JP2015122203A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit breaker which is hardly affected by electromagnetic wave noise regardless of the length of wiring.SOLUTION: A processing circuit 4 is electrically connected to one end of a current transformer 3 via first wiring 71 and is electrically connected to the other end of the current transformer 3 via second wiring 72. An interruption unit 5 interrupts a current flowing through an electric path 2 upon receiving output of the processing circuit 4. A first resistor 61 is inserted between the first wiring 71 and the second wiring 72 to form a path through which a secondary current of the current transformer 3 flows. A detection unit 41 detects a potential difference between the first wiring 71 and the second wiring 72. A determination unit 42 determines whether or not to operate the interruption unit 5 on the basis of the potential difference detected by the detection unit 41.

Description

  The present invention relates generally to circuit breakers, and more particularly to circuit breakers using current transformers.

  2. Description of the Related Art Conventionally, there has been provided a circuit breaker that monitors a current flowing through an electric circuit using a current transformer and interrupts the electric circuit when an abnormal current flows. As this type of circuit breaker, for example, a circuit breaker for detecting an overcurrent or a short-circuit current with a current transformer (CT), or a circuit breaker for detecting an abnormal current that flows when a current leaks with a zero phase current transformer (ZCT) Etc. are known.

  For example, Patent Document 1 discloses a current transformer (zero-phase current transformer: ZCT), a leakage detection unit that detects the presence or absence of a ground fault based on the output of the current transformer, and a detection operation of the leakage detection unit. An earth leakage circuit breaker having an electromagnetic coil for operating the breaker is described. In the earth leakage breaker described in Patent Document 1, the earth leakage detection unit has an earth leakage determination circuit as a semiconductor IC, and the electric current between the earth leakage determination circuit and the current transformer (ZCT) is electrically connected via a pair of wires. It is connected to the.

  In this type of circuit breaker, if there is external electromagnetic noise, the circuit acts as an antenna and a high-frequency current is induced in the circuit, so the breaker is activated even though no ground fault has actually occurred. This may lead to malfunction of the leakage detection circuit. Therefore, in the earth leakage circuit breaker described in Patent Document 1, with respect to each wiring, starting from the end portion on the current transformer side or the earth leakage determination circuit side, the position is divided into less than a quarter wavelength of the assumed electromagnetic wave noise. One end of each capacitor is connected. The other end of the capacitor is connected to the ground. For example, when the frequency of electromagnetic noise is 1 GHz (1/4 wavelength is 75 mm), a capacitor is connected at a position where each wiring is divided by less than 75 mm.

  Thereby, in the earth leakage breaker described in Patent Document 1, since the high-frequency current induced in the wiring flows to the ground through the capacitor, the wiring is divided into two around the capacitor in terms of high frequency. Since the length of each divided wiring is less than a quarter wavelength of electromagnetic noise, the resonance phenomenon is suppressed and the high-frequency current does not increase. Therefore, in the configuration described in Patent Document 1, the leakage detection circuit Malfunction is prevented.

Japanese Patent No. 3875167

  By the way, in the configuration in which the influence of electromagnetic wave noise is reduced by the length of the wiring as described in Patent Document 1, when electromagnetic wave noise in a frequency band higher than 1 GHz is assumed, each wiring is arranged at an interval narrower than 75 mm described above. It is necessary to connect a capacitor at the position to be separated. However, considering the physical interference between components, the position where the capacitor can be connected on the wiring is limited, so that the desired wiring length cannot be realized for electromagnetic noise in a very high frequency band. is there. As a result, in the circuit breaker having the above-described configuration, depending on the frequency band of electromagnetic wave noise, the influence of electromagnetic wave noise cannot be reduced, and sufficient radiation immunity may not be realized.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a circuit breaker that is hardly affected by electromagnetic noise regardless of the length of wiring.

  A circuit breaker according to a first aspect of the present invention includes at least one electric circuit, a current transformer that generates a secondary current having a magnitude corresponding to the primary current flowing through the electric circuit, and a first current transformer at one end of the current transformer. A processing circuit electrically connected via the first wiring and electrically connected to the other end of the current transformer via the second wiring, and receives the output of the processing circuit and flows to the electric circuit And a first resistor that is inserted between the first wiring and the second wiring and forms a path through which the secondary current flows, and the processing circuit includes: A detection unit that detects a potential difference between the first wiring and the second wiring; and a determination unit that determines whether or not to operate the blocking unit based on the potential difference detected by the detection unit. It is characterized by having.

