JP3834526B2 - Arc reduction method and arc reduction device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc reduction method and an arc reduction device for reducing an adverse effect of an arc on an electric circuit when an arc occurs in an electric circuit such as an electric circuit for a vehicle.
[0002]
[Prior art]
Recently, in various vehicles such as automobiles, a 42V power supply tends to be used instead of a conventional 14V power supply as a power supply for an electric circuit for the vehicle. And, in the various electrical components (for example, headlamps, electric power window devices, etc.) of each part of the vehicle that becomes an electric load from the 42V power source (battery), a connector is formed so that a large number of harnesses (covered electric wires) constitute an electric circuit. Etc. are connected and wired. Further, in the electric circuit, a mechanical relay, a switch, and the like are connected in order to control the various electrical components. In addition, a protective fuse typified by a blade-type fuse is interposed in the electric circuit, and when a continuous large current flows through the electric circuit, the fuse is blown to forcibly current. The circuit can be cut off to protect the circuit.
[0003]
[Problems to be solved by the invention]
However, the harness wired between the power source and each electric load to constitute the electric circuit may be rubbed off against the vehicle body or the like when the vehicle vibrates or the like. When the peeled portion comes into contact with the vehicle body, a so-called rare short may occur. Then, when the sheath peeling portion of the harness is separated from the vehicle main body in such a rare short state, an arc is generated. The arc thus generated usually continues for a long time of several ms to several tens of ms and continues without being extinguished naturally (an example is shown by a broken line in FIG. 3A). Moreover, such an arc is generated between the respective terminal contacts even when the circuit is opened by a mechanical relay or a switch connected in the electric circuit and when the connector is detached.
[0004]
In particular, since the power supply voltage is higher in a circuit in which a 42 V power supply is used as a power supply than in a circuit in which a 14 V power supply is used, the influence of heat (arc heat) generated by the generated arc is greatly increased. For this reason, the arc heat may cause smoke or fire of the insulation coating at the portion where the rare short occurs, contact melting or failure of switches such as mechanical relays, and damage to the connector terminals. As countermeasures, arc countermeasures have conventionally been implemented for mechanical relays, switches, and connectors of electric circuits adopting a 42V power supply. However, the countermeasures increase the size and cost of parts. It was causing the problem.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to instantaneously extinguish an arc when an arc occurs in an electric circuit, and to minimize the adverse effects of the arc on the electric circuit. An object of the present invention is to provide an arc reduction method and an arc reduction apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the current value of the current flowing from the power source of the electric circuit to the electric load is detected, and the detected current value is set as a current value condition at the time of arc occurrence. An arc reduction method for forcibly turning off the electric circuit and forcibly extinguishing the arc when a predetermined condition is satisfied And, as the predetermined condition, when the detected current value becomes less than a predetermined arc determination threshold value, the electric circuit is forcibly cut off. This is the gist.
[0008]
Also, Claim 1 In the invention described in ,in front The gist of the invention is that the detected current value is detected at a predetermined sampling interval, and the arc determination threshold is set to a value obtained by multiplying the detected current value at the previous sampling by a predetermined ratio.
[0009]
Claim 2 In the invention described in claim 1 The gist of the invention is that the sampling interval is set to be shorter than the time required for extinguishing the arc when an arc is generated in the electric circuit.
[0010]
In invention of Claim 3, In the invention according to claim 1 or 2 After the time when the electric circuit is forcibly cut off and the time required for arc extinction has elapsed, the electric circuit is forcibly cut off so that the current supply state from the power source to the electric load is turned on. The gist is to cancel the state.
[0011]
Claim 4 In the invention described in claim 2 Or claim 3 In the invention described in (1), the off time when the electric circuit is forcibly cut off is set to a very short time during which the arc is surely extinguished and does not affect the behavior of the electric load. And
[0012]
Claim 5 According to the invention, the switch means for switching on and off the current supply state from the power supply of the electric circuit to the electric load, the detection means for detecting the current value of the current flowing from the power supply to the electric load, and the detection current by the detection means Control means for switching and driving the switch means so that the current supply state is turned off when a value satisfies a predetermined condition which is a current value condition at the time of arc occurrence, and the control means comprises the detection The gist of the invention is that the switch means is driven to be switched in the off direction when the detected current value by the means becomes less than a predetermined arc determination threshold value.
