Current measuring devices, circuit breakers and distribution boards

Abstract

To provide a current measuring device that can ensure reliability of a current measuring section.SOLUTION: A current measuring device 40 includes a plurality of current measuring sections 27a to 27c and a self-diagnosis determining section 31c. The plurality of current measuring units 27a to 27c measure the current flowing through each of a plurality of electric lines 7a to 7c forming a set of electric lines through which alternating current flows. The self-diagnosis determining section 31c performs a self-diagnosis determination as to whether or not the plurality of current measuring sections 27a to 27c are normal based on the measured values of each of the plurality of current measuring sections 27a to 27c.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a current measurement device, a circuit breaker, and a distribution board. More particularly, the present disclosure relates to a current measurement device that measures AC current, a circuit breaker including the current measurement device, and a distribution board including the circuit breaker. [Background technology]

[0002] The circuit breaker described in Patent Document 1 includes contacts, a switching mechanism, and a tripping device. The contacts are provided in an electric circuit that supplies power from an AC power source to a load, and open and close the electric circuit. The switching mechanism drives the contacts to open and close in response to control from the tripping device. When an abnormal current such as an overcurrent occurs in the electric circuit, the tripping device opens the contacts via the switching mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-062775 Summary of the Invention [Problem to be solved by the invention]

[0004] In the circuit breaker described above, a configuration using a current sensor (current measurement unit) that measures the current flowing through the electrical circuit instead of the trip device is being considered. However, the current sensor has a more complicated configuration than the trip device, but it is necessary to ensure the same level of reliability as the trip device.

[0005] The present disclosure has been made in consideration of the above reasons, and its purpose is to provide a current measuring device that can ensure the reliability of the current measuring unit, a circuit breaker equipped with the current measuring device, and a distribution board equipped with the circuit breaker. [Means for solving the problem]

[0006] A current measurement device according to one aspect of the present disclosure includes a plurality of current measurement units and a self-diagnosis determination unit. Connected to a two-wire circuit To power the load Intersection A set of electrical circuits through which current flows The set of electric circuits branched from the two-wire electric circuit The self-diagnosis determination unit measures the current flowing through each of the plurality of electric paths constituting the power supply. The self-diagnosis determination unit makes a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units. The self-diagnosis determination unit makes the self-diagnosis determination depending on whether the sum of the measurement values ​​measured by the plurality of current measurement units at the same time is zero. A current measurement device according to one aspect of the present disclosure includes a plurality of current measurement units and a self-diagnosis determination unit. The plurality of current measurement units measure the current flowing through each of a plurality of electric paths constituting a set of electric paths through which an AC current flows. The self-diagnosis determination unit performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units. The self-diagnosis determination unit performs the self-diagnosis determination depending on whether a sum of measurement values ​​measured simultaneously by the plurality of current measurement units is zero. The plurality of electric paths is composed of a first voltage line, a second voltage line that is opposite in phase to the first voltage line, and a grounded neutral line. The measurement value of the current flowing through the first voltage line is defined as a first measurement value. The measurement value of the current flowing through the second voltage line is defined as a second measurement value. The measurement value of the current flowing through the neutral line is defined as a third measurement value. The self-diagnosis determination unit performs the self-diagnosis determination depending on whether a sum of the first measurement value, the second measurement value, and the third measurement value is zero. A current measurement device according to one aspect of the present disclosure includes a plurality of current measurement units and a self-diagnosis determination unit. The plurality of current measurement units measure the current flowing through each of a plurality of electric paths constituting a set of electric paths through which an AC current flows. The self-diagnosis determination unit performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units. The plurality of electric paths are composed of a first voltage line, a second voltage line having an opposite phase to the first voltage line, and a grounded neutral line. The effective value of the measurement value of the current flowing through the first voltage line during a predetermined time period is defined as a first effective value. The effective value of the measurement value of the current flowing through the second voltage line during the predetermined time period is defined as a second effective value. The effective value of the measurement value of the current flowing through the neutral line during the predetermined time period is defined as a third effective value. The self-diagnosis determination unit performs the self-diagnosis determination based on whether the absolute value of the difference between the first effective value and the second effective value is equal to the third effective value. A current measurement device according to one aspect of the present disclosure includes a plurality of current measurement units and a self-diagnosis determination unit. The plurality of current measurement units measure the current flowing through each of a plurality of electric paths constituting a set of electric paths through which an AC current flows. The self-diagnosis determination unit performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units. The plurality of electric paths are composed of a first voltage line, a second voltage line having an opposite phase to the first voltage line, and a grounded neutral line. An integral value of the measurement value of the current flowing through the first voltage line over a predetermined time period is defined as a first integral value. An integral value of the measurement value of the current flowing through the second voltage line over the predetermined time period is defined as a second integral value. An integral value of the measurement value of the current flowing through the neutral line over the predetermined time period is defined as a third integral value. The self-diagnosis determination unit performs the self-diagnosis determination based on whether the absolute value of the difference between the first integral value and the second integral value is equal to the third integral value. A current measurement device according to one aspect of the present disclosure includes a plurality of current measurement units, a self-diagnosis determination unit, a zero-phase current transformer, and a leakage current determination unit. The plurality of current measurement units measure the current flowing through each of a plurality of electric paths constituting a set of electric paths through which an AC current flows. The self-diagnosis determination unit performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units. The zero-phase current transformer measures the imbalance of the current flowing through each of the plurality of electric paths. The leakage current determination unit determines whether a leakage current has occurred based on the measurement values ​​of the zero-phase current transformer. If the leakage current determination unit determines that a leakage current has occurred, the self-diagnosis determination unit discards the result of the self-diagnosis determination.

[0007] A circuit breaker according to one aspect of the present disclosure is a circuit breaker including the current measurement device. The circuit breaker includes a plurality of contacts, the current measurement device, an overcurrent determination unit, and a drive control unit. The plurality of contacts open and close a plurality of electrical paths that constitute a set of electrical paths for supplying AC power from an AC power source to one or more loads. The current measurement device includes a plurality of current measurement units that measure currents flowing through the plurality of electrical paths. The overcurrent determination unit determines whether an overcurrent has occurred in the plurality of electrical paths based on the measurement values ​​of each of the plurality of current measurement units. The drive control unit controls a drive unit to open and close the plurality of contacts based on the determination result of the overcurrent determination unit.

[0008] A distribution board according to one aspect of the present disclosure includes the circuit breaker and a cabinet that holds the circuit breaker. [Effects of the Invention]

[0009] The current measuring device, circuit breaker, and distribution board according to the present disclosure have the effect of ensuring the reliability of the current measuring unit. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic configuration diagram of a circuit breaker according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram of a distribution board equipped with the circuit breaker. [Figure 3] FIG. 3 is a perspective view of the circuit breaker. [Figure 4] FIG. 4 is a partially exploded perspective view of the circuit breaker. [Figure 5] FIG. 5 is a current waveform diagram showing the change over time in the current waveform of a current flowing in a single-phase three-wire electrical circuit. [Figure 6] FIG. 6 is a perspective view of a control board of the circuit breaker. DETAILED DESCRIPTION OF THE INVENTION

[0011] (1) Overview The current measuring device 40, the circuit breaker 20, and the distribution board 1 of this embodiment will be described with reference to Figures 1 and 2. In the following description, it is assumed that the current measuring device 40 is provided in the circuit breaker 20, and the circuit breaker 20 is provided in the distribution board 1 as a main breaker 2.

[0012] The current measuring device 40 is a current measuring device with a self-diagnosis function. More specifically, as shown in FIG. 1, the current measuring device 40 includes multiple (e.g., three) current measuring units 27a-27c and a self-diagnosis determination unit 31c. The multiple current measuring units 27a-27b measure the current flowing through each of multiple electric paths 7a-7c that constitute a set of electric paths through which an AC current flows. The self-diagnosis determination unit 31c performs a self-diagnosis determination as to whether the multiple current measuring units 27a-27c are normal based on the measurement values ​​of each of the multiple current measuring units 27a-27c. This configuration ensures the reliability of the multiple current measuring units 27a-27c. More specifically, the self-diagnosis determination unit 31c performs a self-diagnosis determination based on, for example, whether the sum of the measurement values ​​measured by the multiple current measuring units 27a-27c at the same time is zero. This configuration enables the self-diagnosis determination to be performed using a simple determination principle.

