CN214798848U - Backup protection device for surge protection device and corresponding circuit protection system - Google Patents

Abstract

The utility model relates to a reserve protective apparatus and corresponding circuit protection system for surge protective equipment. The backup protection device includes: a protection circuit including an input terminal, a switching device, and an output terminal; and a switching device control circuit including a current detection device, a trip control device, and a trip device. The current detection device is used for detecting the current in the protection loop and outputting an electric signal corresponding to the current in the protection loop. The tripping control device is electrically connected to the current detection device and used for generating an action signal when the current in the protection loop is a power frequency current and the current in the protection loop represented by the electric signal is greater than a preset value. The tripping device is electrically connected to the tripping control device and used for generating an action force according to the action signal so as to enable the switching device to change from a closed state to an open state.

Description

Backup protection device for surge protection device and corresponding circuit protection system

Technical Field

The utility model relates to a backup protection equipment especially relates to a backup protection equipment and include surge protection equipment and backup protection equipment's circuit protection system for surge protection equipment.

Background

A backup protection Device of a Surge Protector (SPD) is used to protect the SPD. The current backup protection device can only play a role of protecting the SPD when only surge current or short-circuit current exists in a circuit loop of the backup protection device. However, when both surge current and short-circuit current exist in the circuit loop, the gap for releasing surge energy in the backup protection device is broken down by the surge current, so that the gap is short-circuited, the short-circuit current continuously flows through the gap, the gap is damaged, and the backup protection device cannot protect the SPD.

SUMMERY OF THE UTILITY MODEL

The utility model provides a can be in its circuit loop when having surge current and short-circuit current the two protection Surge Protection Device (SPD) reserve protection equipment and including Surge Protection Device (SPD) and reserve protection device's circuit protection system simultaneously.

According to an embodiment of the present invention, a backup protection device for a Surge Protection Device (SPD) is provided. The backup protection device includes: a protection circuit comprising an input terminal, a switching device, and an output terminal, wherein the input terminal is to receive an input current; the switching device is electrically connected between the input terminal and the output terminal; the output terminal for electrical connection to the surge protection device. The backup protection device further comprises: the switching device control loop comprises a current detection device, a tripping control device and a tripping device, wherein the current detection device is used for detecting the current in the protection loop and outputting an electric signal corresponding to the current in the protection loop; the tripping control device is electrically connected to the current detection device and used for generating an action signal when the current in the protection loop is a power frequency current and the current in the protection loop represented by the electric signal is greater than a preset value; the tripping device is electrically connected to the tripping control device and used for generating an action force according to the action signal so as to change the switching device from a closed state to an open state.

Optionally, the protection circuit further comprises: and the current limiting device is electrically connected between the input terminal and the switching device and is used for limiting the current in the protection loop.

Optionally, the current limiting device comprises a positive temperature coefficient thermistor.

Optionally, the trip control device includes a low-pass filter and a voltage comparator, wherein the low-pass filter is electrically connected to the current detection device, and is configured to filter out a high-frequency component in the electrical signal corresponding to the surge current in the protection loop and pass a low-frequency component in the electrical signal corresponding to the power-frequency current in the protection loop, and output a filtered electrical signal; and the voltage comparator, electrically connected to the low-pass filter, for comparing a reference voltage corresponding to the predetermined value with the voltage of the filtered electrical signal, and generating the action signal when the voltage of the filtered electrical signal is greater than the reference voltage.

Optionally, the trip control device further includes: and the voltage amplifier is electrically connected between the current detection device and the low-pass filter and is used for amplifying the electric signal.

Optionally, the trip control device further includes: and the analog-to-digital converter is electrically connected between the current detection device and the low-pass filter and is used for converting the electric signal into a digital signal, wherein the low-pass filter is a digital low-pass filter.

Optionally, the trip control device is further configured to perform at least one of the following processing on the electrical signal: limiting the voltage of the electrical signal, limiting the current of the electrical signal, decoupling the electrical signal.

Optionally, the trip device includes an electromagnetic trip and a trip mechanism, wherein the electromagnetic trip generates a magnetic force according to the actuating signal, and the magnetic force is used for driving the trip mechanism to generate an actuating force for changing the state of the switch device.