  A circuit breaker according to a second aspect is the circuit breaker according to the first aspect, further comprising a low-pass filter that is inserted between the first resistor and the processing circuit and passes a signal component having a frequency equal to or lower than a predetermined cutoff frequency. It is characterized by providing.

  A circuit breaker according to a third aspect is the circuit breaker according to the second aspect, wherein the low-pass filter includes a first capacitor inserted between the first wiring and a reference potential point, and the second wiring. And a second capacitor inserted between the reference potential point.

  The circuit breaker according to a fourth aspect is the circuit breaker according to the second aspect, wherein the low-pass filter has a third capacitor inserted between the first wiring and the second wiring. And

  A circuit breaker according to a fifth aspect is the circuit breaker according to the third aspect, wherein the low-pass filter is a second inserted between the first resistor and the first capacitor on the first wiring. And a third resistor inserted between the first resistor and the second capacitor on the second wiring.

  A circuit breaker according to a sixth aspect is the circuit breaker according to the fourth aspect, wherein the low-pass filter is a fourth inserted between the first resistor and the third capacitor on the first wiring. And a fifth resistor inserted between the first resistor and the third capacitor on the second wiring.

  A circuit breaker according to a seventh aspect is the circuit breaker according to the second to sixth aspects, wherein the first wiring and the second wiring both have a wiring length from the low-pass filter to the processing circuit. The wiring length from the filter to the first resistor is shorter than that of the first resistor.

  The circuit breaker according to an eighth aspect is the circuit breaker according to the second to seventh aspects, wherein the low-pass filter is configured in a plurality of stages by a plurality of filter circuits having different cut-off frequencies, and the plurality of filter circuits are The filter circuit having a higher cut-off frequency is arranged so that the wiring length to the processing circuit is shorter.

  In the present invention, the processing circuit determines a detection unit that detects a potential difference between the first wiring and the second wiring, and whether or not to operate the blocking unit based on the potential difference detected by the detection unit. Since it has a determination unit, there is an advantage that it is hardly affected by electromagnetic noise regardless of the length of the wiring.

It is a circuit diagram which shows schematic structure of the circuit breaker which concerns on Embodiment 1. FIG. It is a circuit diagram which shows schematic structure of the circuit breaker which concerns on Embodiment 1. FIG. It is a circuit diagram which shows schematic structure of the circuit breaker which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the structural example 1 of the circuit breaker which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the structural example 2 of the circuit breaker which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the structural example 3 of the circuit breaker which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the structural example 4 of the circuit breaker which concerns on Embodiment 2. FIG. It is a circuit diagram which shows the modification of the circuit breaker concerning Embodiment 2.

(Embodiment 1)
As shown in FIG. 1, the circuit breaker 1 according to the present embodiment includes at least one electric circuit 2, a current transformer 3, a processing circuit 4, a circuit breaker 5, and a first resistor 61. . The current transformer 3 generates a secondary current having a magnitude corresponding to the primary current flowing through the electric circuit 2. The processing circuit 4 is electrically connected to one end of the current transformer 3 via a first wiring 71 and electrically connected to the other end of the current transformer 3 via a second wiring 72. . The interruption unit 5 receives the output of the processing circuit 4 and interrupts the current flowing through the electric circuit 2. The first resistor 61 is inserted between the first wiring 71 and the second wiring 72 and forms a path through which the secondary current flows.

  The processing circuit 4 includes a detection unit 41 and a determination unit 42. The detection unit 41 detects a potential difference between the first wiring 71 and the second wiring 72. The determination unit 42 determines whether to activate the blocking unit 5 based on the potential difference detected by the detection unit 41.

  That is, the circuit breaker 1 according to the present embodiment has a first resistance between a pair of wires (first wire 71 and second wire 72) connected to the current transformer 3, as shown in FIG. The configuration in which 61 is electrically connected is adopted. In this circuit breaker 1, the processing circuit 4 is electrically connected to the current transformer 3 via a pair of wires, and a potential difference between the pair of wires is detected by the detection unit 41, and according to the potential difference. It is comprised so that the interruption | blocking part 5 may be operated.

