CN112740352B

CN112740352B - Arc extinguishing circuit, arc extinguishing device and switch system

Info

Publication number: CN112740352B
Application number: CN201980058376.9A
Authority: CN
Inventors: 郭桥石
Original assignee: Guangzhou Kingser Electronics Co ltd
Current assignee: Guangzhou Kingser Electronics Co ltd
Priority date: 2018-10-22
Filing date: 2019-10-21
Publication date: 2023-06-16
Anticipated expiration: 2039-10-21
Also published as: WO2020083179A1; CN112740352A

Abstract

An arc extinguishing circuit, a device and a switching system are suitable for rapidly extinguishing arc of a plurality of paths of mechanical switches, the arc extinguishing circuit comprises a capacitor (C1) and a first switch (S1), the capacitor (C1) supplies power for a load (RL) through the first switch (S1) in the breaking process of the mechanical switch (K), the arc extinguishing circuit is used for extinguishing arc of the mechanical switch (K), the number of the mechanical switch (K), the load (RL) and the number of the first switch (S1) are two or more, the first switch (S1) is a semiconductor switch, and the arc extinguishing circuit, the device and the switching system have the advantages of high capacitor utilization rate and simple circuit.

Description

Arc extinguishing circuit, arc extinguishing device and switch system

Technical Field

The invention relates to an arc-extinguishing circuit and a device, in particular to an arc-extinguishing circuit and a device which are suitable for rapidly extinguishing arc of mechanical switches such as a multi-path contactor (relay), and can also be used for extinguishing arc of other breakpoints (such as fusing of a fuse link, breakpoints between a plug and a socket and breakpoints of a wire), and a switch system adopting the arc-extinguishing circuit and the device.

Background

At present, in electric control systems such as new energy automobiles, rail transit, ships and automatic control, mechanical switches such as multi-path (two or more) contactors (relays) are commonly used for frequently switching on and switching off the load, and as the mechanical switches have breaking electric arcs, particularly direct current, the mechanical switches have no zero point, the breaking electric arcs are larger, the defects of short electric life of the mechanical switches exist, and as the breaking voltage of the mechanical switches is increased and the breaking current is increased, the electric life of the mechanical switches is greatly reduced, and arc extinguishing devices for connecting capacitors for arc extinction are also present in the market, so that the mechanical switches are resistance-capacitance absorption circuits used in low-current occasions; an arc extinguishing device for arc extinction by parallel capacitor, which is used in combination with high-price products such as dual-power switching and medium-high voltage circuit breaker, has the advantages of high cost, small application range, poor universality and difficult popularization.

Disclosure of Invention

The invention aims to solve the problem of short electrical life of a mechanical switch in the existing electric control system, and provides an arc extinguishing circuit and device which have high capacitance utilization rate and wide application range and are capable of extinguishing arc of a multi-path mechanical switch, and a switching system which adopts the mechanical switch and has the advantages of low cost, small volume, extremely low operation cost and adoption of the arc extinguishing device.

The aim of the invention is achieved by the following technical scheme:

the utility model provides an arc extinguishing circuit, the mechanical switch that needs the arc extinction is connected with the load, and it comprises a electric capacity, first switch, and in the mechanical switch breaking process, electric capacity is the load power supply through first switch for mechanical switch arc extinction, and mechanical switch, load, first switch quantity are two or more, and first switch is the semiconductor switch.

An arc extinguishing device comprising the arc extinguishing circuit, and a control unit; the control unit is connected with the capacitor and the mechanical switch.

A switching system comprising the arc extinguishing device described above, further comprising the mechanical switch, the mechanical switch not having a breaking force on the load operating current.

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

Drawings

Fig. 1 is a schematic circuit diagram of an embodiment of an arc suppressing circuit, an arc suppressing device, and a switching system according to the present invention.

Fig. 2 is a schematic diagram of a first switching circuit of the inventive arc suppressing circuit, apparatus and switching system.

Fig. 3 is a schematic diagram of an arc suppressing circuit, an arc suppressing device, and a switching system according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of an embodiment of an arc extinguishing device and a switching system according to the present invention.

Detailed Description

In a first embodiment of the arc extinguishing circuit, the arc extinguishing device and the switching system of the present invention, as shown in fig. 1:

the utility model provides an arc extinguishing circuit, required arc extinguishing' S mechanical switch K is connected with load RL, and it comprises electric capacity C1, first switch S1, and mechanical switch K divides disconnected in-process, and electric capacity C1 is for load RL power supply through first switch S1 for mechanical switch K arc extinguishing.