[0013] 1, the circuit breaker 20 is a main breaker 2 provided in a distribution board 1 for distributing AC power from an AC power source P1 (for example, a system power source) to one or more loads B1 in a building. When an overcurrent flows through a plurality of electric circuits 7a to 7c, the circuit breaker 20 detects the overcurrent and cuts off the plurality of electric circuits 7a to 7c to stop the power supply to the load B1.

[0014] The circuit breaker 20 includes a plurality of contacts C1, a current measuring device 40, an overcurrent determination unit 31b, and a drive control unit 31d. The plurality of contacts C1 open and close the plurality of electric circuits 7a to 7c. As described above, the current measuring device 40 includes a plurality of current measuring units 27a to 27c and a self-diagnosis determination unit 31c. The overcurrent determination unit 31b determines whether an overcurrent has occurred in the plurality of electric circuits 7a to 7c based on the measurement values ​​of each of the plurality of current measuring units 27a to 27c. The drive control unit 31d opens and closes the plurality of contacts C1 via the drive unit 26 based on the determination result of the overcurrent determination unit 31b. With this configuration, a circuit breaker having the same functions and effects as the current measuring device 40 can be provided as the circuit breaker 20.

[0015] 2, the distribution board 1 includes a circuit breaker 20 (main breaker 2) and a cabinet 10 that holds the circuit breaker 20. With this configuration, it is possible to provide a distribution board 1 that has the same functions and effects as the circuit breaker 20.

[0016] (2) Detailed configuration The current measuring device 40, circuit breaker 20, and distribution board 1 of this embodiment will be described in more detail below with reference to Figures 1 to 6. In the following description, unless otherwise specified, the front, back, top, bottom, left, and right of the current measuring device 40, circuit breaker 20, and distribution board 1 will be defined by the directions of imaginary arrows shown in Figures 2 and 3. However, defining these directions is not intended to limit the manner in which the circuit breaker 20 and distribution board 1 can be used.

[0017] (2.1) Distribution board As shown in FIG. 2, the distribution board 1 includes a main breaker 2 (circuit breaker 20), a plurality of branch breakers 3, and a cabinet 10 that houses these.

[0018] In this embodiment, the distribution board 1 is installed in a detached house as an example of a building, but the example is not limited to this. The distribution board 1 may be installed in any facility where it can be installed, such as each dwelling unit in an apartment building, an office, a store, a factory, a hospital, or the like.

[0019] The distribution board 1 receives AC power from an AC power source P1 (e.g., a grid power source) and distributes the received AC power to one or more loads B1 within a building. At this time, the distribution system of the AC power from the AC power source P1 is converted to a single-phase three-wire distribution system by a pole transformer T1. Therefore, the distribution board 1 receives AC power from the AC power source P1 via single-phase three-wire electric circuits 7a-7b. The distribution system of the AC power from the AC power source P1 is also converted from the single-phase three-wire system to a two-wire system within the distribution board 1. As a result, power is supplied from the distribution board 1 to each load B1 via two-wire electric circuits 11a, 11b. That is, in this embodiment, a plurality of sets of two-wire electric circuits 11a, 11b branch off from the single-phase three-wire electric circuits 7a-7c, and power is supplied from the distribution board 1 to one or more loads B1 via these plurality of two-wire electric circuits 11a, 11b.

[0020] The electric circuits 7a to 7c are the L1-phase electric circuit 7a (first voltage line), the L2-phase electric circuit 7b (second voltage line), and the N-phase electric circuit 7c (neutral line), respectively. Currents of opposite phases flow through the L1-phase electric circuit 7a and the L2-phase electric circuit 7b. The N-phase electric circuit 7c is grounded. In this embodiment, the L1-phase electric circuit 7a includes a lead-in wire 8a, a conductive bar 9a, and a connection wire 24a, which will be described later. The L2-phase electric circuit 7b includes a lead-in wire 8b, a conductive bar 9b, and a connection wire 24b, which will be described later. The N-phase electric circuit 8c includes a lead-in wire 8c, a conductive bar 9c, and a connection wire 24c, which will be described later.

[0021] The load B1 is, for example, a device such as a lighting fixture, an air conditioner, a television receiver, or a hot water supply system, or a wiring device such as a wall switch.

[0022] The main breaker 2 is disposed inside the cabinet 10. The main breaker 2 is connected to the above-mentioned single-phase three-wire electric circuits 7a to 7c. The main breaker 2 includes primary side terminals 21a to 21c and secondary side terminals 22a to 22c. Since the distribution board 1 of this embodiment assumes a single-phase three-wire system as the power distribution method, single-phase three-wire service lines 8a to 8c on the AC power source P1 side are electrically connected to the primary side terminals 21a to 21c of the main breaker 2. Furthermore, conductive bars 9a to 9c are connected to the secondary side terminals 22a to 22c of the main breaker 2.

[0023] Details of the main breaker 2 will be explained in the section "(2.2) Main breaker and current measuring device."

[0024] 2, the branch breakers 3 are connected to the plurality of pairs of two-wire electric circuits 11a, 11b. When an abnormal current (overcurrent or leakage current) flows in the electric circuit 11a, 11b to which the branch breakers 3 are connected, the plurality of branch breakers 3 detects the abnormal current and cuts off the electric circuit 11a, 11b to stop the power supply to the load B1.

[0025] The branch breakers 3 are arranged side by side in the left-right direction, above and below the conductive bars 9a-9c. The branch breakers 3 are available for 100V and 200V. The 100V branch breakers 3 are connected to the electric circuits 11a, 11b connected to one of the L1-phase conductive bars 9a and the L2-phase conductive bar 9b and the N-phase conductive bar 9c, among the multiple sets of two-wire electric circuits 11a, 11b. The 200V branch breakers 3 are connected to the electric circuits 11a, 11b connected to the L1-phase conductive bar 9a and the L2-phase conductive bar 9b, among the multiple sets of two-wire electric circuits 11a, 11b.

[0026] (2.2) Main breaker and current measuring device Next, the main breaker 2 (circuit breaker 20) and the current measuring device 40 of this embodiment will be described with reference to FIGS. 1 and 3 to 5. FIG.

[0027] As shown in Figures 1, 3 and 4, the main breaker 2 includes a plurality of primary side terminals 21a to 21c, a plurality of secondary side terminals 22a to 22c, a plurality of contact mechanisms 23a to 23c, a plurality of connection wires 24a to 24c, an operating lever 25, a drive unit 26, a plurality of current measuring units 27a to 27a, a zero-phase current transformer 28, an alarm unit 29, a power supply circuit 30, a processing unit 31, a control board 32, a power supply board 33, and a case 34 that houses these.

[0028] In this embodiment, of the above components of the main breaker 2, at least the multiple current measurement units 27a to 27c and a self-diagnosis determination unit 31c (described later) of the processing unit 31 constitute a current measurement device 40. That is, of the above components of the main breaker 2, the current measurement device 40 includes at least the multiple current measurement units 27a to 27c and a self-diagnosis determination unit 31c (described later) of the processing unit 31.

[0029] 3 and 4, the case 34 is formed from synthetic resin in the shape of a hollow rectangular parallelepiped. The case 34 includes a body 34a and a cover 34b. The body 34a is a rectangular parallelepiped box with an open front face. The cover 34b is a rectangular parallelepiped box (e.g., a shallow box) with an open rear face, and is connected to the body 34a so as to cover the front opening of the body 34a.

[0030] The case 34 includes a first terminal mounting portion 34c, a second terminal mounting portion 34d, a lever insertion hole 34e, and a plurality of notification holes 34f.

[0031] The first terminal attachment portion 34c is a portion to which the plurality of primary side terminals 21a to 21c are attached, and is formed in the upper portion of the case 34 from the center to the left end.

[0032] The second terminal attachment portion 34d is a portion to which the multiple secondary side terminals 22a to 22c are attached, and is provided at the right end of the upper end portion of the case 34 so as to protrude upward.

[0033] The lever insertion hole 34e is a portion in which the operating lever 25 is disposed, and is, for example, a rectangular hole. The lever insertion hole 34e is provided, for example, in the front wall of the case 34 (i.e., the front wall of the cover 34b), below the first terminal attachment portion 34c and in the center in the left-right direction.

