Electronic trip unit of molded case circuit breaker

Abstract

The present invention relates to an electronic trip unit of a molded case circuit breaker and, more specifically, to an electronic trip unit of a molded case circuit breaker in which the electronic trip unit has an inter-phase interference prevention function. According to an electronic trip unit of a molded case circuit breaker according to one embodiment of the present invention, a magnetic field absorber surrounding a Rogowski coil is provided in a current detection unit and prevents a magnetic field from spreading to an adjacent phase.

Description

Electronic trip unit of circuit breaker for wiring

[0001] The present invention relates to an electronic trip unit of a circuit breaker for wiring, and more particularly, to an electronic trip unit of a circuit breaker for wiring having a function of preventing interphase current interference.

[0002] In general, a molded case circuit breaker (MCCB) is an electrical device that automatically cuts off the circuit in the event of an electrical overload or short circuit to protect the circuit and load. It is largely composed of a terminal section connected to the power source or load side, a contact section consisting of a fixed contact and a movable contact, a switching mechanism section that provides driving force so that the movable contact can mechanically contact the fixed contact, a trip section that detects overcurrent or short-circuit current occurring in the circuit and induces a trip operation of the switching mechanism, and an arc extinguishing section to extinguish an arc that occurs when an abnormal current is interrupted.

[0003] Fig. 1 illustrates a cross-sectional view of a circuit breaker according to the prior art. The circuit breaker according to the prior art includes a fixed contact (2a, 2c) and a movable contact (2b) that constitute a contact portion provided to connect or cut off a circuit transmitted from a power source side to a load side inside an outer case (1) formed of an insulating material, a switching mechanism (3) that provides power to rotate the movable contact (2b), an arc extinguishing portion (4) that is provided to extinguish an arc generated when a fault current is cut off, a detection mechanism portion that detects an abnormal current, etc. Here, the detection mechanism portion may be composed of an electronic trip portion (5).

[0004] Fig. 2 shows a perspective view of an electronic trip unit (5) according to the prior art. It is composed of a trip unit stator (6) that supplies current to a current transformer (CT) (7) from a load-side fixed contact (2c), a current transformer (7) that converts the applied current into a small current, a current transformer receiving unit (8), a control unit (PCB) (9) that drives a circuit with the current converted by the current transformer (7) and operates a trip coil (not shown) when an abnormal current occurs, etc.

[0005] When an abnormal current occurs in the circuit (10), the control signal from the control unit (9) is received, and the trip coil operates the opening / closing mechanism (3) to cut off the circuit. As the circuit breaker performs the breaking operation, the arc is extinguished in the arc extinguishing unit (4).

[0006] Figure 3 shows a block diagram of the fault current blocking mechanism.

[0007] The part mainly related to the current detection function in the electronic trip unit (5) is composed of a current detection unit (Signal CT) (7a), a power generation unit (Power CT) (7b), and a control unit (9).

[0008] The control unit (9) receives power from the power generation unit (7b) and operates. The control unit (9) receives the magnitude and phase of the current through the current detection unit (7a), determines whether there is an accident, operates the trip coil, operates the switching mechanism unit (3), and blocks the circuit. Accordingly, it performs the function of isolating and blocking the faulty section from the healthy section in the circuit.

[0009] Here, the control unit (9) measures the electric quantity using the current detection unit (7a) and voltage generation unit (7c) of the electronic trip unit (5), and then uses this as a basis for judging fault current, etc. This data requires high measurement precision so that it can replace the metering or measuring devices of the power system.

[0010] However, errors may occur in current measurement due to phase-to-phase current interference in the current transformer (7).

[0011] Let’s take a closer look at the transformer (7).

[0012] The current detection unit (7a) and the power generation unit (7b) have a structure in which the bus bar (one of the R phase, S phase, and T phase) of the circuit (10) passes through.

[0013] The current detection unit (7a) uses a Rogowski coil, which has the advantage of being small in size and having no saturation characteristics, as shown in Fig. 4.