Optionally, the trip mechanism has a display member for indicating the closed state or the open state of the switching device.

According to another embodiment of the present invention, there is provided a circuit protection system, including: a backup protection device as described above, and a surge protection device electrically connected between the backup protection device and the ground terminal.

Drawings

These and/or other aspects, features and advantages of the present invention will become more apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic circuit diagram of a backup protection device according to an embodiment of the present invention;

fig. 2 is another schematic circuit diagram of a backup protection device according to an embodiment of the present invention;

fig. 3 is a schematic circuit diagram of a trip control device according to an embodiment of the present invention;

fig. 4 is another circuit configuration schematic of a trip control apparatus according to an embodiment of the present invention;

fig. 5 shows a schematic diagram of the circuit structure of a backup protection device whose trip device comprises an electromagnetic trip and a trip mechanism according to the present invention; and

fig. 6 is a schematic circuit diagram of a circuit protection system according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below with reference to exemplary embodiments thereof. The invention is not limited to the embodiments described herein, however, which may be embodied in many different forms. The described embodiments are intended only to be exhaustive and complete, and to fully convey the concept of the invention to those skilled in the art. Features of the various embodiments described may be combined with each other or substituted for each other unless expressly excluded or otherwise excluded in context.

In the embodiments of the present invention, unless otherwise specifically stated, "connected" does not mean that "directly connected" or "directly in contact" is necessary, but only needs to be electrically connected.

A backup protection device of a Surge Protector (SPD) is used to protect the SPD. Specifically, the backup protection device of the SPD can distinguish surge current and short-circuit current, and when the short-circuit current occurs, the backup protection device of the SPD can act and disconnect the SPD from a line, so that the SPD cannot be damaged due to overheating and further accidents such as fire and explosion of a circuit system can be caused. The current backup protection device can only play a role of protecting the SPD when only surge current or short-circuit current exists in a circuit loop of the backup protection device, and cannot protect the SPD when both the surge current and the short-circuit current exist. Therefore, the utility model provides a can be in its circuit loop when having surge current and short-circuit current both simultaneously protect SPD's reserve protection equipment and including SPD and this reserve protection equipment's circuit protection system.

First, a circuit configuration of a backup protection apparatus according to an embodiment of the present invention is described with reference to fig. 1. Fig. 1 is a schematic circuit diagram of a backup protection device according to an embodiment of the present invention. As shown in fig. 1, the backup protection apparatus 100 includes a protection circuit 110 and a switchgear control circuit 120. The protection circuit 110 includes an input terminal 111, a switching device 112, and an output terminal 113. Input terminal 111 is used to receive an input current (e.g., from an SPD protected circuit). The switching device 112 is electrically connected between the input terminal 111 and the output terminal 113, and its default state is a closed state. The output terminal 113 is for electrically connecting to the SPD. The switching device control circuit 120 includes a current detection device 121, a trip control device 122, and a trip device 123. The current detection device 121 is used to detect the current in the protection loop 110 and output an electrical signal corresponding to the current in the protection loop 110. The trip control device 122 is electrically connected to the current detection device 121, and is configured to generate an action signal when the current in the protection loop 110 is a power frequency current and the current in the protection loop 110 represented by the electrical signal is greater than or equal to a predetermined value (also referred to as a "first preset value", for example, the first preset value is 1A). The trip device 123 is electrically connected to the trip control device 122, and is configured to generate an actuating force according to the actuating signal to change the switching device 112 from the closed state to the open state. In the present invention, when the input current received by the input terminal 111 in the protection circuit 110 is a surge current, the switching device control circuit 120 does not change the state of the switching device 112, i.e., the switching device 112 is in the closed state. Accordingly, surge current can flow into the SPD through the protection circuit 110, and the SPD can exert a protective effect on the protected circuit. When the input current received by the input terminal 111 in the protection circuit 110 is a power frequency current, the switching device control circuit 120 may control the state of the switching device 112 to change, i.e., control the switching device 112 to change from the closed state to the open state, when the power frequency current is greater than or equal to a first predetermined value. Correspondingly, a small power frequency current can flow into the SPD, but a large power frequency current (such as a short-circuit current) cannot flow into the SPD, so that the SPD is protected, and the SPD cannot be damaged due to overheating. Therefore, when the surge current and the short-circuit current coexist in the protection circuit 110, since the duration of the surge current is very short (for example, several microseconds), the surge current flows into the SPD before the state of the switching device 112 changes (i.e., changes from the closed state to the open state), and the short-circuit current cannot flow into the SPD as a large power frequency current, thereby realizing protection of the SPD by the backup protection apparatus. Therefore, according to the utility model discloses a backup protection equipment has surge current endurance to can protect SPD when there is both surge current and short-circuit current in its circuit loop simultaneously.