[0014]
Also, Claim 5 In the invention described in ,in front The detection means is configured to detect a current value at a predetermined sampling interval, and the arc determination threshold is set to a value obtained by multiplying a detection current value at the previous sampling by the detection means by a predetermined ratio. The gist.
[0015]
Claim 6 In the invention described in claim 5 The gist of the invention is that the sampling interval by the detection means is set to be shorter than the time required for extinguishing the arc when an arc occurs in the electric circuit.
[0016]
Claim 7 In the invention described in claim 6 In the invention described above, the control means turns on the current supply state after a lapse of time required for arc extinction after switching the switching means so that the current supply state is turned off. The gist is to drive the switch means so as to be in a state.
[0017]
Claim 8 In the invention described in claim 6 Or claim 7 In the invention described in (1), the off time when the electric circuit is forcibly cut off is set to a very short time during which the arc is surely extinguished and does not affect the behavior of the electric load. And
[0018]
Therefore, claims 1 to claim 8 In the invention described in (1), when the detected current value satisfies a predetermined condition that is a current value condition at the time of arc occurrence, the electric circuit is forcibly cut off and the arc is forcibly extinguished. Therefore, when an arc occurs in the electric circuit, the arc is instantaneously extinguished, so that the adverse effect of the arc on the electric circuit is minimized.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in an arc reduction device and an arc reduction method in an electric circuit for an automobile will be described with reference to FIGS.
[0020]
As shown in FIG. 1A, an arc reduction device F according to this embodiment includes a conductive plate 11, an input terminal 12, an FET (power MOSFET) 13 as a switching means, a relay electrode 14, a detection unit 15, and an output terminal. 16, IC 17, signal input terminal 18, and the like. The arc reduction device F is configured as an IPS (Intelligent Power Switch) in which the conductive plate 11 to the signal input terminal 18 are molded and molded with a molding material 19 such as an epoxy resin, and the whole is formed into a flat hexagonal shape. Has been.
[0021]
An L-shaped branch piece 11a projects from the conductive plate 11, and a thin wall shape corresponding to the current carrying capacity of the fuse is provided between the branch piece 11a and the relay electrode 14 disposed opposite to the branch piece 11a. The detection unit 15 is integrally connected. An inner end portion of an output terminal 16 is attached to the branch piece 11a, and the output terminal 16 protrudes outward in an L shape on one side surface of the package.
[0022]
The input terminal 12 has an outer end projecting outwardly in an L shape on the same side as the side on which the output terminal 16 of the package is mounted, and the FET 13 is placed on the inner surface of the inner end of the input terminal 12. It is fixed. The inner end of the input terminal 12 is connected to the IC 17 via a power input line 12a. The source of the FET 13 is connected to the relay electrode 14 via the conductive bar 20, and the drain is connected to the input terminal 12. The gate of the FET 13 is connected to the IC 17 via the control line 21. Connected to the IC 17 are a + side input line 24 connected to the relay electrode 14 and a − side input line 25 connected to the conductive plate 11.
[0023]
Further, the ground terminal 27 of the arc reducing device F has an outer end projecting outwardly in an L shape on the side surface of the same package as the input terminal 12 and the output terminal 16, and the inner end is connected to the lead wire 27a. Via the IC 17. Similarly, the signal input terminal 18 has an outer end protruding from the package on the same side surface of the package as the output terminal 16, and an inner end connected to the IC 17 via a lead wire 18a.
[0024]
The arc reduction device F configured as described above is attached to a terminal block (not shown) provided in an electric circuit for an automobile. The input terminal 12 is connected to a battery B as a power source of the automobile, and the output terminal 16 is connected to an electrical load (hereinafter also referred to as “load”) 29 via a connector 28. The load 29 is composed of, for example, a headlamp or an electric power window device. The signal input terminal 18 is connected to an external switch 30 as an external switch circuit of the automobile. When the external switch 30 is turned on, a switch-on signal is input to the IC 17 and when the external switch 30 is turned off, the IC 17 is connected. A switch-off signal is input.