  In the present embodiment, as an example of the circuit breaker 1, an earth leakage circuit breaker that detects an abnormal current that flows at the time of electric leakage and interrupts the electric circuit 2 is illustrated. The circuit breaker 1 composed of an earth leakage circuit breaker uses a zero-phase current transformer (ZCT) as the current transformer 3, and as shown in FIG. 1, a plurality of (here, three) electric circuits as primary conductors of the current transformer 3. 21, 22 and 23. More specifically, the current transformer 3 is configured by winding a secondary winding 32 around a core 31 formed in an annular shape from a ferromagnetic material. The plurality of electrical paths 21, 22, and 23 as primary conductors are routed so as to pass through the hollow portion inside the core 31.

  Further, contacts 51, 52, and 53 are inserted into the plurality of electric circuits 21, 22, and 23, respectively. Each of the contacts 51, 52, and 53 constitutes a blocking unit 5 together with a series circuit of an electromagnetic coil 54 and a thyristor 55 that are electrically connected between the electric paths 21 and 23. The control terminal (gate terminal) of the thyristor 55 is electrically connected to the output terminal of the processing circuit 4. When the thyristor 55 is turned on in response to the cutoff signal output from the processing circuit 4, the cutoff unit 5 operates so as to open the plurality of contacts 51, 52, 53 by exemplifying the electromagnetic coil 54.

  The circuit breaker 1 as an earth leakage circuit breaker configured in this way is inserted into the distribution path in a three-phase three-wire distribution system that supplies three-phase AC power using a three-wire distribution path, It functions to cut off the power supply when it occurs. That is, the circuit breaker 1 causes the secondary winding 32 to become secondary when an unbalance occurs between the currents flowing through the plurality of electric paths 21, 22, and 23 that penetrate the core 31 of the current transformer 3 due to the occurrence of a ground fault. Since a current flows, the secondary current is detected by the processing circuit 4 so as to operate the blocking unit 5. Here, the magnitude (current value) of the secondary current generated in the secondary winding 32 is determined according to the primary current flowing through the plurality of electric circuits 21, 22, and 23 as the primary conductor.

  Hereinafter, the circuit breaker 1 according to the present embodiment will be described in detail with reference to FIG. However, the configuration described below is only an example of the present invention, and the present invention is not limited to the following embodiment, and the technical idea according to the present invention is not deviated from other embodiments. Within the range, various changes can be made according to the design and the like. In FIG. 2, only one electric circuit 2 is shown as a primary conductor to which the current transformer 3 is attached. However, in the case of a leakage breaker, a plurality of electric circuits 21, 22, and 23 are actually used as the primary conductor.

  In the circuit breaker 1, the first wiring 71 is electrically connected to one end of the secondary winding 32 (see FIG. 1) of the current transformer 3, and the second wiring 72 is the secondary winding of the current transformer 3. The other end of 32 is electrically connected. In the circuit breaker 1, the first resistor 61 is electrically connected between the first wiring 71 and the second wiring 72, as shown in FIG. 2, and thus the secondary winding 32 of the current transformer 3. When a secondary current is generated in the first and second wirings 72, a potential difference is generated between the first wiring 71 and the second wiring 72. That is, since the secondary current induced in the secondary winding 32 flows through the first wiring 71, the first resistor 61, and the second wiring 72, the voltage drop in the first resistor 61 causes the first current to flow. A potential difference is generated between the second wiring 71 and the second wiring 72.

  Therefore, in the circuit breaker 1 according to the present embodiment, as described above, the processing circuit 4 detects the potential difference between the first wiring 71 and the second wiring 72, and the detected potential difference. And a determination unit 42 that operates the blocking unit 5. Here, the detection unit 41 is composed of a differential amplifier circuit using an operational amplifier (operational amplifier), and a voltage corresponding to the difference between the potential of the first wiring 71 and the potential of the second wiring 72, specifically, a potential difference. Is amplified with a predetermined gain. However, the detection unit 41 is not limited to a differential amplifier circuit using an operational amplifier, and may have other configurations.

  The determination unit 42 receives the voltage value output from the detection unit 41 as an input value, and compares this input value with a predetermined threshold value. Specifically, the determination unit 42 includes a comparator, and is configured to output a drive signal to the blocking unit 5 when an input value from the detection unit 41 exceeds a threshold value. As a result, the processing circuit 4 causes an abnormal current to flow through the electric circuit 2 to generate a secondary current, causing a potential difference between the first wiring 71 and the second wiring 72 and the input value of the determination unit 42 exceeding the threshold value. Then, a drive signal is output to the blocking unit 5 to operate the blocking unit 5.