According to an example of the present invention, the protection circuit 110 of the backup protection device 100 may further include a current limiting device to limit the current in the protection circuit 110. In particular, the current limiting device may achieve the limiting of the current in the protection loop 110 by limiting the input current received by the input terminal 111 (e.g., by limiting the magnitude of the input current received by the input terminal 111).

For example, when the current detection device 121 can only detect current within a predetermined range and the input current received by the input terminal 111 exceeds the predetermined range, the current detection device 121 will not be able to detect current in the protection loop 110. For this case, a current limiting device may be provided in the protection circuit 110. By providing a current limiting device in the protection loop 110, the current limiting device may limit the input current received by the input terminal 111 to be within the predetermined range, so that the current detecting device 121 can detect the current in the protection loop 110.

For another example, when the input current received by the input terminal 111 is too large, the electrical signal corresponding to the current in the protection circuit 110, which is obtained by the trip control device 122 from the current detection device 121, is strong, and the action signal for driving the trip device 123 to act may be strong, so that the action of the trip device 123 is unsafe. For this case, a current limiting device may also be provided in the protection circuit 110. By providing a current limiting device in the protection circuit 110, the current limiting device can limit the current in the protection circuit 110, so as to ensure the safety of the action of the trip device 123.

The circuit configuration of the backup protection apparatus including the current limiting device will be described below with reference to fig. 2. Fig. 2 is another schematic circuit diagram of a backup protection device according to an embodiment of the present invention. As shown in fig. 2, the backup protection apparatus 200 includes a protection circuit 210 and a switchgear control circuit 220. The protection circuit 210 includes an input terminal 211, a current limiting device 212, a switching device 213, and an output terminal 214. Input terminal 211 is similar to input terminal 111 in fig. 1 for receiving an input current (e.g., from an SPD protected circuit). The current limiting device 212 is electrically connected between the input terminal 211 and the switching device 213 for limiting the current in the protection circuit 210. The switching device 213 is electrically connected between the current limiting device 212 and the output terminal 214, and has a default state of a closed state, similar to the switching device 112 of fig. 1. The output terminal 214 is similar to the output terminal 113 in fig. 1 for electrical connection to the SPD. In addition, the switchgear control circuit 220 in fig. 2 is similar to the switchgear control circuit 120 in fig. 1, and includes a current detection device 221, a trip control device 222, and a trip device 223. The current detection device 221 is similar to the current detection device 121 in fig. 1. Specifically, the current detection device 221 is used for detecting the current in the protection loop 210, specifically, the current after being limited by the current limiting device 212. In addition, trip control 222 is similar to trip control 122 of fig. 1, and trip 223 is similar to trip 123 of fig. 1.

The current limiting device 212 may be any circuit configuration capable of limiting the current in the protection loop. For example, the current limiting device 212 may be a circuit structure whose resistance value increases as the temperature of the current limiting device 212 increases. According to an example of the present invention, the current limiting device 212 may include a positive temperature coefficient thermistor. Alternatively, according to another example of the present invention, the current limiting device 212 may include any combination of resistors with a constant resistance, a positive temperature coefficient thermistor, or a negative temperature coefficient thermistor.