First switch S1: a half-control device is adopted; or a half-controlled device is connected in series with an uncontrollable device.

The first switch S1 may also be a circuit as shown in fig. 2, and is a voltage change rate detection switch, including a half-controlled device SCR1, a second capacitor C2, and a first diode D1 (optional), where the half-controlled device SCR1 is connected in series with the diode D1, and the voltage of the load RL triggers the half-controlled device SCR1 to be turned on through the second capacitor C2 (or the voltage of the mechanical switch K triggers the half-controlled device SCR1 to be turned on through the second capacitor C2, for example, the ground terminal of the second capacitor C2 is changed to be connected with the power supply terminal of the mechanical switch K); in order to overcome the current impact of closing the mechanical switch K, the circuit further comprises a second diode D2 and a second resistor R2, wherein the second diode D2 and the second resistor R2 form a parallel circuit, and the parallel circuit is connected with the second capacitor C2 in series. The first switch S1 is a voltage change rate detection switch, and is particularly suitable for occasions with large voltage fluctuation or large ripple, such as a battery power supply system of an electric automobile or the like or an ac rectifying power supply system.

An arc extinguishing device comprises the arc extinguishing circuit and a control unit A; the control unit A is connected with the capacitor C1, the mechanical switch K and the first switch S1, and a control signal of the first switch S1 is provided by the control unit A. And (3) injection: when the first switch S1 adopts 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, the first switch S1 is conducted in the breaking process of the mechanical switch K, the capacitor C1 supplies power to the load RL through the first switch S1, the voltage at two ends of the load RL is rapidly increased, the potential difference at two ends of the mechanical switch K is rapidly decreased (or the reverse voltage is presented at two ends of the mechanical switch K), and the aim of arc extinction of the mechanical switch K is achieved (reliable arc extinction can be achieved through single current pulse).

The embodiment has the advantages of high capacitance utilization rate and high reliability.

In a second embodiment of the arc extinguishing circuit, the arc extinguishing device and the switching system of the present invention, as shown in fig. 3:

the utility model provides an arc extinguishing circuit, required arc extinguishing' S mechanical switch K is connected with load RL, and it comprises electric capacity C1, first switch S1, second switch S2 (optional), and mechanical switch K divides disconnected in-process, and electric capacity C1 is through second switch S2, first switch S1 for load RL power supply for mechanical switch K is in the arc extinguishing.

First switch S1: the semi-controllable device SCR1 and the uncontrollable device D1 (diode) are connected in series, and the working reliability of the uncontrollable device D1 is superior to that of the semi-controllable device SCR1 when the model selection is designed; or a semi-controlled device SCR1 is adopted independently;

the first switch S1 may also employ a circuit as shown in fig. 2.

An arc extinguishing device comprises the arc extinguishing circuit and a control unit A; the control unit A is connected with the capacitor C1, the mechanical switch K and the first switch S1, and a control signal of the first switch S1 is provided by the control unit A.

The semiconductor switch is a diode or a half-controlled device is adopted, a control signal of the half-controlled device is provided by the control unit A, a first series circuit is formed by the capacitor C1 and the second switch S2, a voltage signal of a common terminal PC connected with the first switch S1 in the first series circuit is connected to the control unit A (used for detecting the working state of the first switch, such as on, off and breakdown), the semiconductor switch also comprises a first resistor R1 (which can be omitted when the second switch S2 adopts the half-controlled device), and a power supply (provided by a power supply connected with the mechanical switch K) is connected with the common terminal PC through the first resistor R1 (the first resistor R1 can also be connected with a photoelectric coupler in series to detect the voltage of the common terminal).

When the arc extinction voltage provided by the capacitor C1 is higher than the working voltage of the load RL, the mechanical switch K is connected with a unidirectional conduction device S3 (a third switch and a diode) in series, so that the problem that the current of the capacitor C1 flows backward through the mechanical switch K can be solved, the utilization rate of the capacitor C1 is improved, when the current is large, the unidirectional conduction device S3 can be connected with a bypass switch PT in parallel, a control signal of the bypass switch PT is provided by a control unit A, and the voltage breaking force of the bypass switch PT is smaller than 50 volts under the working current condition.