[0034] The multiple alarm holes 34f are portions in which multiple light-emitting elements 291 (see Figure 6) for notifying various types of information (such as the occurrence of overcurrent or leakage current) are arranged, and are provided on the left side of the lever insertion hole 34e in the front wall of the case 34 (i.e., the front wall of the cover 34b).

[0035] Each of the multiple (e.g., three) primary terminals 21a-21c is a screw terminal equipped with a terminal board 211 and a terminal screw. The multiple primary terminals 21a-21c are arranged side by side in the left-right direction on the front surface of the first terminal mounting portion 34c. Single-phase three-wire service lines 8a-8c extending from the AC power source P1 are electrically connected to the multiple primary terminals 21a-21c. Specifically, the single-phase three-wire L1-phase service line 8a is connected to the left primary terminal 21a, the L2-phase service line 8b is connected to the right primary terminal 21b, and the N-phase service line 8c is connected to the central primary terminal 21c.

[0036] A plurality of (e.g., three) secondary terminals 22a-22c are arranged to protrude from the right side surface of the second terminal mounting portion 34d. Conductive bars 9a-9c are connected to the secondary terminals 22a-22c, respectively, using terminal screws. Specifically, the L1-phase conductive bar 9a is connected to the upper secondary terminal 22a, the L2-phase conductive bar 9b is connected to the lower secondary terminal 22b, and the N-phase conductive bar 9c is connected to the central secondary terminal 22c.

[0037] The primary terminals 21a to 21c and the secondary terminals 22a to 22c are in one-to-one correspondence. The primary terminals 21a to 21c and the secondary terminals 22a to 22c are connected to each other by corresponding connection wires 24a to 24c (FIG. 1). Contact mechanisms 23a to 23c are connected to the connection wires 24a to 24c, respectively (FIG. 1).

[0038] The contact mechanisms 23a to 23c correspond one-to-one to the connection wires 24a to 24c and connect and disconnect the corresponding connection wires 24a to 24c (FIG. 1). Each of the contact mechanisms 23a to 23c includes a fixed contact 231 and a movable contact 232. The movable contact 232 is movable between a closed position and an open position. The closed position is a position where the movable contact 232 is in contact with the fixed contact 231. The open position is a position where the movable contact is separated from the fixed contact 231. When the movable contact 232 is in the closed position, the contact mechanisms 23a to 23c connect the corresponding connection wires 24a to 24c, and when the movable contact 232 is in the open position, the contact mechanisms 23a to 23c disconnect the corresponding connection wires 24a to 24c. The movable contact 232 and the fixed contact 231 form a contact C1 of the main breaker 2 (circuit breaker 20). That is, the connection lines 24a to 24c (ie, the electric circuits 7a to 7c) are connected to the contact points C1.

[0039] The operating lever 25 is made of a molded synthetic resin. The operating lever 25 is arranged so as to be exposed from the case 34 through the lever insertion hole 34e (Fig. 3). The operating lever 25 can rotate up and down around its lower end. The operating lever 25 can rotate between a closed position and an open position. In the closed position, the operating lever 25 is flush with the opening surface of the lever insertion hole 34e. In the open position, the operating lever 25 protrudes from the lever insertion hole 34e. The operating lever 25 is biased by a predetermined spring in a direction from the closed position to the open position.

[0040] The driving unit 26 controls the contact mechanisms 23a to 23c in response to a control signal from the processing unit 31 to open the contacts C1 from a closed state (FIG. 1), thereby interrupting the connection lines 24a to 24c from a conductive state.

[0041] More specifically, the drive unit 26 includes an opening / closing mechanism 261 and an electromagnetic release device 262 (FIG. 1).

[0042] When the contact C1 is closed, the opening / closing mechanism 261 biases the movable contact 232 from the closed position toward the open position by a predetermined spring force, thereby latching the movable contact 232. When the latch is released by the electromagnetic release device 262, the opening / closing mechanism 261 moves the movable contact 232 from the closed position to the open position by the predetermined spring force, thereby opening the contact C1. This breaks the connection lines 24a to 24c. At this time, the operating lever 25 rotates from the closed position to the open position. When the operating lever 25 is moved from the open position to the closed position by operating the operating lever 25, the opening / closing mechanism 261 moves the multiple movable contacts 232 from the open position to the closed position, thereby closing the contact C1. This brings the connection lines 24a to 24c into conduction.

[0043] The electromagnetic release device 262 includes an electromagnet device including a coil, and a plunger that is moved by an electromagnetic force caused by an excitation current flowing through the coil. The electromagnetic release device 262 flows an excitation current through the coil in response to a control signal from the processing unit 31, thereby moving the plunger and unlatching the opening / closing mechanism 261. As a result, the opening / closing mechanism 261 opens the multiple contacts C1 from a closed state, and the connection lines 24a to 24c are interrupted.

[0044] The current measuring units 27a to 27c correspond one-to-one to the connection lines 24a to 24c, are arranged on the corresponding connection lines 24a to 24c (i.e., on the corresponding electric circuits 7a to 7c), and measure the current values ​​of the currents flowing through the corresponding connection lines 24a to 24c (FIG. 1). The current measuring units 27a to 27c are arranged on the corresponding connection lines 24a to 24c, for example, between the contact C1 and the secondary-side terminals 22a to 22c.

[0045] The current measuring units 27a to 27c are, for example, Rogowski coil-type current sensors. More specifically, the current measuring units 27a to 27c each have a coil 271 (FIG. 6). The coil 271 is a coil (for example, an air-core coil) arranged in a circular shape around the connection wires 24a to 24c (i.e., the electrical circuits 7a to 7c) to be measured. In the current measuring units 27a to 27c, a voltage corresponding to the current flowing through the connection wires 24a to 24c to be measured is generated across both ends of the coil 271, and this voltage is output from the coil 271 to the processing unit 31 as a measurement signal. When the processing unit 31 detects an overcurrent based on the measurement signals from the current measuring units 27a to 27c, it causes the contacts C1 to open from a closed state via the driving unit 26. This breaks the connection wires 24a to 24c.

[0046] The zero-phase-sequence current transformer 28 detects whether or not there is a leakage current in each of the connection lines 24a to 24c (i.e., each of the electric circuits 7a to 7c) by detecting an imbalance between the currents flowing through each of the connection lines 24a to 24c (Fig. 1). Note that the "imbalance between the currents" mentioned above means that the sum of the currents at the same time is not zero.

[0047] The zero-phase current transformer 28 includes an annular core (e.g., a toroidal core) and a secondary winding. A plurality of connection wires 24a-24c (i.e., a plurality of electric circuits 7a-7c) pass through a central hole of the annular core as a primary winding. The secondary winding is wound around the annular core, and when an imbalance occurs among the currents flowing through the plurality of connection wires 24a-24c, the secondary winding outputs a voltage corresponding to the imbalance as a measurement signal to the processing unit 31. When the processing unit 31 detects a leakage current based on the measurement signal from the zero-phase current transformer 28, it opens the plurality of contacts C1 from a closed state via the driving unit 26. This breaks the connection wires 24a-24c.

[0048] When the processing unit 31 detects any of various abnormalities (for example, a current leak, an overcurrent, or an abnormality in the current measuring units 27a to 27c), the notification unit 29 notifies people nearby that the abnormality has been detected.

[0049] More specifically, the notification unit 29 includes a plurality of light emitting units 291 and a sound output unit 292 (FIG. 1).

[0050] The light-emitting elements 291 correspond one-to-one to the various abnormalities described above, and when the processing unit 31 detects the occurrence of a corresponding abnormality, they emit light to notify the occurrence of the abnormality. The light-emitting elements 291 are light-emitting sources such as LEDs (Light Emitting Diodes). The light-emitting elements 291 include a light-emitting element that notifies the occurrence of a leakage current in the electric circuits 7a-7c, a light-emitting element that notifies the occurrence of an overcurrent in the electric circuits 7a-7c, and a light-emitting element that notifies the occurrence of an abnormality in the current measuring elements 27a-27c (i.e., the current measuring elements 27a-27c are not normal). The light-emitting elements 291 emit light to notify the occurrence of an abnormality, and do not emit light to notify the absence of an abnormality. The light-emitting elements 291 correspond one-to-one to the notification holes 34f (FIG. 3) of the case 34, and are exposed forward from the corresponding notification holes 34f.