[0014] The power generation unit (7b), on the other hand, uses a CT using an iron core with saturation characteristics as shown in Fig. 5. Normally, the current detection unit (7a) and the power generation unit (7b) are configured in the same position through which the bus bar can pass, as shown in Figs. 6a and 6b, in order to effectively use the small size of the wiring circuit breaker, and are arranged as shown in Fig. 7 according to the number of poles (three in the case of three phases) of the wiring circuit breaker.

[0015] In the small size of the circuit breaker for wiring, the current flowing in each phase distorts the magnitude and phase of the current in other phases. This phenomenon is called interphase current interference, and it had to be resolved to increase measurement accuracy.

[0016] In order to reduce this interphase current interference phenomenon, conventional technologies have managed various matters such as uniform winding management of Rogowski coils, management of the starting and ending points of Rogowski coil windings, and separation of lead wires. However, this has the problem that the manufacturing period of the current transformer is long, the equipment becomes complicated, and the effect of reducing the interphase current interference phenomenon is not significant.

[0017] As a prior art document related to the present invention, reference may be made to Republic of Korea Utility Model Registration No. 20-0487464, ‘Circuit Breaker for Wiring.’

[0018] The present invention has been devised to solve the above-mentioned problem, and its purpose is to provide an electronic trip unit of a wiring circuit breaker that reduces interphase interference caused by magnetic fields of adjacent phases and minimizes errors in measured current.

[0019] According to one embodiment of the present invention, an electronic trip unit of a circuit breaker for a wiring type is characterized in that a circuit is connected from a power source side to a load side, and an alternating current having multiple phases flows through the circuit, wherein a current transformer is provided for each of the multiple phases to measure the alternating current, and the current transformer includes a current detection unit that measures the current of one of the phases in which the current transformer is installed among the multiple phases, and the current detection unit is provided with a magnetic field absorbing material that absorbs a magnetic field generated in one of the phases and prevents it from spreading to other phases.

[0020] Here, the transformer further includes a power generation unit that generates voltage by induced electromotive force generated in one of the plurality of phases on which the transformer is installed.

[0021] In addition, it further includes a control unit that operates by receiving power provided from the power generation unit and blocks the circuit when the current signal transmitted from the current detection unit is determined to be a fault current.

[0022] In addition, a transformer receiving portion for receiving the transformer is provided in the trip portion case forming the outer case of the electronic trip portion.

[0023] In addition, the transformer receiving portion is provided with a connecting conductor insertion portion in which a connecting conductor connected to the circuit is installed.

[0024] In addition, the current detection unit includes a Rogowski coil having a through hole; and a first magnetic field absorbing material among the magnetic field absorbing materials that surrounds the Rogowski coil.

[0025] In addition, the current detection unit further includes a first magnetic field absorbing material fixing member that is fixedly installed in the transformer receiving unit, accommodates the Rogowski coil inside, and has the first magnetic field absorbing material installed outside.

[0026] In addition, a transformer mounting portion is formed protrudingly in the transformer receiving portion, and a center hole is formed in the first magnetic field absorbing material fixing member to be fitted into the transformer mounting portion.

[0027] In addition, the first magnetic field absorbing material fixing member has a front portion and a side portion, and the side portion has a curved portion and a flat portion.

[0028] Additionally, the inner diameter of the central hole is formed smaller than the inner diameter of the Rogowski coil.

[0029] In addition, the width of the side portion of the first magnetic field absorbing material fixing member is formed to be larger than the width of the side portion of the Rogowski coil.

[0030] In addition, the Rogowski coil, the first magnetic field absorber fixing member, and the first magnetic field absorber are joined to each other by a molding method.

[0031] Additionally, the power generation unit includes an iron core and a coil, and the magnetic field absorbing material includes a second magnetic field absorbing material surrounding the iron core and the coil.

[0032] Additionally, the magnetic field absorber is formed of a material having a high permeability.

[0033] And, the magnetic field absorber is formed of permalloy or nano-crystalline.

[0034] According to an electronic trip unit of a circuit breaker for wiring according to one embodiment of the present invention, a magnetic field absorbing material is provided to wrap a Rogowski coil in a current detection unit, thereby preventing a magnetic field from spreading to an adjacent phase.

[0035] Additionally, a magnetic field absorbing material is provided to surround the iron core and coil in the power generating section to prevent the magnetic field from spreading to adjacent phases.