In an example where the current limiting device 212 is a circuit structure whose resistance value increases with an increase in the temperature of the current limiting device 212, the current limiting device 212 may have a high temperature sensitivity, for example, it can sense a temperature change of 6 to 10 degrees celsius. When the temperature of the current limiting device 212 reaches the temperature sensitivity, the resistance of the current limiting device 212 changes with the temperature (e.g., the resistance of the current limiting device 212 increases with the temperature), i.e., the current limiting effect of the current limiting device 212 increases with the temperature.

When the input current received by the input terminal 211 is a surge current, since the duration of the surge current is very short (e.g., several microseconds), the energy generated by the current limiting device 212 is very weak, and accordingly, the temperature of the current limiting device 212 varies very slightly (e.g., is substantially negligible), so that the current limiting device 212 cannot sense the temperature variation, and thus the resistance value of the current limiting device 212 does not vary. Therefore, in this case, the current limiting effect of the current limiting device 212 is weak.

In addition, when the input current received by the input terminal 211 is the power frequency current and the power frequency current is less than or equal to the second predetermined value (for example, 15kA), although the duration of the power frequency current is long, the temperature change of the current limiting device 212 caused by the energy generated by the current limiting device 212 cannot be sensed by the current limiting device 212, and therefore, the resistance value of the current limiting device 212 does not change. Therefore, in this case, the current limiting effect of the current limiting device 212 is also weak.

Conversely, when the input current received at input terminal 211 is a power frequency current and the power frequency current is greater than a second predetermined value (e.g., 15kA), the temperature change of current limiting device 212 caused by the energy generated by current limiting device 212 can be sensed by current limiting device 212, and thus the resistance of current limiting device 212 will change with the temperature change. Therefore, in this case, the current limiting device 212 will exert a large current limiting effect. Additionally, the utility model discloses in, the power frequency electric current that is greater than the second predetermined value can be called power frequency short-circuit current.

In the present disclosure, the current limiting device 212 may limit the current in the protection circuit 110 to a predetermined level. The predetermined level may be, for example, 1 to 2 kA.

In the present invention, the current detection device (e.g., the current detection device 121 in fig. 1 or the current detection device 221 in fig. 2) may be any circuit structure capable of detecting the current in the protection circuit. For example, the current detection device 121 in fig. 1 or the current detection device 221 in fig. 2 may be a current sensor, such as a current transformer or the like. The current transformer may include a closed core and windings, wherein the windings include a first winding (also referred to as a primary winding) connected in series in a protection loop and a second winding (also referred to as a secondary winding) connected in series in a circuit loop of the trip control device. Similarly, the current sensor may also employ a rogowski coil.

As described above, the trip control device (e.g., the trip control device 122 in fig. 1 or the trip control device 222 in fig. 2) may generate the action signal when the current in the protection loop is the power frequency current and the current in the protection loop represented by the electrical signal obtained from the current detection device is greater than or equal to the first predetermined value. The specific circuit structure of the trip control device 222 will be described below with reference to fig. 3 and 4 by taking the trip control device 222 in fig. 2 as an example.

Fig. 3 is a schematic circuit diagram of the trip control device 222 according to an embodiment of the present invention. As shown in fig. 3, the trip control device 222 may include a low pass filter 2221 and a voltage comparator 2222. The low pass filter 2221 may be electrically connected to the current detection device 221, which is configured to filter a high frequency component corresponding to a surge current in the protection loop from the electrical signal and pass a low frequency component corresponding to a power frequency current in the protection loop from the electrical signal, and output the filtered electrical signal. The voltage comparator 2222 may be electrically connected to the low pass filter 2221 for comparing a reference voltage corresponding to the first predetermined value described above with the voltage of the filtered electric signal, and generating a signal when the voltage of the filtered electric signal is greater than the reference voltage. The signal may be an action signal as described above.