  The circuit breaker 1 of this embodiment includes an electric circuit 2, a current transformer 3, a processing circuit 4, a circuit breaker 5, a first resistor 61, a first wiring 71, and a second wiring 72, all in one housing (see FIG. (Not shown). Further, in the present embodiment, the processing circuit 4 is configured by a dedicated ASIC (Application Specific Integrated Circuit). The processing circuit 4 made of ASIC is mounted on a circuit board (not shown) housed in the housing together with the first resistor 61 and the thyristor 55 (see FIG. 1) of the blocking unit 5. Therefore, the first wiring 71 and the second wiring 72 include a conductive pattern on the circuit board in addition to the electric wire, cable, and lead terminal connected to the secondary winding of the current transformer 3. The processing circuit 4 is connected to the power supply voltage point 91 and the circuit ground 92, and operates by receiving power supply from the power supply voltage point 91-circuit ground 92.

  According to the circuit breaker 1 of the present embodiment described above, since the electric circuit 2 is interrupted according to the potential difference generated between the first wiring 71 and the second wiring 72, the influence of external electromagnetic noise is reduced. Relatively high radiation immunity can be realized. That is, extraneous electromagnetic noise usually acts in the same way on the first wiring 71 and the second wiring 72, and therefore hardly appears as a potential difference between the first wiring 71 and the second wiring 72. In the circuit breaker 1 of this embodiment, the processing circuit 4 operates the circuit breaker 5 based on the potential difference between the first wiring 71 and the second wiring 72 detected by the detection unit 41. There is an advantage that it is not easily affected by electromagnetic noise and malfunction is unlikely to occur.

  In other words, the circuit breaker 1 according to the present embodiment removes common mode noise on the first wiring 71 and the second wiring 72 in the processing circuit 4, and the first wiring 71 and the second wiring 72. Only the differential mode signal above is extracted. Therefore, even if a high frequency current is induced in the first wiring 71 and the second wiring 72 by electromagnetic wave noise, this high frequency current is common mode noise and is therefore removed by the processing circuit 4. Therefore, the circuit breaker 1 according to the present embodiment has an advantage that it is hardly affected by electromagnetic noise regardless of the length of the wiring.

  As a result, even when electromagnetic wave noise in a relatively high frequency band is assumed, the circuit breaker 1 can reduce the influence of the electromagnetic wave noise and can realize sufficient radiation immunity. For example, “IEC60947-2” has provisions for radiation immunity of 80 MHz to 2.7 GHz for earth leakage circuit breakers, but circuit breaker 1 is resistant to electromagnetic noise of 2.7 GHz (1/4 wavelength is about 27 mm). However, sufficient radiation immunity can be realized.

  In particular, in the circuit breaker 1 using a zero-phase current transformer (ZCT) such as an earth leakage circuit breaker, it is necessary to detect a weak secondary current induced by the primary current flowing through the electric circuit 2, so that it is relatively high. Radiation immunity is required. Since the circuit breaker 1 of this embodiment can implement | achieve sufficiently high radiation immunity also with respect to the electromagnetic wave noise of a comparatively high frequency band as mentioned above, it is especially useful for uses, such as an earth leakage circuit breaker.

  However, the configuration of the circuit breaker 1 according to the present embodiment is not limited to the leakage breaker as described above, but can be applied to any circuit breaker using a current transformer. Is possible. The circuit breaker for wiring detects an overcurrent or a short circuit current as an abnormal current with a current transformer (CT), and interrupts the electric circuit. In this case, one electric circuit 2 as a primary conductor is routed so as to penetrate the hollow portion inside the core 31 of the current transformer 3. The circuit breaker 1 as a circuit breaker for wiring processes the secondary current flowing in the secondary winding 32 of the current transformer 3 at that time when an abnormal current (overcurrent or short circuit current) flows in the primary conductor (electric circuit 2). It detects by the circuit 4 and operates so as to activate the blocking part 5.