Working principle: the control unit A charges the capacitor C1, the first switch S1 is conducted in the breaking process of the mechanical switch K, the capacitor C1 supplies power to the load RL through the first switch S1, the voltage at two ends of the load RL is rapidly increased, the potential difference at two ends of the mechanical switch K is rapidly reduced (or the opposite voltage is presented at two ends of the mechanical switch K), and the aim of arc extinction of the mechanical switch K is fulfilled; if breakdown occurs in the first switch S1 during arc extinction, the PC end is low level for a long time; if the PC side is switched from low level to high level during arc extinction, the first switch S1 is turned off, and arc extinction is completed.

In the above embodiment, the voltage signal of the capacitor C1 (used for detecting the working state of the first switch S1, the on/off state and breakdown state of the first switch S1, or may be used for detecting the capacity of the capacitor C1, or may be a current sensor for detecting the current signal of the capacitor C1, where the current signal is transmitted to the control unit a) and transmitted to the control unit a, the control unit a is used for charging the capacitor C1 and discharging the capacitor C1, and in order to increase the response speed, the control unit a uses the semiconductor switch to charge and discharge the capacitor C1; the voltage signal of the common terminal of the mechanical switch K and the load RL is transmitted to the control unit a (the voltage of the two ends of the load RL, or the voltage of the two ends of the mechanical switch K, or the voltage of the common terminal relative to the capacitor C1), and the power voltage signal of the input terminal of the mechanical switch K is connected to the control unit a.

The control signal of the mechanical switch K (not limited to be 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 an auxiliary switch signal of the mechanical switch K is transmitted to the control unit A, and the auxiliary switch signal of the mechanical switch K can be used in combination with any one of the above (convenient for detecting arc reburning), so that the arc extinguishing accuracy and instantaneity are improved, the action logic and the arc extinguishing control logic of each mechanical switch are optimally controlled, and the auxiliary switch signal is selected according to requirements;

control unit a: a programmable device (such as a microcontroller) is built in, an intelligent unit for controlling a program is built in the control unit A, and under the condition of not increasing hardware resources or increasing very few hardware resources, the control mode of adjusting the multipath load RL according to different conditions (capacitive, inductive, resistive and current) of each multipath load RL is realized, the arc extinguishing effect is improved, the electric life of the multipath mechanical switch K is effectively prolonged, the timing (the conduction of the first switch S1 is controlled by delay), the voltage acquisition, the voltage comparison (such as the voltage at two ends of the mechanical switch), the logic processing, the charge and discharge of the capacitor C1 are controlled, the charge voltage of the capacitor C1 is adjusted, and the like, so that the circuit is facilitated to be simplified; the common capacitor C1 and the control unit A perform arc extinction control on the multi-path mechanical switch K (the mechanical switches can be in serial connection or parallel connection), perform arc extinction (or load RL precharge) and detection (the closing state, the opening state and arcing state are stable and normal) on the mechanical switch K, calculate the service life of the mechanical switch K according to the arcing condition and the operation times of the mechanical switch K, and transmit or display related information (fault codes, the operation times of the mechanical switch, the electric service life, the mechanical service life, the working state and the like), thereby being beneficial to improving the overall safety of an electric control system, facilitating maintenance, having the characteristic of higher cost performance, being widely applied to various electric control fields and being used as an intelligent multi-path mechanical switch management system with the functions of increasing the electric service life of the mechanical switch, calculating the service life of the mechanical switch and forecasting the service life of the service life and detecting the working state of the mechanical switch.

Because the electrical characteristics of the multi-path mechanical switch K and the multi-path load RL connected with the control unit A are not necessarily consistent, in order to achieve the optimal arc extinguishing effect, the control unit A stores parameters related to the current of the load RL, or inputs parameters or signals related to the current of the load RL, or action time parameters of the mechanical switch K, the charging voltage of the capacitor C1 is in direct proportion to the current passing through the mechanical switch K requiring arc extinguishing (the charging voltage of the capacitor C1 is adjusted by the control unit A), in the breaking working process of the mechanical switch K, the time of delayed conduction of the first switch S1 is in direct proportion to the current of the load RL, and the time parameter of the delay can be completed by a programmable device arranged in the control unit A; the method is beneficial to overcoming the influence of overvoltage on a system in the arc extinguishing process and achieving the optimal arc extinguishing effect.