[0025]
The IC 17 includes a determination unit 31, an operational amplifier 32, and a driver circuit 33 as control means. The operational amplifier 32 is connected to the + side input line 24 and the − side input line 25, and amplifies the voltage (potential difference) at both ends of the detection unit 15 input via the + side input line 24 and the − side input line 25. The value is input to an A / D conversion input unit (not shown) of the determination unit 31. Since the voltage (potential difference) across the detection unit 15 is proportional to the current value flowing through the detection unit 15, the determination unit 31 detects the voltage across the detection unit 15, thereby determining the current flowing from the battery B to the load 29. The current value can be detected. In the present embodiment, the detection unit 15 and the operational amplifier 32 constitute detection means, and the current value is detected at a predetermined sampling interval (for example, 0.2 ms). In the present embodiment, the determination unit 31 is configured by a microcomputer.
[0026]
The gate of the FET 13 and the determination unit 31 are connected via a driver circuit 33. The determination unit 31 sends a circuit control signal from the driver circuit 33 to the gate of the FET 13 to switch the FET 13 between the on state and the off state. . The determination unit 31 includes a central processing unit (not shown), a ROM that stores an “arc reduction control program”, and a working memory (RAM) that stores various data.
[0027]
Next, an arc reduction control processing routine executed by the determination unit 31 provided in the arc reduction device F having the above configuration will be described with reference to the flowchart shown in FIG.
First, when a predetermined voltage is supplied from the battery B, the determination unit 31 detects, in step S1, a detection current value (previous value) Sb at the previous sampling, a detection current value (current value) Sn at the current sampling, The forced off time counter CNT is reset to “0”. Further, the determination unit 31 resets the switch input state status Lon (0: non-input state, 1: input state) and the cut-off determination status FLG (0: non-cut-off state, 1: cut-off state) to “0”. Set, and go to step S2.
[0028]
In step S2, the determination unit 31 determines whether a switch-on signal is input. If the external switch 30 is off and no switch-on signal is input, the determination unit 31 proceeds to step S3. On the other hand, if the external switch 30 is on and a switch-on signal is input, the determination unit 31 proceeds to step S4.
[0029]
In step S3, the determination unit 31 sets the value of the switch input state status Lon to “0” (non-input state), outputs a circuit off signal to the gate of the FET 13, and turns off the FET 13. And the judgment part 31 returns to step S2 after 0.2 ms which is a sampling interval progress.
[0030]
In step S4, the determination unit 31 determines whether or not the blocking determination status FLG is “0” (non-blocking state). If “0”, the process proceeds to step S5, and if not “0”, that is, “1”. If it is (blocking state), the process proceeds to step S9.
[0031]
In step S5, the determination unit 31 sets the value of the switch input state status Lon to “1” (input state), outputs a circuit-on signal to the gate of the FET 13 via the driver circuit 33, turns on the FET 13, and loads 29 Energize.
[0032]
In step S6, the determination unit 31 detects and captures the current value S by the detection unit 15, and substitutes the current value S for the current value Sn.
In step S7, the determination unit 31 determines whether or not “previous value Sb−current value Sn> arcing descent reference value (hereinafter also referred to as“ descent reference value ”) K” is established as a predetermined condition. To do. If the condition is satisfied, the determination unit 31 proceeds to step S8. If not satisfied, the determination unit 31 returns to step S2 after 0.2 ms, which is the sampling interval.
[0033]
Since the reference value K is a value of the previous value Sb × the rate of descent at arc a (for example, a = 0.15), the conditional expression: previous value Sb−current value Sn> descent amount reference value K is Conditional expression: Previous value Sb × (1−arc descent rate a)> current value Sn. Therefore, the process of step S7 is an arc determination in which the detected current value at the current sampling (current value Sn) is a value obtained by multiplying the detected current value at the previous sampling (previous value Sb) by a predetermined ratio (1-a). This is equivalent to switching the switching means (FET 13) in the off direction when it is less than the threshold for use (previous value Sb × (1-a)).
[0034]
In step S8, the determination unit 31 sets the value of the blocking determination status FLG to “1” (blocking state). Further, the determination unit 31 puts the current value Sn in the previous value Sb.
In step S9, the determination unit 31 increments the value of the forced off time counter CNT by one.
[0035]
In step S10, the determination unit 31 determines whether or not the value of the forced off time counter CNT is greater than the number of forced off times C. If it is larger, the process proceeds to step S11. Return to.
[0036]
In step S11, the determination unit 31 sets the value of the forced OFF time counter CNT and the value of the cutoff determination status FLG to “0” (non-blocking state), and outputs a circuit ON signal to the gate of the FET 13 via the driver circuit 33. The FET 13 is turned on and the load 29 is energized. Then, the determination unit 31 returns to S2 after 0.2 ms which is the sampling interval has elapsed.