(Embodiment 2)
As shown in FIG. 3, the circuit breaker 1 according to the present embodiment further includes a low-pass filter 8 that is inserted between the first resistor 61 and the processing circuit 4 and passes a signal component having a predetermined cutoff frequency or less. It differs from the circuit breaker 1 of Embodiment 1 in the point provided. Hereinafter, the same configurations as those of the first embodiment are denoted by common reference numerals, and description thereof is omitted as appropriate. 3-8, only one electric circuit 2 is shown as a primary conductor to which the current transformer 3 is attached. However, in the case of a leakage breaker, a plurality of electric circuits 21, 22, and 23 are actually used as the primary conductor. .

  That is, in the circuit breaker 1 of the present embodiment, the first resistor 61 is electrically connected to the low-pass filter 8 via the first wiring 71 and the second wiring 72. The low-pass filter 8 functions to pass a signal component below the cutoff frequency and reduce (cut off) a noise component having a frequency higher than the cutoff frequency. The output of the low-pass filter 8 is electrically connected to the processing circuit 4 via the first wiring 71 and the second wiring 72. In the present embodiment, the low-pass filter 8 is mounted on the same circuit board as the first resistor 61 and the processing circuit 4. Therefore, the first wiring 71 and the second wiring 72 between the first resistor 61 and the low-pass filter 8 and between the low-pass filter 8 and the processing circuit 4 are configured by conductor patterns on the circuit board.

  According to this configuration, the circuit breaker 1 can remove the differential mode noise on the first wiring 71 and the second wiring 72 by the low-pass filter 8. In other words, the circuit breaker 1 reflects against electromagnetic wave noise that is out of balance between the first wiring 71 and the second wiring 72 by reflecting, for example, a metal part inside a housing (not shown). A relatively high radiation immunity can be realized.

  In short, in the circuit breaker 1 according to the present embodiment, the detection unit 41 detects the potential difference between the first wiring 71 and the second wiring 72 and operates the blocking unit 5 to reduce common mode noise. In addition, the low-pass filter 8 reduces the differential mode noise. In other words, the circuit breaker 1 can achieve double noise removal by the low-pass filter 8 serving as the first noise reduction unit and the detection unit 41 serving as the second noise reduction unit, and can achieve higher radiation immunity. Can be realized.

  Further, in the circuit breaker 1 of the present embodiment, the first wiring 71 and the second wiring 72 both have a wiring length from the low-pass filter 8 to the processing circuit 4 from the low-pass filter 8 to the first resistor 61. It is desirable that the length is shorter than the wiring length. That is, as shown in FIG. 3, in the first wiring 71 and the second wiring 72, the wiring length between the first resistor 61 and the low-pass filter 8 is “L1”, and the wiring between the low-pass filter 8 and the processing circuit 4. If the length is “L2”, the wiring length is preferably L1> L2.

  In this case, the low-pass filter 8 is closer to the processing circuit 4 than the first resistor 61. Therefore, the circuit breaker 1 can suppress the influence of electromagnetic noise on the portion between the low-pass filter 8 and the processing circuit 4 in the first wiring 71 and the second wiring 72, and as a result, the radiation immunity increases. . In order to shorten the wiring length between the low-pass filter 8 and the processing circuit 4, the low-pass filter 8 is preferably arranged as close as possible to the processing circuit 4.

  Here, the low-pass filter 8 serving as the first noise reduction unit can obtain a noise reduction effect at the detection unit 41 serving as the second noise reduction unit when the distance from the processing circuit 4 is obtained, and the external electromagnetic noise. It is more desirable to set so as not to resonate. Specifically, the wiring length between the low-pass filter 8 and the processing circuit 4 is set to a quarter wavelength or more of the assumed electromagnetic wave noise, and the detection unit 41 realizes a noise reduction rate that does not resonate due to the electromagnetic wave noise. . Thereby, the circuit breaker 1 can implement | achieve high radiation immunity also with respect to electromagnetic wave noise of a comparatively high frequency band, irrespective of the distance of the low-pass filter 8 and the processing circuit 4. FIG.

  By the way, the circuit breaker 1 of this embodiment specifically employs a circuit configuration such as configuration examples 1 to 4 described below.

<Configuration example 1>
In this configuration example, as shown in FIG. 4, the low-pass filter 8 includes a first capacitor 81 inserted between the first wiring 71 and the reference potential point 9, a second wiring 72, and a reference potential point. 9 and a second capacitor 82 inserted between them. The reference potential point 9 is a point having a constant potential. Specifically, the reference potential point 9 is the power supply voltage point 91 or the circuit ground 92.