Since the frequency of the surge current is high and the frequency of the line-frequency current is low, when the current in the protection circuit is the surge current, the electric signal output from the current detection device 221 includes a high-frequency component corresponding to the surge current. In the case where the current in the protection circuit is a power frequency current, the electrical signal output by the current detection device 221 will include a low frequency component corresponding to the power frequency current. When a surge current and a power frequency current coexist in the protection circuit, the electric signal output from the current detection device 221 will include a high frequency component corresponding to the surge current and a low frequency component corresponding to the power frequency current. The low-pass filter 2221 is arranged to filter out a high-frequency component corresponding to the surge current in the electrical signal output by the current detection device 221, and to allow a low-frequency component corresponding to the power frequency current in the electrical signal output by the current detection device 221 to pass, so that the trip control device 222 does not output an operation signal when the current in the protection loop is the surge current, thereby avoiding false operation of the trip device due to the surge current.

In addition, the filtering time of the low pass filter 2221 may be set. For example, the filtering time of the low pass filter 2221 may be set to a preset time period (e.g., 20 msec) after the current detection device 221 outputs the electric signal. Since the duration of the surge current is very short (e.g., several microseconds), by setting the filtering time of the low pass filter 2221, the filtering of the high frequency component corresponding to the surge current in the electrical signal can be further ensured.

In addition, since some disturbances (e.g., noise signals) may cause a small power frequency current to always exist in the protection loop, the trip control device 222 controls the trip device to operate (e.g., trip) if the power frequency current exists in the protection loop, which may cause the trip device to operate frequently. This not only causes wear to the trip device, reducing the life of the trip device, but also makes the user experience very poor. In order to improve the anti-interference ability of the trip control device 222, the utility model provides a set up the voltage comparator 2222 in the trip control device 222 for the trip control device 222 just outputs the actuating signal when the power frequency current in the protection loop is greater than or equal to first predetermined value, thereby controls the trip device action (for example, the dropout).

For the reference voltage described above, the value thereof may be related to the first predetermined value described above. For example, when the current in the protection circuit is a power frequency current and the magnitude of the power frequency current is a first predetermined value, the voltage of the electrical signal output by the current detection device 221 may be detected, and the detected voltage may be used as a reference voltage.

Fig. 4 is another schematic circuit diagram of the trip control device 222 according to an embodiment of the present invention. As shown in fig. 4, the trip control device 222 may further include a voltage amplifier 2223 electrically connected between the current detection device 221 and the low pass filter 2221 for amplifying the electrical signal (e.g., amplifying the voltage of the electrical signal) output by the current detection device 221. This is helpful in situations where the electrical signal output by the current sensing means 221 is weak. By providing the voltage amplifier 2223, the electrical signal output by the current detection device 221 can be amplified, so that a subsequent circuit can recognize that the electrical signal is output by the current detection device 221 and process the electrical signal accordingly.

In the case where the trip control device 222 includes the voltage amplifier 2223, the value of the reference voltage described above may be related not only to the first predetermined value described above but also to the amplification capability of the voltage amplifier 2223. For example, the value of the reference voltage may be proportional to the amplification capability of the voltage amplifier 2223. When the amplification capability of the voltage amplifier 2223 is strong, the value of the reference voltage may be large; conversely, when the amplification capability of the voltage amplifier 2223 is weak, the value of the reference voltage may be small.

In the present invention, the electrical signal output by the current detection device 221 may be an analog signal. Accordingly, the low pass filter 2221 described above may be an analog low pass filter.

Alternatively, the low pass filter 2221 described above may also be a digital low pass filter. In this case, the trip control device 222 may further include an analog-to-digital converter 2224, which may be electrically connected between the current detection device 221 and the low pass filter 2221, for converting the electrical signal into a digital signal. In the example shown in fig. 4, the analog-to-digital converter 2224 may be electrically connected between the voltage amplifier 2223 and the low pass filter 2221. For digital signals, some processing (e.g., squaring) may be performed on the digital signal before being filtered by a low pass filter.

Furthermore, the trip control device (e.g., the trip control device 122 in fig. 1 or the trip control device 222 in fig. 2) may further perform at least one of the following processes on the electrical signal corresponding to the current in the protection loop acquired from the current detection device: limiting the voltage of the electrical signal, limiting the current of the electrical signal, decoupling the electrical signal. For example, as shown in fig. 4, one or more resistors (R) may be connected in series between the voltage amplifier 2223 and the analog-to-digital converter 2224 to limit the voltage and/or current of the electrical signal. Furthermore, as shown in fig. 4, a decoupling capacitance (C) may be added between the input terminal and the ground terminal of the analog-to-digital converter 2224 to achieve decoupling of the electrical signals.