[0051] The sound output unit 292 is, for example, a buzzer device, and when the processing unit 31 detects the occurrence of any of the above-mentioned abnormalities, it outputs a buzzer sound to notify people nearby of the occurrence of the above-mentioned abnormalities. Note that the sound output unit 292 may individually notify the occurrence of any of the above-mentioned abnormalities by a voice message such as "An overcurrent has occurred."

[0052] The power supply circuit 30 generates a power supply voltage for the main breaker 2 (circuit breaker 20) based on the voltage received from two of the plurality of connection lines 24a to 24c (for example, the connection lines 24a and 24c).The power supply circuit 30 then supplies the generated power supply voltage to the processing unit 31, the notification unit 29, the drive unit 26, etc.

[0053] The processing unit 31 detects the above-mentioned various abnormalities (e.g., leakage current, overcurrent, and abnormality of the current measuring units 27a-27c) based on the measurement signals of the multiple current measuring units 27a-27c and the zero-phase current transformer 28. When the processing unit 31 detects the above-mentioned various abnormalities, it opens the multiple contacts C1 from a closed state to cut off the multiple connection lines 24a-24c. This cuts off the power supply from the AC power source P1 to the load B1.

[0054] The processing unit 31 includes a leakage current determining unit 31a, an overcurrent determining unit 31b, a self-diagnosis determining unit 31c, a notification control unit 31e, and a drive control unit 31d.

[0055] The processing unit 31 is configured by an arithmetic device such as a CPU. More specifically, the processing unit 31 is primarily configured as a computer system having one or more processors and one or more memories. In the processing unit 31, the one or more processors execute programs stored in the memory, thereby realizing the respective functions of the processing unit 31 (electric leakage determination unit 31a, overcurrent determination unit 31b, self-diagnosis determination unit 31c, notification control unit 31e, and drive control unit 31d). The programs may be pre-recorded in the memory, provided via a telecommunications line such as the Internet, or provided by being recorded on a non-transitory recording medium such as a memory card.

[0056] The overcurrent determination unit 31b determines whether or not an overcurrent has occurred in the plurality of connection lines 24a to 24c (i.e., the plurality of electrical circuits 7a to 7c) based on the measurement values ​​of each of the plurality of current measurement units 27a to 27c (overcurrent determination). The overcurrent determination unit 31b, for example, periodically performs the overcurrent determination.

[0057] More specifically, the overcurrent determination unit 31b obtains a measurement value (digital value) from the measurement signals (analog values) from the multiple current measurement units 27a to 27c. Then, as an overcurrent determination, the overcurrent determination unit 31b determines whether or not the measurement value of each of the multiple current measurement units 27a to 27c (i.e., the current value of the current flowing through the multiple connection lines 24a to 24c) is equal to or greater than a predetermined threshold. Based on the result of the overcurrent determination, the overcurrent determination unit 31b controls the drive unit 26 to open and close the multiple contacts C1.

[0058] That is, if at least one of the measurement values ​​of the multiple current measuring units 27a to 27c is equal to or greater than a predetermined threshold, the overcurrent determining unit 31b determines that an overcurrent has occurred. In this case, the overcurrent determining unit 31b controls the drive unit 26 to change the multiple contacts C1 from a closed state to an open state. On the other hand, if all of the measurement values ​​of the multiple current measuring units 27a to 27c are less than the predetermined threshold, the overcurrent determining unit 31b determines that an overcurrent has not occurred. In this case, the overcurrent determining unit 31b controls the drive unit 26 to maintain the multiple contacts C1 in a closed state.

[0059] The leakage current determination unit 31a determines whether or not there is leakage in the currents flowing through the plurality of connection lines 24a to 24c (i.e., the plurality of electric circuits 7a to 7c) based on the measurement values ​​of the zero-phase-sequence current transformer 28 (leakage determination), depending on whether or not an imbalance has occurred in the currents flowing through the plurality of connection lines 24a to 24c (i.e., the plurality of electric circuits 7a to 7c). The leakage current determination unit 31a, for example, periodically performs the leakage current determination.

[0060] More specifically, the leakage current determination unit 31a obtains a measurement value (digital value) from the measurement signal (analog value) of the zero-phase-sequence current transformer 28. Then, to determine whether or not there is a leakage current, the leakage current determination unit 31a determines whether or not the measurement value of the zero-phase-sequence current transformer 28 is zero. Note that the above phrase "the measurement value of the zero-phase-sequence current transformer 28 is zero" is not limited to the case where the measurement value is strictly zero, but also includes the case where the measurement value is within a certain range in which it can be considered to be substantially zero.

[0061] The leakage current determination unit 31a controls the driver 26 to open and close the plurality of contacts C1 based on the result of the leakage current determination. More specifically, if the measurement value of the zero-phase-sequence current transformer 28 is zero, the leakage current determination unit 31a determines that an imbalance has occurred in the currents flowing through the plurality of connection lines 24a to 24c (i.e., a leakage current has occurred). In this case, the leakage current determination unit 31a controls the driver 26 to change the plurality of contacts C1 from a closed state to an open state. On the other hand, if the measurement value of the zero-phase-sequence current transformer 28 is not zero, the leakage current determination unit 31a determines that an imbalance has not occurred in the currents flowing through the plurality of connection lines 24a to 24c (i.e., no leakage current has occurred). In this case, the leakage current determination unit 31a controls the driver 26 to maintain the plurality of contacts C1 in a closed state.

[0062] The self-diagnosis determination unit 31c determines whether the current measuring units 27a to 27c are normal or not (self-diagnosis determination) based on the measurement values ​​of each of the current measuring units 27a to 27c. The self-diagnosis determination unit 31c performs self-diagnosis determination depending on whether the sum of the measurement values ​​measured by the current measuring units 27a to 27c at the same time (i.e., instantaneous values ​​at the same time) is zero.

[0063] Specifically, the measurement value measured by the current measurement unit 27a at a predetermined time t1 (i.e., the measurement value of the current Ia flowing through the L1-phase electric circuit 7a at the predetermined time t1) is defined as a first measurement value Ia(t1). The measurement value measured by the current measurement unit 27b at the predetermined time t1 (i.e., the measurement value of the current Ib flowing through the L2-phase electric circuit 7b at the predetermined time t1) is defined as a second measurement value Ib(t1). The measurement value measured by the current measurement unit 27c at the predetermined time t1 (i.e., the measurement value of the current Ic flowing through the N-phase electric circuit 7c at the predetermined time t1) is defined as a third measurement value Ic(t1).

[0064] In this case, the self-diagnosis judgment unit 31c makes a self-diagnosis judgment depending on whether the sum of the first measurement value Ia(t1), the second measurement value Ib(t1), and the third measurement value Ic(t1) is zero (i.e., whether the following equation 1 holds).

[0065] Ia(t1)+Ib(t1)+Ic(t1)=0…Equation 1 That is, if the sum of the three measurement values ​​measured at the same time is zero (that is, if formula 1 is satisfied), the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a to 27c are normal. On the other hand, if the sum of the three measurement values ​​measured at the same time is not zero (that is, if formula 1 is not satisfied), the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a to 27c are not normal (that is, at least one of the multiple current measurement units 27a to 27c is abnormal).

[0066] Note that the above phrase "the sum of the first measurement value Ia(t1), the second measurement value Ib(t1), and the third measurement value Ic(t1) is zero" does not necessarily mean that the sum is strictly zero, but also includes the case where the sum is substantially zero (i.e., the absolute value of the sum is a value equal to or less than a predetermined value that can be regarded as substantially zero).

[0067] That is, when the distribution system of AC power from AC power source P1 is a single-phase three-wire system, there is a characteristic that the sum of the current values ​​of the currents Ia to Ic flowing through the three electric circuits 7a to 7c at the same time (for example, t1) is always zero (i.e., the characteristic that Equation 1 holds) (FIG. 5). Using this characteristic, self-diagnosis determination unit 31c performs self-diagnosis determination of whether the multiple current measurement units 27a to 27c are normal or not, depending on whether the sum of the three measurement values ​​measured at the same time is zero or not.

[0068] The self-diagnosis determination unit 31c discards the result of the self-diagnosis determination depending on the determination result of the leakage current determination unit 31a. More specifically, if the leakage current determination unit 31a determines that no leakage current has occurred in the multiple electric circuits 7a-7c, the self-diagnosis determination unit 31c validates the result of the self-diagnosis determination. On the other hand, if the leakage current determination unit 31a determines that leakage current has occurred in the multiple electric circuits 7a-7c, the self-diagnosis determination unit 31c discards the result of the self-diagnosis determination.