[0037]
By the way, when an arc is generated in the electric circuit as in this embodiment, the current value after the arc is generated is smaller than that before the arc is generated. The reason is that when an arc is generated, air resistance is generated in the electrode space of the arc generating portion, and the circuit resistance after the generation is increased as compared with the circuit resistance before the generation. The arc reduction device F according to the present embodiment determines whether or not an arc has occurred by capturing such a change phenomenon of the current value when the arc is generated.
[0038]
In general, a current value drop phenomenon is significantly observed immediately after the occurrence of an arc as compared to before the occurrence, but after a certain fall, the current value gradually decreases to draw a gentle waveform until the arc is extinguished. Accordingly, as the current detection sampling interval is longer, the amount of decrease in the current value is larger, so the setting of the amount of decrease reference value K is easier. However, in order to make the influence of the arc as small as possible, the circuit interruption should be judged immediately after the occurrence of the arc and the arc should be forcibly extinguished as soon as possible. Even if it is necessary to set a small value, it is desirable to shorten it. For example, in a 42 V power supply circuit, experimentally, the current value after 0.1 ms of arcing falls to about 70% to 85% of the current value before arcing, and about 60% to 75% after 0.2 ms. It has been confirmed that it will fall. For this reason, for example, when the sampling interval is 0.2 ms, the descent amount reference value K for determining the cutoff is appropriately about the previous value Sb × 0.15 (arc descent rate a) with a margin.
[0039]
When it is determined that an arc has occurred, the circuit is forcibly cut off during a forced off time T as a constant off time by a semiconductor relay (FET 13) by a circuit off signal. This forced off time T must be a very short time that does not affect the load operation, but it must be a time to extinguish the generated arc sufficiently. For example, assuming that the time during which the arc is sufficiently extinguished when the circuit corresponding to the forced off time T is interrupted is 1 to 2 ms, for example, when the sampling interval is 0.2 ms, the number of forced off times is 5 to 10 times.
[0040]
Next, the operation of the arc reducing device F when an arc is generated in the electric circuit of the present embodiment due to the occurrence of a rare short will be described with reference to the graphs of FIGS. In the example shown in this graph, the sampling interval is 0.2 ms, the forced off time is 1.8 ms, and the number of forced off times is 8.
[0041]
As shown in FIGS. 3A and 3B, in the state where the external switch 30 is on and a predetermined voltage is supplied from the battery B, the determination unit 31 goes through step S1 and step S2 after time t = 0 ms. The process of step S2 and steps S4 to S7 is repeated every sampling interval of 0.2 ms. In this state, a steady current (5 A in this case) flows through the load 29.
[0042]
When the vehicle is vibrated or the like, the insulation coating of the harness wired between the power source and the load 29 is rubbed and peeled off to the vehicle main body, etc. Occur. In FIG. 3A, a rare short-circuit occurs at time t1, and the current value S increases rapidly, resulting in an overcurrent (22.5 A in this case). And when the sheath peeling part of a harness leaves | separates from a vehicle main body at the time t2 from the rare short state, an arc will generate | occur | produce at the time t2.
[0043]
Then, immediately after time t2, the current value S suddenly drops. At time t3 after 0.2 ms elapses, the previous value Sb−current value Sn> drop amount reference value K is established, and at step t8, at time t3, FIG. As shown in FIG. 4, the circuit control signal is set to 0V. Then, a circuit off signal is output as a circuit control signal via the driver circuit 33, the FET 13 is turned off, the current flowing to the load 29 is cut off as shown in FIG. 3A, and the current value S becomes 0A. Become.
[0044]
Further, since “1” is set in the interruption determination status FLG in step S8, the determination unit 31 samples the processes in steps S2, S4, S9, and S10 until the forced OFF time counter CNT> forced OFF count C is satisfied. Repeat at every interval. Note that while such processing is repeatedly performed, the circuit control signal remains at 0 V and the current flowing through the load 29 remains at 0 A. This forced off time lasts 1.8 ms, so that the arc is fully extinguished.
[0045]
On the other hand, when the forced off time T elapses from the time t3 and the time t4 is reached and the forced off time counter CNT> forced number of times C is established, the circuit control signal is set to 5 V and the circuit on signal is output. Is turned on again, and the current flowing to the load 29 becomes 5A.