In the present invention, a trip device (e.g., the trip device 123 of fig. 1 or the trip device 223 of fig. 2) may include an electromagnetic trip and a trip mechanism, wherein the electromagnetic trip generates a magnetic force according to an operation signal from a trip control device. The magnetic force is used to drive the trip mechanism to generate an actuating force that changes the state of the switchgear. For example, the magnetic force may be used to overcome a counter spring in the electromagnetic release to engage an armature in the electromagnetic release to strike a pull rod in the electromagnetic release, thereby causing the release mechanism to act (e.g., trip) to generate an actuating force that changes the state of the switchgear.

Alternatively, the trip device (e.g., the trip device 123 of fig. 1 or the trip device 223 of fig. 2) may include a relay that generates a magnetic force according to an action signal from the trip control device and a trip mechanism. The magnetic force is used to drive the trip mechanism to generate an actuating force that changes the state of the switchgear. For example, the magnetic force may operate a trip mechanism (e.g., trip) to generate an actuating force that changes the state of the switching device.

Fig. 5 shows a schematic diagram of a circuit configuration of a backup protection device whose trip device comprises an electromagnetic trip and a trip mechanism according to the present invention. As shown in fig. 5, backup protection device 500 may include a protection circuit 510 and a switchgear control circuit 520. The protection circuit 510 is similar to the protection circuit 210 of fig. 2, and includes an input terminal 511, a current limiting device 512, a switching device 513, and an output terminal 514. The switchgear control circuit 520, similar to the switchgear control circuit 220 of fig. 2, includes a current detection device 521, a trip control device 522, and a trip device 523. The trip device 523 may include an electromagnetic trip 5231 and a trip mechanism 5232. The electromagnetic release 5231 generates a magnetic force based on an actuation signal from the trip control device 522, which can be used to attract an armature in the electromagnetic release 5231 against a counter spring in the electromagnetic release 5231 to strike a pull rod 52311 in the electromagnetic release 5231, causing the pull rod 52311 to strike the trip mechanism 5232, thereby actuating (e.g., tripping) the trip mechanism 5232 to generate an actuation force that changes the state of the switchgear.

In addition, the trip device (e.g., trip device 123 of fig. 1 or trip device 223 of fig. 2) may have a display part. The display member may be used to indicate the closed state or the open state of the switching device. For example, the display component may detect whether the trip device 123 in fig. 1 or the trip device 223 in fig. 2 is actuated (e.g., tripped), and may indicate whether the trip device 123 in fig. 1 or the trip device 223 in fig. 2 is actuated (e.g., tripped) in various suitable manners, thereby indicating the closed state or the open state of the switching device. The various suitable means include, for example, one or more of text, sound, or images. In an example where the display part indicates whether the trip device 123 in fig. 1 or the trip device 223 in fig. 2 is tripped through a letter, in a case where the trip device 123 in fig. 1 or the trip device 223 in fig. 2 is not tripped, the switching device is in a closed state, and then the display part may display a letter "ON" to indicate that the switching device is in the closed state; in the case where the trip device 123 of fig. 1 or the trip device 223 of fig. 2 is tripped, the switching device is in the OFF state, and the display part may display a text "OFF" to indicate that the switching device is in the OFF state.

In the present invention, the switching device (e.g., the switching device 112 in fig. 1 or the switching device 213 in fig. 2) has an isolation function. For example, the switching device may be a set of contacts. In particular, the switching device 112 of fig. 1 or the switching device 213 of fig. 2 may isolate the voltage at the switching device from the voltage at the trip device. For example, when the switching device is in a closed state and the current in the protection loop is too large, resulting in too high voltage at the switching device, the switching device may isolate the high voltage at the switching device from the voltage at the trip device, thereby ensuring that the trip device is within a safe voltage range.

