arc of mechanical switches with thousands of amperes of current), which can greatly improve the insulation withstand voltage between the output terminals of various mechanical switches (easy to reach 6000 volts) , Or more than ten thousand volts), has the advantages of low cost, high withstand voltage capability, strong overcurrent capability, and high reliability.

The arc extinguishing device of the present invention is not only an intelligent electronic arc extinguishing system with increased electrical life of mechanical switches, but also a multi-path mechanical switch management system (multi-path mechanical switch arc management system), and without increasing hardware resources It can be used as a multi-channel mechanical switch intelligent management system for mechanical switch life calculation and end-of-life prediction, mechanical switch operation frequency recording, and mechanical switch working state detection. It can also greatly reduce the manual maintenance cost and operating cost of the system (electric control system). Improve the safety of system operation and the level of intelligence of the equipment, without the need for bulky and expensive high-breaking mechanical switches (change the original electrical design standard), reduce environmental pollution caused by frequent replacement of switches, and have high economic value And social value, it is extremely conducive to changing the current situation that the electronic arc extinguishment is difficult to popularize.

The switching system of the arc extinguishing device of the present invention not only combines the advantages of the arc extinguishing device of the present invention, but the mechanical switch body does not have a breaking force to the load current, which breaks through the design specifications of the traditional switching system. The mechanical switch of the switching system of the present invention Traditional mechanical switch (with breaking force) has a smaller contact opening distance and slower breaking speed (reducing drive power consumption and mechanical impact on the switch itself), without the need for arc extinguishing grid, vacuum or gas arc extinguishing measures, mechanical switch It has the advantages of low cost, small closing bounce, large connecting current, low power consumption, longer mechanical life, low working noise and small size.

In the above embodiment, the capacity of the capacitor C1 is preferably such that the on-time of the first switch S1 is not greater than 1 millisecond (200 microseconds is preferred. It is recommended that when the contact of the mechanical switch K has a certain opening distance, The penetration voltage is greater than the working voltage of the mechanical switch K, the first switch S1 is turned on, as long as the load has a pulse current of tens of microseconds to achieve a satisfactory arc extinguishing effect), the arc extinguishing device of the present invention can easily meet more than one hundred times Arc extinguishing frequency per second; the control unit A uses a transformer to drive the first switch S1.

In the above embodiment, the operational reliability of the second switch S2 is better than that of the first switch S1.

Note: The embodiment of the present invention is DC arc extinguishing (for systems below 2000V; or systems under 1000V), it can also be used for AC arc extinguishing (synchronous arc extinguishing), and related components can be added for AC arc extinguishing as needed, or Two-way DC arc extinguishing.

In summary, the above embodiments of the present invention have the following advantages:

1. The common end of each mechanical switch connected to the load is connected through a semiconductor device (first switch S1), the capacitor utilization rate is high, the cost is greatly saved, the volume is reduced, and the response speed of the arc extinction is improved.

2. The use of capacitors to facilitate energy storage boosting can provide electrical pulses greater than the input power supply voltage of the mechanical switch to the load. It can also output a large extinction under the conditions of long arc extinction circuit, small wire diameter and large internal resistance. Arc current (1 square wire can transmit hundreds to thousands of amperes).

3. The use of capacitance makes the arc extinguishing energy known, which effectively prevents the damage of the first switch and affects the load of other circuits.

Claims

An arc extinguishing circuit, a mechanical switch required for extinguishing an arc is connected to a load, and is characterized in that it is composed of a capacitor and a first switch. During the breaking process of the mechanical switch, the capacitor passes through the first switch. The load power supply is used to extinguish the arc of the mechanical switch. The number of the mechanical switch, the load, and the first switch is two or more, and the first switch is a semiconductor switch.
The arc extinguishing circuit according to claim 1, characterized in that: a common end of each mechanical switch connected to the load is connected through the first switch, and between the capacitor and each of the first switches Connected to the common end.
The arc extinguishing circuit according to claim 1, wherein the first switch is a unidirectional conduction switch, a semi-controlled switch, and each of the first switches is connected in reverse series.
The arc extinguishing circuit according to claim 1, wherein the first switch is a half-controlled device; or the half-controlled device is connected in series with an uncontrollable device.
The arc extinguishing circuit according to claim 1, characterized in that: the voltage provided by the capacitor is greater than the operating voltage of the load, and the common end of each path of the mechanical switch and the load is connected through a semiconductor device.
The arc extinguishing circuit according to claim 1, wherein the first switch includes a half-controlled device, a second capacitor, and a first diode, the half-controlled device is connected in series with the diode, the The voltage of the load or the voltage of the mechanical switch triggers the conduction of the first switch through the second capacitor.
The arc extinguishing circuit according to claim 6, further comprising a second diode and a second resistor, the second diode and the second resistor form a parallel circuit, and the parallel circuit and the The second capacitor is connected in series.
An arc extinguishing device including the arc extinguishing circuit according to any one of claims 1 to 7, further comprising a control unit; the control unit is connected to the capacitor and the mechanical switch.
The arc extinguishing device according to claim 8, wherein the control signal of the first switch is provided by the control unit.
The arc extinguishing device according to claim 8, wherein the control signal of the mechanical switch is transmitted to the control unit, or the control unit provides the control signal of the mechanical switch, or the auxiliary of the mechanical switch The switch signal is transferred to the control unit.
The arc extinguishing device according to claim 8, wherein the mechanical switch is connected with a unidirectional conducting device in series.
The arc extinguishing device according to claim 8, wherein the voltage signal or the current signal of the capacitor is transmitted to the control unit, and the control unit is used to charge or discharge, or charge and discharge the capacitor.
The arc extinguishing device according to claim 12, wherein the control unit adjusts the charging voltage of the capacitor according to the current through the mechanical switch.
The arc extinguishing device according to claim 8, wherein the voltage signal of the power supply at the input end of the mechanical switch is connected to the control unit.
The arc extinguishing device according to claim 8, wherein the voltage signal at the common terminal of the mechanical switch and the load is transmitted to the control unit.
The arc extinguishing device according to claim 8, further comprising a second switch, the capacitor and the second switch form a first series circuit, and the first series circuit is connected to the first switch The voltage signal at the common terminal is connected to the control unit, and the second switch is a semiconductor switch.
The arc extinguishing device according to claim 16, wherein the second switch is a diode and further includes a first resistor, and the power supply is connected to the common terminal through the first resistor.
The arc extinguishing device according to claim 8, characterized in that it is placed in a housing and connected to the mechanical switch through a terminal.
A switch system including the arc extinguishing device of claim 8, further comprising the mechanical switch, the mechanical switch body does not have a breaking force to the load working current.