  In other words, the first capacitor 81 has one end electrically connected to the first wiring 71 and the other end connected to the circuit ground 92 that is the reference potential point 9. A connection point between the first wiring 71 and the first capacitor 81 is located between the first resistor 61 and the processing circuit 4.

  The second capacitor 82 has one end electrically connected to the second wiring 72 and the other end connected to a circuit ground 92 that is the reference potential point 9. A connection point between the second wiring 72 and the second capacitor 82 is located between the first resistor 61 and the processing circuit 4.

  According to this configuration example, high-frequency noise (noise component having a frequency higher than the cut-off frequency) on the first wiring 71 can escape to the reference potential point 9 through the first capacitor 81. Similarly, high-frequency noise on the second wiring 72 can be released to the reference potential point 9 through the second capacitor 82. Therefore, the circuit breaker 1 can reduce the influence of high frequency noise on the processing circuit 4 and can enhance the radiation immunity.

<Configuration example 2>
In the present configuration example, the low-pass filter 8 includes a third capacitor 83 inserted between the first wiring 71 and the second wiring 72 as shown in FIG.

  That is, the third capacitor 83 has one end electrically connected to the first wiring 71 and the other end electrically connected to the second wiring 72. A connection point between the first wiring 71 and the third capacitor 83 is located between the first resistor 61 and the processing circuit 4. A connection point between the second wiring 72 and the third capacitor 83 is located between the first resistor 61 and the processing circuit 4.

  According to the present configuration example, the capacitor (third capacitor 83) constituting the low-pass filter 8 is inserted between the first wiring 71 and the second wiring 72, so that the wiring can be easily routed. There is an advantage that it can be realized at low cost.

<Configuration example 3>
In the present configuration example, as shown in FIG. 6, the low-pass filter 8 includes a first capacitor 81 inserted between the first wiring 71 and the reference potential point 9, a second wiring 72, and a reference potential point. 9 and a second capacitor 82 inserted between them. The low-pass filter 8 includes a second resistor 62 inserted between the first resistor 61 and the first capacitor 81 on the first wiring 71, and the first resistor 61 on the second wiring 72. And a third resistor 63 inserted between the second capacitor 82 and the second capacitor 82. The reference potential point 9 is a point having a constant potential. Specifically, the reference potential point 9 is the power supply voltage point 91 or the circuit ground 92.

  That is, the low-pass filter 8 of this configuration example is configured by adding the second resistor 62 and the third resistor 63 to the low-pass filter 8 of the configuration example 1. The second resistor 62 is inserted in the middle of the first wiring 71, one end is electrically connected to the first resistor 61 via the first wiring 71, and the other end is the first wiring 71. Is electrically connected to the first capacitor 81. The third resistor 63 is inserted in the middle of the second wiring 72, one end is electrically connected to the first resistor 61 via the second wiring 72, and the other end is connected to the second wiring 72. Is electrically connected to the second capacitor 82.

  According to this configuration example, since the low-pass filter 8 includes the resistors (the second resistor 62 and the third resistor 63), there is an advantage that high-frequency noise (noise component having a frequency higher than the cutoff frequency) can be further reduced. . Therefore, the circuit breaker 1 can further enhance the radiation immunity.

<Configuration example 4>
In this configuration example, the low-pass filter 8 includes a third capacitor 83 inserted between the first wiring 71 and the second wiring 72 as shown in FIG. The low-pass filter 8 includes a fourth resistor 64 inserted between the first resistor 61 and the third capacitor 83 on the first wiring 71, and the first resistor 61 on the second wiring 72. A fifth resistor 65 inserted between the third capacitor 83 and the third capacitor 83 is further included.

  That is, the low-pass filter 8 of this configuration example is configured by adding the fourth resistor 64 and the fifth resistor 65 to the low-pass filter 8 of the configuration example 2. The fourth resistor 64 is inserted in the middle of the first wiring 71, one end is electrically connected to the first resistor 61 via the first wiring 71, and the other end is the first wiring 71. Is electrically connected to the third capacitor 83. The fifth resistor 65 is inserted in the middle of the second wiring 72, one end is electrically connected to the first resistor 61 via the second wiring 72, and the other end is connected to the second wiring 72. Is electrically connected to the third capacitor 83.