The utility model also provides a circuit protection system. A circuit protection system according to the present invention will be described below with reference to fig. 6. Fig. 6 is a schematic circuit diagram of a circuit protection system according to an embodiment of the present invention. As shown in fig. 6, the circuit protection system 600 includes a backup protection device 610, and a Surge Protection Device (SPD)620 electrically connected between the backup protection device 610 and a ground terminal. The backup protection device 610 may be the backup protection device 100 of fig. 1 or the backup protection device 200 of fig. 2 or the backup protection device 500 of fig. 5 described above. The utility model discloses a circuit protection system has surge current endurance to protection SPD when can have surge current and short-circuit current two simultaneously in the circuit loop of backup protection equipment.

The block diagrams of circuits, devices, apparatus, devices, and systems presented herein are meant to be illustrative examples only and are not intended to require or imply that the blocks, devices, and systems shown in the block diagrams must be connected or arranged or configured in a manner consistent with the teachings of the block diagrams. As will be appreciated by one skilled in the art, these circuits, devices, apparatus, devices, systems may be connected, arranged, configured in any manner that achieves the intended purposes.

It should be understood by those skilled in the art that the foregoing specific embodiments are merely exemplary and not limiting, and that various modifications, combinations, sub-combinations and substitutions may be made in the embodiments of the invention depending upon design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Claims (10)

1. A backup protection device for a surge protection device, comprising:

a protection circuit including an input terminal, a switching device and an output terminal, wherein

The input terminal is used for receiving input current;

the switching device is electrically connected between the input terminal and the output terminal;

the output terminal for electrical connection to the surge protection device;

a switching device control circuit comprises a current detection device, a trip control device and a trip device, wherein

The current detection device is used for detecting the current in the protection loop and outputting an electric signal corresponding to the current in the protection loop;

the tripping control device is electrically connected to the current detection device and used for generating an action signal when the current in the protection loop is a power frequency current and the current in the protection loop represented by the electric signal is greater than a preset value;

the tripping device is electrically connected to the tripping control device and used for generating an action force according to the action signal so as to change the switching device from a closed state to an open state.

2. A backup protection device according to claim 1, wherein said protection circuit further comprises:

and the current limiting device is electrically connected between the input terminal and the switching device and is used for limiting the current in the protection loop.

3. A backup protection device according to claim 2, characterized in that said current limiting means comprise a positive temperature coefficient thermistor.

4. Backup protection device according to any of claims 1 to 3, characterized in that the trip control means comprise a low-pass filter and a voltage comparator, wherein

The low-pass filter is electrically connected to the current detection device and is used for filtering out a high-frequency component in the electric signal corresponding to surge current in the protection loop, enabling a low-frequency component in the electric signal corresponding to power frequency current in the protection loop to pass through, and outputting a filtered electric signal; and

the voltage comparator, electrically connected to the low pass filter, is used for comparing a reference voltage corresponding to the predetermined value with the voltage of the filtered electric signal, and generating the action signal when the voltage of the filtered electric signal is greater than the reference voltage.

5. The backup protection device of claim 4, wherein said trip control means further comprises:

and the voltage amplifier is electrically connected between the current detection device and the low-pass filter and is used for amplifying the electric signal.

6. The backup protection device of claim 4, wherein said trip control means further comprises:

an analog-to-digital converter electrically connected between the current detection device and the low-pass filter for converting the electrical signal into a digital signal,

wherein the low pass filter is a digital low pass filter.

7. The backup protection device of any of claims 1 to 3, wherein said trip control means is further configured to perform at least one of the following processing on said electrical signal: limiting the voltage of the electrical signal, limiting the current of the electrical signal, decoupling the electrical signal.

8. A backup protection device according to any of claims 1 to 3, characterized in that said trip means comprise an electromagnetic trip and a trip mechanism, wherein said electromagnetic trip generates a magnetic force in dependence of said actuation signal, said magnetic force being used to drive said trip mechanism to generate an actuation force that changes the state of said switching device.

9. The backup protection device of claim 8, wherein said trip mechanism has a display member for indicating a closed state or an open state of said switching device.

10. A circuit protection system, comprising:

a backup protection device according to any one of claims 1 to 9; and

and the surge protection equipment is electrically connected between the backup protection equipment and the grounding terminal.

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