[0069] In other words, when no leakage current is occurring in the multiple electric circuits 7a-7c, the above characteristic (i.e., the above formula 1) holds, and therefore the self-diagnosis determination using the above characteristic can be used. On the other hand, when leakage current is occurring in the multiple electric circuits 7a-7c, the above characteristic does not hold, and therefore the self-diagnosis determination using the above characteristic cannot be used. For this reason, when the leakage current determination unit 31a determines that leakage current is occurring in the multiple electric circuits 7a-7c, the self-diagnosis determination unit 31c discards the result of the self-diagnosis determination.

[0070] If leakage current occurs in multiple electric circuits 7a to 7c, the following formula 2 holds, and therefore the above formula 1 does not hold.

[0071] Ia(t1)+Ib(t1)+Ic(t1)+Ie(t1)=0...Formula 2 Here, Ia(t1) to Ic(t1) are the first to third measurement values ​​at a given time t1, as above. Ie(t1) is the leakage current at the same time t1. In other words, if leakage occurs in multiple electric circuits 7a to 7c, the sum of the first to third measurement values ​​Ia(t1) to Ic(t1) at the same time t1 and the leakage current Ie(t1) will be zero.

[0072] The self-diagnosis determination unit 31c periodically performs a self-diagnosis determination, or the self-diagnosis determination unit 31c may perform the self-diagnosis determination before or after the overcurrent determination unit 31b performs an overcurrent determination.

[0073] The notification control unit 31e controls the notification unit 29 based on the determination results of the various determination units (overcurrent determination unit 31b, leakage determination unit 31a, and self-diagnosis determination unit 31c) to notify people around of the determination results of the various determination units. More specifically, when the overcurrent determination unit 31b determines that an overcurrent has occurred, the notification control unit 31e causes the corresponding light-emitting unit 291 to emit light and causes the sound output unit 292 to output a buzzer sound for a certain period of time. On the other hand, when the overcurrent determination unit 31b determines that an overcurrent has not occurred, the notification control unit 31e does not cause the corresponding light-emitting unit 291 to emit light and does not cause the sound output unit 292 to output a buzzer sound.

[0074] Furthermore, when the electric leakage determination unit 31a determines that an electric leakage has occurred, the notification control unit 31e causes the corresponding light emitting unit 291 to emit light and causes the sound output unit 292 to output a buzzer sound for a certain period of time. On the other hand, when the electric leakage determination unit 31a determines that an electric leakage has not occurred, the notification control unit 31e does not cause the corresponding light emitting unit 291 to emit light and does not cause the sound output unit 292 to output a buzzer sound.

[0075] Furthermore, when the self-diagnosis determination unit 31c determines that the plurality of current measuring units 27a to 27c are not normal, the notification control unit 31e causes the corresponding light emitting unit 291 to emit light and causes the sound output unit 292 to output a buzzer sound for a certain period of time. On the other hand, when the self-diagnosis determination unit 31c determines that the plurality of current measuring units 27a to 27c are normal, the notification control unit 31e does not cause the corresponding light emitting unit 291 to emit light and does not cause the sound output unit 292 to output a buzzer sound.

[0076] The drive control unit 31d controls the drive unit 26 to open and close the multiple contacts C1 based on the respective determination results of the overcurrent determination unit 31b and the leakage current determination unit 31a. More specifically, if the overcurrent determination unit 31b determines that an overcurrent has occurred or if the leakage current determination unit 31a determines that a ground fault has occurred, the drive control unit 31d controls the drive unit 26 to change the multiple contacts C1 from a closed state to an open state. This breaks the connection lines 24a to 24c, and the power supply from the AC power supply P1 to each load B1 is stopped. On the other hand, if the overcurrent determination unit 31b determines that an overcurrent has not occurred and the leakage current determination unit 31a determines that a ground fault has not occurred, the drive control unit 31d controls the drive unit 26 to maintain the multiple contacts C1 in a closed state. This brings the connection lines 24a to 24c into conduction, and the power supply from the AC power supply P1 to each load B1 is maintained.

[0077] The control board 32 is a circuit board on which the processing unit 31, the multiple current measurement units 27a to 27c, the zero-phase current transformer 28, the multiple light-emitting units 291, the sound output unit 292, etc. are mounted (FIG. 6). The control board 32 has multiple (for example, four) insertion holes 32a to 32d. For example, the processing unit 31, the multiple current measurement units 27a to 27c, the multiple light-emitting units 291, the sound output unit 292, etc. are arranged on the front main surface of the control board 32. For example, the zero-phase current transformer 28, etc. are arranged on the rear main surface of the control board 32.

[0078] The three insertion holes 32a to 32c constitute three current measurement units 27a to 27c. The three insertion holes 32a to 32c correspond one-to-one to the three connection lines 24a to 24c, and are holes into which the corresponding connection lines 24a to 24c are inserted. Coils 271 of the current measurement units 27a to 27c are arranged around the entire periphery of each of the insertion holes 32a to 32c in the control board 32. As a result, by inserting the connection lines 24a to 24c into the insertion holes 32a to 32c, the coils 271 of the current measurement units 27a to 27c are arranged around the connection lines 24a to 24c. The coils 271 are formed, for example, by printing on the control board 32.

[0079] The three connection wires 24a to 24c are collectively inserted into the insertion hole 32d. The zero-phase-sequence current transformer 28 is disposed around the insertion hole 32d on the rear main surface of the control board 32. The insertion hole 32d and the central hole of the zero-phase-sequence current transformer 28 are connected to each other. As a result, when the three connection wires 24a to 24c are collectively inserted into the insertion hole 32d, the three connection wires 24a to 24c are collectively inserted into the central hole of the zero-phase-sequence current transformer 28.

[0080] In this embodiment, the three connection wires 24a to 24c are arranged on the front main surface of the control board 32. One end of each of the three connection wires 24a to 24c is routed from the front to the rear of the control board 32 through the corresponding insertion holes 32a to 32c and connected to the corresponding primary terminals 21a to 21c via the corresponding contacts C1. The other end of each of the three connection wires 24a to 24c is routed collectively from the front to the rear of the control board 32 through the insertion hole 32d and connected to the corresponding secondary terminals 22a to 22c.

[0081] The power supply board 33 is a board on which the power supply circuit 30 and the like are mounted. The power supply board 33 is disposed behind the control board 32 and is housed in the body 34a (FIG. 4).

[0082] (3) Operation explanation The operation of the circuit breaker 20 of this embodiment will be described based on FIG.

[0083] When the current flowing through the connection lines 24a to 24c is equal to or less than a rated value (for example, a rated sensitivity current), the circuit breaker 20 closes the contacts C1 to allow the current to flow through the connection lines 24a to 24c, thereby supplying AC power from the AC power source P1 to each load B1.

[0084] In the circuit breaker 20, when an overcurrent flows through the multiple connection lines 24a to 24c, the current measuring units 27a to 27c measure the overcurrent, and the processing unit 31 (overcurrent determination unit 31b) determines that an overcurrent has occurred based on the measured value. Then, the processing unit 31 (drive control unit 31d) controls the drive unit 26 in accordance with the determination result to change the multiple contacts C1 from a closed state to an open state. This prevents the circuit breaker 20 from continuing to receive an overcurrent through the multiple connection lines 24a to 24c. At this time, the opening / closing mechanism 261 rotates the operating lever 25 from a closed position to an open position. Furthermore, the processing unit 31 (alert control unit 31e) controls the alarm unit 29 to alert people nearby that an overcurrent has occurred. After the cause of the overcurrent has been resolved, the operating lever 25 is returned from the open position to the closed position, causing the multiple contacts C1 to change from an open state to a closed state.

[0085] In the circuit breaker 20, when an imbalance occurs in the currents flowing through the plurality of connection lines 24a-24c due to a ground fault, the zero-phase-sequence current transformer 28 measures the imbalance, and the processing unit 31 (earth fault determination unit 31a) determines that a ground fault has occurred based on the measurement value. The processing unit 31 (drive control unit 31d) then controls the drive unit 26 to open the plurality of contacts C1 from the closed state in accordance with the determination result. This prevents the ground fault current from continuing to flow through the plurality of connection lines 24a-24c in the circuit breaker 20. At this time, the opening / closing mechanism 261 rotates the operating lever 25 from the closed position to the open position. The processing unit 31 (alert control unit 31e) also controls the alarm unit 29 to alert nearby people that a ground fault has occurred. After the cause of the ground fault has been resolved, the operating lever 25 is returned from the open position to the closed position, causing the plurality of contacts C1 to close.