  According to this configuration example, since the low-pass filter 8 includes the resistors (the second resistor 62 and the third resistor 63), there is an advantage that high-frequency noise (noise component having a frequency higher than the cutoff frequency) can be further reduced. . Therefore, the circuit breaker 1 can further enhance the radiation immunity.

  As a modification of the present embodiment, as shown in FIG. 8, the low-pass filter 8 is configured in multiple stages by a plurality of (here, three) filter circuits 801, 802, and 803 having different cutoff frequencies. Also good. In this modification, it is desirable that the plurality of filter circuits 801, 802, and 803 be arranged so that the wire length to the processing circuit 4 becomes shorter as the filter circuit has a higher cutoff frequency.

  In the example of FIG. 8, the low-pass filter 8 includes a first filter circuit 801 for reducing a low frequency (kHz) band, a second filter circuit 802 for reducing a high frequency (MHz band), and a super high frequency (GHz band). ) It has a three-stage configuration with a third filter circuit 803 for band reduction. The cutoff frequency “f1” of the first filter circuit 801, the cutoff frequency “f2” of the second filter circuit 802, and the cutoff frequency “f3” of the third filter circuit 803 are “f1 <f2”. <F3 ”.

  The plurality of filter circuits 801, 802, and 803 are arranged from the first resistor 61 side to the first filter circuit 801 and the second filter circuit so as to remove higher frequency noise components as they approach the processing circuit 4. 802 and the third filter circuit 803 are arranged in this order. The external electromagnetic noise is affected by a shorter wiring length as the frequency becomes higher. However, as in this modification, the filter circuit having a higher cutoff frequency has a shorter wiring length to the processing circuit 4, thereby improving efficiency. There is an advantage that the influence of electromagnetic noise can be reduced. As a result, the circuit breaker 1 is further enhanced in radiation immunity.

  Other configurations and functions are the same as those of the first embodiment.

DESCRIPTION OF SYMBOLS 1 Circuit breaker 2,21,22,23 Electric circuit 3 Current transformer 4 Processing circuit 41 Detection part 42 Determination part 5 Breaking part 61 1st resistance 62 2nd resistance 63 3rd resistance 64 4th resistance 65 5th Resistance 71 first wiring 72 second wiring 8 low-pass filter 81 first capacitor 82 second capacitor 83 third capacitor 801, 802, 803 filter circuit

Claims (8)

At least one electrical circuit;
A current transformer for generating a secondary current having a magnitude corresponding to the primary current flowing through the electric circuit;
A processing circuit electrically connected to one end of the current transformer via a first wiring and electrically connected to the other end of the current transformer via a second wiring;
A blocking unit that receives an output of the processing circuit and blocks a current flowing in the electric circuit;
A first resistor inserted between the first wiring and the second wiring and forming a path through which the secondary current flows;
The processing circuit is
A detector that detects a potential difference between the first wiring and the second wiring;
A circuit breaker comprising: a determination unit that determines whether to activate the circuit breaker based on the potential difference detected by the detection unit. The circuit breaker according to claim 1, further comprising a low-pass filter that is inserted between the first resistor and the processing circuit and allows a signal component having a frequency equal to or lower than a predetermined cutoff frequency to pass therethrough. The low-pass filter is
A first capacitor inserted between the first wiring and a reference potential point;
The circuit breaker according to claim 2, further comprising: a second capacitor inserted between the second wiring and the reference potential point. The low-pass filter is
The circuit breaker according to claim 2, further comprising a third capacitor inserted between the first wiring and the second wiring. The low-pass filter is
A second resistor inserted between the first resistor and the first capacitor on the first wiring;
The circuit breaker according to claim 3, further comprising a third resistor inserted between the first resistor and the second capacitor on the second wiring. The low-pass filter is
A fourth resistor inserted between the first resistor and the third capacitor on the first wiring;
The circuit breaker according to claim 4, further comprising a fifth resistor inserted between the first resistor and the third capacitor on the second wiring. Both the first wiring and the second wiring are configured such that the wiring length from the low-pass filter to the processing circuit is shorter than the wiring length from the low-pass filter to the first resistor. The circuit breaker of any one of Claims 2-6 characterized by these. The low-pass filter is configured in multiple stages with a plurality of filter circuits having different cutoff frequencies,
The plurality of filter circuits are arranged such that a filter circuit having a higher cut-off frequency has a shorter wiring length to the processing circuit. Circuit breaker.

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