[0036] Accordingly, current measurement errors due to phase-to-phase interference when abnormal current occurs in the circuit are minimized.

[0037] Additionally, the interphase distance can be reduced because the interphase interference is prevented, thereby reducing the overall size.

[0038] Figure 1 is a cross-sectional view of a wiring circuit breaker according to the prior art.

[0039] Fig. 2 is a perspective view of an electronic trip unit applied to a wiring circuit breaker according to the prior art.

[0040] Figure 3 is a block diagram of an electronic trip unit according to the prior art.

[0041] Fig. 4 shows a current detection unit of an electronic trip unit according to the prior art.

[0042] Figures 5a and 5b show a power generation unit of an electronic trip unit according to the prior art.

[0043] Figures 6a and 6b show a transformer of an electronic trip unit according to the prior art.

[0044] Figure 7 shows a state in which a transformer is assembled in an electronic trip unit according to the prior art and that phase interference occurs.

[0045] Figure 8 is a cross-sectional view of a wiring circuit breaker according to one embodiment of the present invention.

[0046] FIG. 9 and FIG. 10 are perspective views of an electronic trip unit applied to a wiring circuit breaker according to one embodiment of the present invention.

[0047] Figure 11 is an exploded perspective view of Figure 10.

[0048] Figure 12 is a rear view of the electronic trip unit. The electronic trip unit cover is removed.

[0049] Fig. 13 is a perspective view of a transformer applied to the electronic trip unit of the present invention.

[0050] Fig. 14 is an exploded perspective view of the current detection unit in Fig. 13.

[0051] Fig. 15 is an exploded perspective view of the power generation unit in Fig. 13.

[0052] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, these drawings are intended to provide a detailed description sufficient to enable those skilled in the art to easily practice the invention, and are not intended to limit the technical spirit or scope of the present invention.

[0053] The terms “absence” or “part” used to refer to components in the present invention are not used for any limiting purpose and may be omitted.

[0054] Hereinafter, an electronic trip unit of a circuit breaker for wiring according to each embodiment of the present invention will be described in detail with reference to the drawings. Fig. 8 is a longitudinal cross-sectional view of a circuit breaker for wiring according to one embodiment of the present invention, Figs. 9 and 10 are perspective views of an electronic trip unit applied to a circuit breaker for wiring according to one embodiment of the present invention, and Fig. 11 is an exploded perspective view of Fig. 10.

[0055] According to one embodiment of the present invention, an electronic trip unit of a circuit breaker for a wiring system is applied to a circuit breaker for a wiring system having a plurality of phases (R, S, T) through which an alternating current flows from a power source (P) side to a load (L) side, and a current transformer (300) is provided for each of the plurality of phases (R, S, T) to measure the alternating current, and the current transformer (300) includes a current detection unit (310) for sensing the current of one of the plurality of phases (R, S, T) in which the current transformer (300) is installed; and a power generation unit (350) for generating a voltage by an induced electromotive force generated in one of the phases, and the current detection unit (310) or the power generation unit (350) is characterized in that a magnetic field absorbing material (330, 370) is provided for absorbing a magnetic field generated in one of the phases and preventing it from spreading to other phases.

[0056] Figure 8 shows a cross-sectional view of a wiring circuit breaker (100) according to one embodiment of the present invention.

[0057] The basic configuration of the wiring circuit breaker according to the present invention follows that of a general wiring circuit breaker.

[0058] A circuit breaker for wiring is provided with a case (101) formed of an insulating material. The case (101) accommodates and supports components inside.

[0059] A contact portion is provided inside the outer case (101) to connect or disconnect a circuit transmitted from the power side to the load side. The contact portion includes a fixed contact portion (111, 112) and a movable contact portion (113) that contacts or separates from the fixed contact portion.

[0060] The opening / closing mechanism (120) provided on the upper part of the contact portion provides power to rotate the movable contact (113).

[0061] The arc protection unit (130) is provided to extinguish the arc that occurs when the accident current is interrupted.

[0062] A detection and trip unit for detecting abnormal current is provided. Here, the detection and trip unit may be configured as an electronic trip unit (200).