[0086] Furthermore, in the circuit breaker 20, the processing unit 31 (self-diagnosis determination unit 31c) performs, for example, periodically, a self-diagnosis determination to determine whether the multiple current measurement units 27a-27c are normal based on the measurement values ​​of each of the multiple current measurement units 27a-27c. More specifically, the self-diagnosis determination unit 31c performs, for example, periodically, a self-diagnosis determination to determine whether the multiple current measurement units 27a-27c are normal, depending on whether the sum of the measurement values ​​of the multiple current measurement units 27a-27c at the same time is zero. If the sum of the measurement values ​​of the multiple current measurement units 27a-27c at the same time is zero, the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a-27c are normal. On the other hand, if the sum of the measurement values ​​of the multiple current measurement units 27a-27c at the same time is not zero, the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a-27c are abnormal.

[0087] Furthermore, when the self-diagnosis determination unit 31c issues a result of the self-diagnosis determination, if the leakage current determination unit 31a determines that no leakage current has occurred, the self-diagnosis determination unit 31c validates the result of the self-diagnosis determination. Furthermore, when the self-diagnosis determination unit 31c issues a result of the self-diagnosis determination, if the leakage current determination unit 31a determines that a leakage current has occurred, the self-diagnosis determination unit 31c discards the result of the self-diagnosis determination.

[0088] Then, when the self-diagnosis determination unit 31c determines that the plurality of current measurement units 27a to 27c are not normal and the determination result is valid, the processing unit 31 (notification control unit 31e) controls the notifying unit 29 to notify people around that the plurality of current measurement units 27a to 27c are not normal. On the other hand, when the self-diagnosis determination unit 31c determines that the plurality of current measurement units 27a to 27c are normal and the determination result is valid, the processing unit 31 (notification control unit 31e) does not notify the determination result. In other words, only when the plurality of current measurement units 27a to 27c are not normal, the determination result of the self-diagnosis determination is notified from the notifying unit 29. Note that the determination result of the self-diagnosis determination may be notified from the notifying unit 29 not only when the plurality of current measurement units 27a to 27c are not normal, but also when the plurality of current measurement units 27a to 27c are normal.

[0089] In this way, when the plurality of current measuring units 27a to 27c are not normal, this fact is quickly notified to people around, thereby ensuring the reliability of the plurality of current measuring units 27a to 27c. As a result, the reliability of the determination result of overcurrent determining unit 31b, which is determined based on the measurement values ​​of the plurality of current measuring units 27a to 27c, can also be ensured.

[0090] (4) Main Effects The current measuring device 40 according to this embodiment includes a plurality of current measuring units 27a-27c and a self-diagnosis determination unit 31c. The plurality of current measuring units 27a-27c measure the current flowing through each of a plurality of electrical paths 7a-7c that constitute a set of electrical paths through which an AC current flows. The self-diagnosis determination unit 31c performs a self-diagnosis determination as to whether the plurality of current measuring units 27a-27c are normal. With this configuration, the self-diagnosis determination unit 31c can ensure the reliability of the plurality of current measuring units 27a-27c.

[0091] The circuit breaker 20 according to this embodiment is a circuit breaker equipped with a current measuring device 40. The circuit breaker 20 includes a plurality of contacts C1, the current measuring device 40, an overcurrent determination unit 31b, and a drive control unit 31d. The plurality of contacts C1 open and close a plurality of electric circuits 7a-7c that constitute a set of electric circuits for supplying AC power from an AC power source P1 to one or more loads B1. The current measuring device 40 includes a plurality of current measuring units 27a-27c that measure currents flowing through the plurality of electric circuits 7a-7c. The overcurrent determination unit 31b determines whether an overcurrent has occurred in the plurality of electric circuits 7a-7c based on the measurement values ​​of each of the plurality of current measuring units 27a-27c. The drive control unit 31d opens and closes the plurality of contacts C1 via the drive unit 26 based on the determination result of the overcurrent determination unit 31b. This configuration provides the circuit breaker 20 with the operational effect of the above-described current measuring device 40.

[0092] Moreover, the distribution board 1 according to this embodiment includes a circuit breaker 20 and a cabinet 10 that holds the circuit breaker 20. With this configuration, it is possible to provide a distribution board 1 that has the same operational effects as the circuit breaker 20.

[0093] (5) Variations The above-described embodiment is merely one of various embodiments of the present disclosure. The above-described embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the above-described embodiment are listed below. The modifications described below and the above-described embodiment can be applied in appropriate combination.

[0094] (5.1) Variation 1 In the above embodiment, a single-phase three-wire system is exemplified as the AC power distribution system, but a three-phase four-wire system, a three-phase three-wire system, or a single-phase two-wire system may also be used. In these cases, the characteristic that the sum of the current values ​​(measured values) of the currents flowing through the electrical circuits corresponding to each line at the same time is zero holds. Therefore, as in the above embodiment, a self-diagnosis determination can be made as to whether the multiple current measurement units, which measure the currents flowing through the electrical circuits, are normal or not, depending on whether the sum of the measured values ​​of each current measurement unit at the same time is zero.

[0095] (5.2) Variation 2 In the above embodiment, the self-diagnosis determination unit 31c performs self-diagnosis determination using measurement values ​​(i.e., instantaneous values) at the same time from the multiple current measurement units 27a to 27c. In contrast, in Modification 2, the self-diagnosis determination unit 31c performs self-diagnosis determination using effective values ​​of measurement values ​​at the same time period from the multiple current measurement units 27a to 27c. The effective values ​​are the square root of the time average value of the squares of the measurement values ​​(e.g., the time average value for one cycle).

[0096] More specifically, the self-diagnosis determination unit 31c of the second modification acquires a measurement signal from each of the current measurement units 27a-27c. The self-diagnosis determination unit 31c then obtains a measurement value (digital value) from each of the measurement signals (analog values) of the current measurement units 27a-27c, and calculates the effective values ​​of the measurement values ​​of the current measurement units 27a-27c for the same time period Δt1 based on the obtained measurement values. Here, the effective value of the measurement value of the current flowing through the L1-phase electric circuit 7a for the predetermined time period Δt1 is defined as a first effective value Ja(Δt1). The effective value of the measurement value of the current flowing through the L2-phase electric circuit 7b for the predetermined time period Δt1 is defined as a second effective value Jb(Δt1). The effective value of the measurement value of the current flowing through the N-phase electric circuit 7c for the predetermined time period Δt1 is defined as a third effective value Jc(Δt1). In addition, in the second modification, as in the above embodiment, it is assumed that the AC power distribution system is a single-phase three-wire system.

[0097] At this time, the self-diagnosis judgment unit 31c judges whether the multiple current measuring units 27a to 27c are normal or not, depending on whether the absolute value of the difference between the first effective value Ja(Δt1) and the second effective value Jb(Δt1) is equal to the third effective value Jc(Δt1) (i.e., whether the following equation 3 is satisfied).

[0098] |Ja(Δt1)-Jb(Δt1)|=Jc(Δt1)…Equation 3 Note that Equation 3 is substantially the same as Equation 1 of the embodiment in which the measured values ​​Ia(t1) to Ic(t1) are replaced with the effective values ​​Ja(Δt1) to Jc(Δt1).

[0099] More specifically, if the absolute value of the difference between the first effective value Ja(Δt1) and the second effective value Jb(Δt1) is equal to the third effective value Jc(Δt1) (i.e., if formula 3 holds), the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a-27c are normal. On the other hand, if the absolute value of the difference between the first effective value Ja(Δt1) and the second effective value Jb(Δt1) is not equal to the third effective value Jc(Δt1) (i.e., if formula 3 does not hold), the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a-27c are abnormal.

[0100] Note that the above statement that "the absolute value of the difference between the first effective value Ja(Δt1) and the second effective value Jb(Δt1) is equal to the third effective value Jc(Δt1)" is not limited to being strictly equal, but may include an error that allows them to be considered substantially equal.