The control unit a is used for recording the operation times of the mechanical switch, and the control unit a is used for detecting (by detecting the corresponding voltage, or an auxiliary switch of the mechanical switch, or a load current) the contact opening of the mechanical switch K.

The control unit A can comprise a display unit or be connected with the display unit (can be connected by a communication port) and is used for displaying information such as the action state of the mechanical switch K, the operation times of the mechanical switch K, the arc extinguishing action state, the residual service life (mechanical service life and electric service life) of the mechanical switch K and the like; the control unit a may comprise an input unit (keys etc.) or be connected with an input unit (a communication port connection may be used).

J1 can be externally connected with a power port (optional); j2 is a communication port for transmitting and receiving related information.

In a third embodiment of the arc extinguishing device and the switching system according to the present invention, as shown in fig. 4:

the arc extinguishing device is placed in a shell and used as a product with strong universality, and is connected with external mechanical switches, an upper computer and the like through terminals, so that the arc extinguishing device is convenient and safe to authenticate, is popularized and used, and the specific appearance of the arc extinguishing device can be flexibly designed according to requirements.

A switching system:

the switching system (first embodiment, second embodiment, third embodiment, and third embodiment) including the arc extinguishing device described above (first embodiment, second embodiment, third embodiment, and third embodiment, respectively, is shown in fig. 1, fig. 4) further includes a mechanical switch K, where the mechanical switch K does not have a breaking force on the working current of the load RL (i.e., where the mechanical switch does not have a breaking force on the working current of the load RL without supplying power to the load RL by the capacitor C1).

The mechanical switch K for arc extinction required by the switch system can adopt a mechanical switch (a relay, a contactor, a travel switch and the like) which does not have breaking force (voltage and current breaking force) under the working condition, thereby achieving the purposes of greatly reducing the cost, reducing the weight and reducing the volume of the mechanical switch.

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

In the above embodiment, the first switches S1 are unidirectional conduction switches, are controllable semiconductor switches, are half-controlled devices, and are reversely connected in series, so that in order to improve the voltage-withstanding level, the first switches S1 can be connected in series with one or more diodes, and the capacitor C1 has the advantages of low cost and strong overload capability, and can be connected in series with a current-limiting element as required.

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

When the first switch adopts a fully-controlled device (such as triode, field effect transistor, IGBT, etc.), the fully-controlled device is connected with at least one diode in series.

In the above embodiment, the capacitor C1 may be connected in series with an inductor current limiter (which may be omitted when the internal resistance of the capacitor C1 to the working line of the load RL is larger), so as to increase the power supply time of the capacitor C1 to the load RL and reduce the rising rate of the current; and (3) selecting series inductance parameters: under the actual working condition, the current rising rate of the device passing through the first switch S1 is smaller than the limit rising rate of the first switch S1; in order to achieve the best efficiency and safety, a lead can be utilized to short-circuit the two ends of the load RL on site; or a capacitor (or other capacitive or resistive load) is utilized 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, and the system voltage is superimposed with the voltage of the capacitor C1, so that the current rising rate through the first switch S1 is smaller than the limit rising rate of the first switch S1 (the first device SCR1, the second device SCR 2).

Meanwhile, compared with a mechanical switch with breaking force, the mechanical switch without breaking force has slower breaking and closing speed of mechanical contact points, smaller mechanical impact and higher operation electric life, when the mechanical switch is in a moving state and can generate unexpected mechanical impact (such as collision, rollover and the like), the mechanical switch K can be accidentally closed and broken in a normally open state, or the opening distance is reduced, or impulse voltages are generated at two ends of the mechanical switch K, arcing can occur at the moment, when the control unit A detects arcing in the breaking state of the mechanical switch K (the voltage at the common end of the detection mechanical switch K and the load RL can be known), the control unit A controls the first switch S1 to be conducted for arc extinction.

In the above embodiment, under the working condition that the control unit a detects the arc extinction failure (the control unit a knows according to the voltage or current of the capacitor C1; the control unit a charges the capacitor C1 again and then performs the second arc extinction, the reliability of arc extinction and the response speed of the second arc extinction can be greatly improved.