[0046]
Further, the arc is not limited to a rare short-circuit, but may be generated by the disconnection of the connector 28 or the opening operation of switches such as a mechanical relay (not shown) connected in series in the electric circuit. In this case, the current value drops from the steady current 5A immediately after the arc is generated, and the arc generation state is continued while gradually decreasing until the arc is extinguished. Accordingly, the determination unit 31 detects a current drop of the current value from the steady current 5A, and determines that an arc has occurred when the condition of the previous value Sb−current value Sn> drop amount reference value K is satisfied. That is, when the current value Sn falls below 5.0 A × 0.85 = 4.25 A, the determination unit 31 determines that an arc has occurred and turns off the FET 13 to extinguish the arc.
[0047]
Therefore, this embodiment has the following effects.
(1) Current behavior is monitored by an IPS sensor (detection unit 15), and when an arc occurs, the circuit is cut off for a short time (forced off time T) by an IPS semiconductor relay (FET 13), etc. Has reduced the harmful effects. Therefore, when an arc occurs in the electric circuit, the arc can be extinguished instantaneously, and the adverse effect of the arc on the electric circuit can be minimized.
[0048]
(2) Since the arc can be reduced as described above, conventional products can be used without taking special measures to reduce the arc for mechanical relays, switches, connectors, etc. connected in the electric circuit. An inexpensive configuration.
[0049]
(3) Since the arc can be reduced as described above, it is possible to reduce complexity during maintenance of a circuit that is difficult to maintain when the battery B is removed, in other words, a circuit that is easier to maintain in the energized state. In addition, the risk of a vehicle fire during a rare short can be reduced.
[0050]
(4) When previous value Sb−current value Sn> drop amount reference value K is satisfied, that is, current value Sn is less than the threshold for arc determination (previous value Sb × (1−arc drop rate a)). In this case, the FET 13 is turned off. Therefore, it is possible to determine the occurrence of an arc with a relatively simple circuit configuration.
[0051]
(5) Since the presence / absence of arc occurrence is determined using the difference between the previous value Sb and the current value Sn at each sampling time, for example, the FET 13 is turned off when the current value S becomes smaller than a certain determination reference value. Unlike arc control, etc., even if an arc is generated when the current is higher than the steady load current due to a short circuit, the arc can be immediately reduced.
[0052]
(6) The descent amount reference value K used to determine whether or not arc has occurred is the difference between the previous value Sb and the current value Sn, and the arc determination threshold value is a predetermined ratio (1- Multiply by the arc descent rate a). Therefore, the arc determination threshold value and the descent amount reference value K can be easily obtained.
[0053]
(7) The arc descent rate a used for setting the arc determination threshold value and the descent amount reference value K is 0.15. Therefore, it is possible to determine the occurrence of the arc with a margin from the degree of the current value drop immediately after the occurrence of the arc.
[0054]
(8) The detection unit 15 is a fuse. Therefore, when either IC 17 or FET 13 does not operate normally, the detection unit 15 is melted and the circuit is shut off at the time of dead short in which a large current continuously flows.
[0055]
In addition, embodiment is not limited to the said embodiment, For example, you may change as follows.
○ The forced off time T is not limited to 1.8 ms, and may be a time sufficient to reliably extinguish the arc (at least 1.0 ms) that does not affect the behavior of the load. You may change suitably by change of the magnitude | size etc. of a steady current.
[0056]
○ The arc descent amount reference value K may be increased as the sampling interval is longer, and may be decreased as the sampling interval is shorter. For example, the reference value K may be set in proportion to the sampling interval. For example, when the sampling interval is 0.4 ms, the reference value K is the previous value Sb × 0.30.
[0057]
The condition for switching the FET 13 to the OFF state is not limited to the previous value Sb−current value Sn> drop amount reference value K. For example, a predetermined range below the steady current value may be provided, and the determination unit 31 may be configured to turn off the FET 13 and extinguish the arc when the detected current value S enters this predetermined range. . In this configuration, when the current value S falls below the steady current, such as when the connector 28 is detached, the current value S enters this predetermined range and is switched off, so that the arc can be extinguished also in this configuration.
[0058]
The detection unit 15 is not limited to a fuse, and may be any device that can output in proportion to a current value, such as a current sensor using a shunt resistor, a thermistor, a Hall element, an LSI, or the like.