[0101] For example, if the first effective value Ja(Δt1)=60 Arms, the second effective value Jb(Δt1)=100 Arms, and the third effective value Jc(Δt1)=40 Arms, then |Ja(Δt1)-Jb(Δt1)|=40 Arms=Jc(Δt1). Therefore, in this case, the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a to 27c are normal.

[0102] According to the second modification, the self-diagnosis determination uses the effective values ​​measured by the multiple current measuring units 27a to 27c in the same time period. In this case, even if the time periods of the first to third effective values ​​are slightly different from each other, the self-diagnosis determination can be performed accurately. Therefore, compared to the first embodiment (i.e., when the self-diagnosis determination is performed using measured values ​​at the same time), the calculation load on the self-diagnosis determination unit 31c for adjusting the time periods of the first to third effective values ​​can be reduced.

[0103] (5.3) Variation 3 In the above embodiment, the self-diagnosis determination unit 31c performs self-diagnosis determination using measurement values ​​(i.e., instantaneous values) at the same time from the multiple current measurement units 27a to 27c. In contrast, in Modification 3, the self-diagnosis determination unit 31c performs self-diagnosis determination using an integral value of the measurement values ​​at the multiple current measurement units 27a to 27c during the same time period. Note that the integral value is a value (integral value) obtained by integrating the measurement values ​​over a certain period of time (for example, one minute).

[0104] More specifically, the self-diagnosis determination unit 31c of the third modification acquires a measurement signal from each of the current measurement units 27a to 27c. The self-diagnosis determination unit 31c then obtains a measurement value (digital value) from each of the measurement signals (analog values) of the current measurement units 27a to 27c, and calculates an integral of the measurement values ​​of the current measurement units 27a to 27c during the same time period Δt1 based on the obtained measurement value. Here, the integral of the measurement value of the current flowing through the L1-phase electric circuit 7a during the predetermined time period Δt1 is defined as a first integral value Sa(Δt1). The integral of the measurement value of the current flowing through the L2-phase electric circuit 7b during the predetermined time period Δt1 is defined as a second integral value Sb(Δt1). The integral of the measurement value of the current flowing through the N-phase electric circuit 7c during the predetermined time period Δt1 is defined as a third integral value Sc(Δt1). In addition, in the third modification, as in the above embodiment, it is assumed that the AC power distribution system is a single-phase three-wire system.

[0105] At this time, the self-diagnosis judgment unit 31c judges whether the multiple current measurement units 27a to 27c are normal or not, depending on whether the absolute value of the difference between the first integral value Sa(Δt1) and the second integral value Sb(Δt1) is equal to the third integral value Sc(Δt1) (i.e., whether the following equation 4 is satisfied).

[0106] |Sa(Δt1)-Sb(Δt1)|=Sc(Δt1)…Equation 4 Note that Equation 4 is substantially the same as Equation 1 of the embodiment in which the measurement values ​​Ia(t1) to Ic(t1) are replaced with the integral values ​​Sa(Δt1) to Sc(Δt1).

[0107] More specifically, if the absolute value of the difference between the first integral value Sa(Δt1) and the second integral value Sb(Δt1) is equal to the third integral value Sc(Δt1) (i.e., if formula 4 is satisfied), the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a to 27c are normal. On the other hand, if the absolute value of the difference between the first integral value Sa(Δt1) and the second integral value Sb(Δt1) is not equal to the third integral value Sc(Δt1) (i.e., if formula 4 is not satisfied), the self-diagnosis determination unit 31c determines that the multiple current measurement units 27a to 27c are abnormal.

[0108] Note that the above statement that "the absolute value of the difference between the first integral value Sa(Δt1) and the second integral value Sb(Δt1) is equal to the third integral value Sc(Δt1)" is not limited to being strictly equal, but may include an error that allows them to be considered substantially equal.

[0109] According to the third modification, the self-diagnosis determination is performed using the integrated value of the measurement value, so that the self-diagnosis determination can be performed accurately even if the measurement value is small (i.e., even if the current flowing through the multiple electrical circuits 7a to 7c is very small).

[0110] (6) Aspects The following aspects are disclosed from the above-described embodiments and modifications.

[0111] The current measuring device (40) of the first aspect includes a plurality of current measuring units (27a-27c) and a self-diagnosis determination unit (31c). The plurality of current measuring units (27a-27c) measure the current flowing through each of a plurality of electric paths (7a-7c) constituting a set of electric paths through which an AC current flows. The self-diagnosis determination unit (31c) performs a self-diagnosis determination of whether the plurality of current measuring units (27a-27c) are normal or not, based on the measurement values ​​of each of the plurality of current measuring units (27a-27c).

[0112] According to this configuration, the self-diagnosis determination section (31c) can ensure the reliability of the plurality of current measurement sections (27a-27c).

[0113] In the current measuring device (40) of the second aspect, in the first aspect, the self-diagnosis determination unit (31c) performs self-diagnosis determination depending on whether the sum of the measurement values ​​(Ia(t1) to Ic(t1)) measured at the same time (t1) by the multiple current measuring units (27a to 27c) is zero.

[0114] According to this configuration, it is possible to determine (self-diagnosis determination) whether the plurality of current measurement units (27a to 27c) are normal or not using a simple determination principle.

[0115] In the current measuring device (40) of the third aspect, in the second aspect, the multiple electric paths (7a-7c) are configured with a first voltage line (7a), a second voltage line (7b) that is in phase opposite to the first voltage line (7a), and a grounded neutral line (7c). The measured value of the current flowing through the first voltage line (7a) is defined as a first measured value (Ia(t1)). The measured value of the current flowing through the second voltage line (7b) is defined as a second measured value (Ib(t1)). The measured value of the current flowing through the neutral line (7c) is defined as a third measured value (Ic(t1)). The self-diagnosis determination unit (31c) performs self-diagnosis determination depending on whether the sum of the first measured value (Ia(t1)), the second measured value (Ib(t1)), and the third measured value (Ic(t1)) is zero.

[0116] This configuration is suitable when a set of electric paths (that is, a plurality of electric paths (7a to 7c)) through which AC current flows are single-phase three-wire electric paths.

[0117] In the current measuring device (40) of the fourth aspect, in the first aspect, the multiple electric circuits (7a-c) are configured with a first voltage line (7a), a second voltage line (7b) that is in opposite phase to the first voltage line (7a), and a grounded neutral line (7c). The effective value of the measured value of the current flowing through the first voltage line (7a) during a predetermined time period (Δt1) is defined as a first effective value (Ja(Δt1)). The effective value of the measured value of the current flowing through the second voltage line (7b) during the predetermined time period (Δt1) is defined as a second effective value (Jb(Δt1)). The effective value of the measured value of the current flowing through the neutral line (7c) during the predetermined time period (Δt1) is defined as a third effective value (Jc(Δt1)). The self-diagnosis determination section (31c) makes a self-diagnosis determination depending on whether the absolute value of the difference between the first effective value (Ja(Δt1)) and the second effective value (Jb(Δt1)) is equal to the third effective value (Jc(Δt1)).

[0118] According to this configuration, the self-diagnosis determination uses the effective values ​​(Ja(Δt1) to Jc(Δt1)) of the measured values ​​in the same time period (Δt1) of the multiple current measuring units (27a to 27c). In this case, even if the time periods of the first to third effective values ​​(Ja(Δt1) to Jc(Δt1)) are slightly different from each other, the self-diagnosis determination can be performed accurately. This reduces the computational load on the self-diagnosis determination unit (31c) for aligning the time periods (Δt1) of the first to third effective values ​​(Ja(Δt1) to Jc(Δt1)).

[0119] In the current measuring device (40) of the fifth aspect, in the first aspect, the multiple electric circuits (7a-7c) are configured with a first voltage line (7a), a second voltage line (7b) that is in opposite phase to the first voltage line (7a), and a grounded neutral line (7c). The integral of the measured value of the current flowing through the first voltage line (7a) during a predetermined time period (Δt1) is defined as a first integral value (Sa(Δt1)). The integral of the measured value of the current flowing through the second voltage line (7b) during the predetermined time period (Δt1) is defined as a second integral value (Sb(Δt1)). The integral of the measured value of the current flowing through the neutral line (7c) during the predetermined time period (Δt1) is defined as a third integral value (Sc(Δt1)). The self-diagnosis determination section (31c) makes a self-diagnosis determination depending on whether the absolute value of the difference between the first integral value (Sa(Δt1)) and the second integral value (Sb(Δt1)) is equal to the third integral value (Sc(Δt1)).