In the above embodiment, the number of the mechanical switch K, the load RL and the first switch S1 is two or more, the common capacitor C1 and the control unit a (sharing a programmable device) can achieve the purposes of greatly saving cost and reducing volume, in order to effectively overcome the line loss caused by the overlong arc extinguishing loop line of each load RL due to the distribution of the multiple paths of mechanical switches K, provide enough arc extinguishing current for the capacitor C1, promote the arc extinguishing effect, provide the arc extinguishing voltage provided for the load RL higher than the working voltage of the load RL (e.g. the terminal PB is grounded, the charging voltage of the capacitor C1 is greater than the working voltage of the load RL), and connect a voltage to the terminal PB, or reversely charge the capacitor C1, and then supply power to the load RL through superposition of a semiconductor switch and the voltage of the capacitor C1, or supply power to the other capacitor by connecting the voltage to the mechanical switch K, and the voltage provided by the capacitor C1 can also be the external power to couple the voltage of the load RL through the capacitor C1, as required, and connect the terminal PB of the capacitor C1 of fig. 1 to the power supply ground or connect a power supply as required.

The limit of the capacitor to the effective value of the arc extinguishing current is adopted, so that the risk of power supply to other loop loads RL caused by breakdown of the first switch S1 is prevented; the common ends of the mechanical switches K required to be subjected to arc extinction and the load RL are connected through the first switches S1, the first switches S1 of the paths are connected in reverse series, the problem that the mechanical switches K supply power to the load RL connected with the other path of mechanical switches K due to error conduction is avoided, and the device has the advantages of high withstand voltage between the output ends of the mechanical switches K (4000 volts can be easily reached when the first switches S1 adopt unidirectional thyristors), high response speed, small volume, low cost, limitation of limiting the service life of the arc extinction operation times and the like; when the system voltage is higher, the first switch S1 may be a half-controlled device (such as a unidirectional thyristor, where the withstand voltage of the conventional model may reach 1500 to 2000 volts, a unidirectional thyristor with a rated current of 25 amperes may be used to quench a mechanical switch with a current of thousands of amperes, and the quenching pulse current may be controlled between tens of microseconds and 1 millisecond) and one or more diodes (an uncontrollable device, where the conventional withstand voltage of the diode may reach 1000 to 2000 volts, a diode with a rated current of 10 amperes may be used to quench a mechanical switch with a current of thousands of amperes) may be connected in series, so that the insulation withstand voltage between the output ends of the mechanical switches may be greatly improved (easily up to 6000 volts, or more than ten thousand volts).

The arc extinguishing device not only has an intelligent electronic arc extinguishing system for prolonging the electric life of the mechanical switch, but also is a multi-channel mechanical switch management system (multi-channel mechanical switch arc management system), can be used as a multi-channel mechanical switch intelligent management system for calculating the service life of the mechanical switch, forecasting the service life of the mechanical switch, recording the operation times of the mechanical switch and detecting the working state of the mechanical switch under the condition of not increasing hardware resources, can greatly reduce the labor maintenance cost and the operation cost of the system (an electric control system), improve the safety of the system operation, improve the intelligent level of equipment, avoid adopting a heavy and expensive Gao Fenduan-force mechanical switch (changing the original electrical design standard), reduce the environmental pollution caused by frequent switch replacement, have high economic value and social value, and are extremely beneficial to changing the current situation that the electronic arc extinguishing is difficult to popularize.

The switch system of the arc extinguishing device not only combines the advantages of the arc extinguishing device, but also breaks through the design specification of the traditional switch system because the mechanical switch does not have breaking force on load current, and compared with the traditional mechanical switch (with breaking force), the mechanical switch of the switch system has the advantages of small contact opening distance, slower breaking speed (reducing driving power consumption and mechanical impact on the switch), no need of adopting arc extinguishing grid, vacuum or gas-filled arc extinguishing measures, low cost, small closing bounce, large switching-on current, low power consumption, longer mechanical service life, low working noise and small volume.

In the above embodiment, the capacity of the capacitor C1 is preferably that the on time of the first switch S1 is not more than 1 millisecond (preferably within 200 microseconds), and it is recommended that when a certain opening distance exists between the contacts of the mechanical switch K, the breakdown voltage of the opening distance is greater than the working voltage of the mechanical switch K, and the first switch S1 is turned on, so long as the pulse current loaded with tens of microseconds is provided, a satisfactory arc extinguishing effect can be achieved), and the arc extinguishing device of the present invention can easily meet the arc extinguishing frequency of more than hundred times per second; the control unit a drives the first switch S1 using a transformer.