[0059]
The switch means is not limited to the FET 13 and may be any other semiconductor relay or the like that can turn on / off the circuit by a signal.
The IC 17 is not limited to the configuration including the determination unit 31, the operational amplifier 32, and the driver circuit 33. Further, the control means is not limited to a microcomputer, and may be another arithmetic processing device, for example.
[0060]
The power supply voltage of the automobile electric circuit in which the present invention is implemented is not limited to 42 V, and may be applied to a vehicle including a 14 V power supply circuit, for example.
The present invention may be applied to other than automobile electric circuits.
[0061]
The invention (technical idea) that can be grasped from each of the above embodiments will be additionally described below.
(1) in front The detecting means is configured to detect a current value at a predetermined sampling interval, and the control means is configured such that a difference between a detected current value at the previous sampling time and a detected current value at the current sampling time is a predetermined reference value for a descent amount during arcing. When it becomes larger than the above, the switch means is driven to switch in the OFF direction.
[0062]
(2) in front The detecting means is configured to detect a current value at a predetermined sampling interval, and the arc determination threshold is set in proportion to the sampling interval.
[0063]
【The invention's effect】
As detailed above, claims 1 to claim 8 According to the invention described in (1), when an arc occurs in the electric circuit, the arc can be extinguished instantaneously, and the adverse effect of the arc on the electric circuit can be minimized.
[Brief description of the drawings]
FIG. 1A is a perspective view showing a schematic configuration of an arc reduction device according to an embodiment, and FIG. 1B is an electric circuit diagram in an automobile.
FIG. 2 is a flowchart showing an arc reduction control processing routine.
3A is a graph of a current flowing through a load, and FIG. 3B is a graph of a circuit control signal.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 13 ... FET as switch means, 15 ... Detection part which comprises detection means, 29 ... Electric load, 32 ... Operational amplifier which comprises detection means, 31 ... Judgment part as control means, B ... Battery as power supply, F ... Arc reduction device, T: Forced off time as off time.

Claims (8)

The current value of the current flowing from the power source of the electric circuit to the electric load is detected, and when the detected current value satisfies a predetermined condition that is a current value condition at the time of arc occurrence, the electric circuit is forcibly cut off and the arc is An arc reduction method for forcibly extinguishing
As the predetermined condition, when the detected current value becomes less than a predetermined arc determination threshold value, the electric circuit is forcibly cut off, and the detected current value is detected at a predetermined sampling interval, The arc reduction method in which the threshold value is set to a value obtained by multiplying the detected current value at the previous sampling by a predetermined ratio . 2. The arc reduction method according to claim 1, wherein the sampling interval is set to an interval shorter than a time required for extinguishing the arc when an arc occurs in the electric circuit . After forcibly cut off before Symbol electrical circuit, after a lapse of time required for extinguishing the arc, forced interruption of the electric circuit so that the current supply state to the electric load is turned on from the power supply The arc reduction method according to claim 1 or 2, wherein the state is released. The off-time electrical circuit is to be forcibly cut off, the claim 2 or claim 3 arc is reliably set to a time small that does not affect the behavior of the arc extinction vital said electric load Arc reduction method. Switch means for switching on and off the current supply state from the power supply of the electric circuit to the electric load, detection means for detecting the current value of the current flowing from the power supply to the electric load, and the detected current value by the detection means when the arc is generated Control means for switching and driving the switch means so that the current supply state is turned off when a predetermined condition that is a current value condition is satisfied,
The control means drives the switch means to switch in the OFF direction when the detection current value by the detection means becomes less than a predetermined arc determination threshold, and the detection means detects a current value at a predetermined sampling interval. The arc reduction device configured as described above, wherein the arc determination threshold is set to a value obtained by multiplying a detection current value at the time of previous sampling by the detection means by a predetermined ratio . 6. The arc reducing device according to claim 5, wherein the sampling interval by the detecting means is set to be shorter than the time required for extinguishing the arc when an arc occurs in the electric circuit . The control means is configured so that the current supply state is turned on after the time required for arc extinction has elapsed after the switch means is switched and driven so that the current supply state is turned off. The arc reduction device according to claim 6, wherein the switch means is switched and driven . The off-time electrical circuit is to be forcibly cut off, the claim 6 or claim 7 arc is reliably set to a time small that does not affect the behavior of the arc extinction vital said electric load Arc reduction device.

Images