[0120] According to this configuration, the self-diagnosis judgment is performed using the integral value of the measurement value (Sa(Δt1) to Sc(Δt1)), so that even if the measurement value is small (i.e., even if the current flowing through the multiple electrical circuits (7a to 7c) is very small), the self-diagnosis judgment can be performed accurately.

[0121] The current measuring device (40) of a sixth aspect is the current measuring device (40) of any one of the first to fifth aspects, further including a zero-phase-sequence current transformer (28) and a leakage current determination unit (31a). The zero-phase-sequence current transformer (28) measures an imbalance in current flowing through each of the plurality of electric circuits (7a to 7c). The leakage current determination unit (31a) determines whether or not a leakage current has occurred based on a measurement value of the zero-phase-sequence current transformer (28). The self-diagnosis determination unit (31c) discards the result of the self-diagnosis determination when the leakage current determination unit (31a) determines that a leakage current has occurred.

[0122] This configuration can prevent the self-diagnosis determining section (31c) from giving an erroneous determination result when a ground fault occurs.

[0123] In the current measuring device (40) of the seventh aspect, in any one of the first to sixth aspects, the plurality of current measuring units (27a to 27c) have a substrate (32) and a coil (271) printed on the substrate (32).

[0124] According to this configuration, the current measuring units (27a to 27c) can be configured simply.

[0125] A circuit breaker (20) according to an eighth aspect includes the current measurement device (40) according to any one of the first to seventh aspects. The circuit breaker (20) includes a plurality of contacts (C1), the current measurement device (40), an overcurrent determination unit (31b), and a drive control unit (31d). The plurality of contacts (C1) open and close a plurality of electric circuits (7a-7c) that constitute a set of electric circuits for supplying AC power from an AC power source (P1) to one or more loads (B1). The current measurement device (40) includes a plurality of current measurement units (27a-27c) that measure currents flowing through the plurality of electric circuits (7a-7c). The overcurrent determination unit (31b) determines whether an overcurrent has occurred in the plurality of electric circuits (7a-7c) based on the measurement values ​​of the respective current measurement units (27a-27c). The drive control section (31d) controls the drive section (26) based on the determination result of the overcurrent determination section (31b) to open the plurality of contacts (C1).

[0126] According to this configuration, it is possible to provide a circuit breaker (20) that has the function and effect of the current measuring device (40).

[0127] A distribution board (1) of a ninth aspect includes a circuit breaker (20) according to any one of the first to eighth aspects, and a cabinet (10) that holds the circuit breaker (20).

[0128] This configuration makes it possible to provide a distribution board (1) that has the function and effect of a circuit breaker (20). [Explanation of symbols]

[0129] 1 Distribution board 10 Cabinet 7a L1 phase circuit (electric circuit, 1st voltage line) 7b L2 phase circuit (electric circuit, second voltage line) 7c N phase circuit (electric circuit, neutral line) 26 Drive unit 27a~27c Current measurement section 28 Zero phase current transformer 31a Earth leakage determination section 31b Overcurrent judgment section 31d Drive control unit 31c Self-diagnosis judgment section 32 Control board 40 Current measuring device B1 load t1: fixed time (time) Δt1 specified time period Ia(t1) First measurement value Ib(t1) Second measurement value Ic(t1) 3rd measurement value Ja(Δt1) First effective value Jb(Δt1) Second effective value Jc(Δt1) 3rd effective value Sa(Δt1) First integral value Sb(Δt1) Second integral value Sc(Δt1) Third integral value

Claims

1. A set of electric circuits through which AC current flows to supply power to a load connected to a two-wire electric circuit, the set of electric circuits being branched from the two-wire electric circuit, and multiple current measuring units for measuring the current flowing through each of the multiple electric circuits constituting the set of electric circuits; a self-diagnosis determination unit that performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units, the self-diagnosis determination unit performs the self-diagnosis determination depending on whether a sum of measurement values ​​measured by the plurality of current measurement units at the same time is zero. Current measuring device.

2. a plurality of current measuring units that measure currents flowing through each of a plurality of electric paths that constitute a set of electric paths through which an AC current flows; a self-diagnosis determination unit that performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units, the self-diagnosis determination unit performs the self-diagnosis determination depending on whether a sum of measurement values ​​measured by the plurality of current measurement units at the same time is zero or not; the plurality of electric paths are composed of a first voltage line, a second voltage line that is in opposite phase to the first voltage line, and a grounded neutral line; The measured value of the current flowing through the first voltage line is defined as a first measured value; The measured value of the current flowing through the second voltage line is defined as a second measured value; The measurement of the current flowing through the neutral conductor is defined as a third measurement; the self-diagnosis determination unit performs the self-diagnosis determination depending on whether a sum of the first measurement value, the second measurement value, and the third measurement value is zero. Current measuring device.

3. a plurality of current measuring units that measure currents flowing through each of a plurality of electric paths that constitute a set of electric paths through which an AC current flows; a self-diagnosis determination unit that performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units, the plurality of electric paths are composed of a first voltage line, a second voltage line that is in opposite phase to the first voltage line, and a grounded neutral line; an effective value of the measured value of the current flowing through the first voltage line in a predetermined time period is defined as a first effective value; The effective value of the measured value of the current flowing through the second voltage line during the predetermined time period is defined as a second effective value; The effective value of the measurement value of the current flowing through the neutral conductor during the predetermined time period is defined as a third effective value; the self-diagnosis determination unit performs the self-diagnosis determination depending on whether an absolute value of a difference between the first effective value and the second effective value is equal to the third effective value. Current measuring device.

4. a plurality of current measuring units that measure currents flowing through each of a plurality of electric paths that constitute a set of electric paths through which an AC current flows; a self-diagnosis determination unit that performs a self-diagnosis determination as to whether the plurality of current measurement units are normal based on the measurement values ​​of each of the plurality of current measurement units, the plurality of electric paths are composed of a first voltage line, a second voltage line that is in opposite phase to the first voltage line, and a grounded neutral line; an integral value of the measured value of the current flowing through the first voltage line over a predetermined time period is defined as a first integral value; an integral value of the measured value of the current flowing through the second voltage line during the predetermined time period is defined as a second integral value; An integral value of the measurement value of the current flowing through the neutral conductor during the predetermined time period is defined as a third integral value; the self-diagnosis determination unit makes the self-diagnosis determination depending on whether an absolute value of a difference between the first integral value and the second integral value is equal to the third integral value. Current measuring device.

5. a plurality of current measuring units that measure currents flowing through each of a plurality of electric paths that constitute a set of electric paths through which an AC current flows; a self-diagnosis determination unit that performs a self-diagnosis determination as to whether the plurality of current measurement units are normal or not based on the measurement values ​​of each of the plurality of current measurement units; a zero-phase-sequence current transformer that measures an imbalance in current flowing through each of the plurality of electric paths; a leakage current determination unit that determines whether or not a leakage current has occurred based on the measurement value of the zero-phase current transformer, When the electric leakage determination unit determines that an electric leakage has occurred, the self-diagnosis determination unit discards the determination result of the self-diagnosis determination. Current measuring device.

6. a zero-phase-sequence current transformer that measures an imbalance in current flowing through each of the plurality of electric paths; and a leakage current determination unit that determines whether or not a leakage current has occurred based on the measurement value of the zero-phase current transformer, When the electric leakage determination unit determines that an electric leakage has occurred, the self-diagnosis determination unit discards the determination result of the self-diagnosis determination. The current measuring device according to any one of claims 1 to 4.

7. The plurality of current measurement units each include a substrate and a coil printed on the substrate. The current measuring device according to any one of claims 1 to 5.

8. A circuit breaker equipped with the current measuring device according to any one of claims 1 to 5, a plurality of contacts for opening and closing a plurality of electric paths that constitute a set of electric paths for supplying AC power from an AC power source to one or more loads; the current measuring device including the plurality of current measuring units that measure currents flowing through the plurality of electrical paths; an overcurrent determination unit that determines whether an overcurrent has occurred in the plurality of electrical paths based on the measurement values ​​of each of the plurality of current measurement units; a drive control unit that controls a drive unit to open the plurality of contacts based on a determination result of the overcurrent determination unit, Circuit breaker.

9. A circuit breaker according to claim 8; a cabinet for holding the circuit breaker; Equipped with Distribution board.

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