In the above embodiment, the operation reliability of the design selection type second switch S2 is superior to that of the first switch S1.

Note that: the embodiment of the invention is direct current arc extinction (used for a system below 2000V or a system below 1000V), can also be used for alternating current arc extinction (synchronous arc extinction), and can also be added with related components for alternating current arc extinction or bidirectional direct current arc extinction according to the requirement.

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

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

2. The capacitor is adopted to facilitate energy storage and boosting, and can provide electric pulse which is larger than the input power supply voltage of the mechanical switch for a load, and can output extremely large arc extinguishing current (the current of hundreds to thousands of amperes can be transmitted by a 1-square lead) under the conditions of long line, small line diameter and large internal resistance of an arc extinguishing loop.

3. The arc extinguishing energy is known by using the capacitor, so that the first switch is effectively prevented from being damaged, and the influence on other loop loads is effectively prevented.

Claims

1. An arc extinguishing circuit, a mechanical switch requiring arc extinguishing is connected with a load, and is characterized in that: the arc extinguishing circuit is composed of a first capacitor and a first switch, wherein in the breaking process of the mechanical switch, the first capacitor supplies power to the load through the first switch and is used for arc extinguishing of the mechanical switch, the number of the mechanical switch, the load and the first switch is two or more, the first switch is a semiconductor switch, the common ends of the mechanical switch and the load are connected through the first switch, and the first capacitor is connected with the common ends of the first switch.

2. The arc suppressing circuit of claim 1, wherein: the first switches are unidirectional conduction switches, the first switches are semi-controlled switches, and the first switches are connected in series in an opposite direction.

3. The arc suppressing circuit of claim 1, wherein: the first switch is a half-control device; or the first switch is formed by connecting a half-controlled device and an uncontrollable device in series.

4. The arc suppressing circuit of claim 1, wherein: the voltage provided by the first capacitor is greater than the working voltage of the load.

5. The arc suppressing circuit of claim 1, wherein: the first switch comprises a half-control device, a second capacitor and a first diode, wherein the half-control device is connected with the first diode in series, and the voltage of the load or the voltage of the mechanical switch triggers the first switch to be conducted through the second capacitor.

6. The arc chute of claim 5 wherein: the circuit also comprises a second diode and a second resistor, wherein the second diode and the second resistor form a parallel circuit, and the parallel circuit is connected with the second capacitor in series.

7. An arc extinguishing device including the arc extinguishing circuit according to any one of claims 1 to 6, characterized in that: the system also comprises a control unit; the control unit is respectively connected with the first capacitor and the mechanical switch.

8. The arc suppressing apparatus according to claim 7, wherein: the control signal of the first switch is provided by the control unit.

9. The arc suppressing apparatus according to claim 7, 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 switch signal of the mechanical switch is transmitted to the control unit.

10. The arc suppressing apparatus according to claim 7, wherein: the mechanical switch is connected with a unidirectional conduction device in series.

11. The arc suppressing apparatus according to claim 7, wherein: the voltage signal or the current signal of the first capacitor is transmitted to the control unit, and the control unit is used for charging and/or discharging the first capacitor.

12. The arc suppressing apparatus according to claim 11, wherein: the control unit adjusts the charging voltage of the first capacitor according to the current passing through the mechanical switch.

13. The arc suppressing apparatus according to claim 7, wherein: the power supply voltage signal of the input end of the mechanical switch is connected to the control unit.

14. The arc suppressing apparatus according to claim 7, wherein: the voltage signal of the common terminal of the mechanical switch and the load is transmitted to the control unit.

15. The arc suppressing apparatus according to claim 7, wherein: the first capacitor and the second switch form a first series circuit, a voltage signal of a common end of the first series circuit and the first switch is connected to the control unit, and the second switch is a semiconductor switch.

16. The arc suppressing apparatus according to claim 15, wherein: the second switch is a diode and further comprises a first resistor, and a power supply is connected with the common end of the first series circuit and the first switch through the first resistor.

17. The arc suppressing apparatus according to claim 7, wherein: the arc extinguishing device is placed in a shell and is connected with the mechanical switch through a terminal.

18. A switching system comprising the arc extinguishing device of claim 7, characterized by: the mechanical switch is not provided with breaking capacity for the load working current.