[0063] Here, the trip unit (200) includes a trip unit stator (198) connected to a fixed contact (112), a connecting conductor (220), a current transformer (300) that converts the current flowing in the connecting conductor (220), and a control unit (240) that operates the opening / closing mechanism (120) by operating the current applied from the current transformer (300).

[0064] Figures 9 and 10 illustrate perspective views of the electronic trip unit. Figure 9 illustrates the front of the electronic trip unit, and Figure 10 illustrates the rear of the electronic trip unit. Meanwhile, Figure 11 illustrates an exploded perspective view of the electronic trip unit.

[0065] The trip unit case (201) can be formed as a molded injection molded product. That is, the trip unit case (201) can be configured as a mold housing.

[0066] A control unit housing (202) is provided on the upper part of the trip unit case (201), and a transformer housing (203) is provided on the lower part of the trip unit case (201). Here, the control unit housing (202) and the transformer housing (203) may be formed integrally. Meanwhile, a transformer housing cover (210) is provided on the rear part of the trip unit case (201).

[0067] A control unit (240) is installed in the control unit housing (202). The control unit (240) may be composed of a circuit board (PCB). The control unit (240) receives a current signal from a current transformer (300).

[0068] A current transformer housing (203) is formed with a current transformer receiving portion (205) into which a current transformer (300) is inserted. The current transformer receiving portion (205) occupies most of the space of the current transformer housing (203). A current transformer housing cover (210) covers the current transformer receiving portion (205). A current transformer (300) is inserted and installed in the current transformer receiving portion (205). A current transformer receiving portion (205) is provided for each phase in the current transformer housing (203). For example, in the case of a three-phase circuit of R, S, and T, three current transformer receiving portions (205) for the R phase, S phase, and T phase are provided in the current transformer housing (203).

[0069] The transformer (300) is provided to convert the current flowing in the circuit into a current of a size that can be applied to an ammeter (not shown) of the control unit (240).

[0070] The current transformer (300) and the current transformer receiver (205) are provided in accordance with the number of phases. For example, if the AC current flowing in the circuit is three phases, i.e., R phase, S phase, and T phase, three current transformers (300) and three current transformer receivers (205) can be provided each.

[0071] An isolation groove (204) may be provided between each phase on the front side of the trip case (201). The isolation groove (204) increases the creepage distance, thereby improving the insulation performance between phases.

[0072] A voltage sensor insertion groove (215) is formed on the front of the trip unit case (201). A voltage sensor (not shown) is installed in the voltage sensor insertion groove (215). The voltage sensor senses the voltage generated in the connecting conductor (220) and transmits it to the control unit (240).

[0073] Referring further to Fig. 12, Fig. 12 illustrates a rear view of the electronic trip unit. Here, the transformer housing cover (210) has been removed. In addition, in the S phase, the power generation unit (350) of the transformer (300) has been removed. In the T phase, the connecting conductor (220) and the transformer (300) have been removed.

[0074] A connecting conductor (220) is provided at the center of the current transformer (300). The connecting conductor (220) connects the trip unit stator (198) connected to the power supply side and the load-side terminal (199) connected to the load side. The current transformer (300) reduces the current flowing through the connecting conductor (220) and sends it to the control unit (240).

[0075] A connecting conductor insertion portion (207) is formed protrudingly in the transformer housing (203). The connecting conductor insertion portion (207) is formed to extend forward and backward in the center of the transformer receiving portion (205). The connecting conductor insertion portion (207) is manufactured in a tube shape and has a connecting conductor insertion hole (208) formed therein. A connecting conductor (220) is inserted and installed in the connecting conductor insertion hole (208). A current transformer (300) is installed around the connecting conductor insertion portion (207).

[0076] The connecting conductor insert (207) is made of an insulating material. The connecting conductor insert (207) can be formed integrally with the transformer housing (203) using the same material. The transformer (300) and the connecting conductor (220) are insulated by the connecting conductor insert (207).

[0077] A connecting conductor (220) is installed in the trip unit (200) and electrically connects the power side and the load side. The current flowing in the connecting conductor (220) is measured by a current transformer so that a trip operation occurs when an abnormal current occurs.

[0078] The connecting conductor (220) has a connecting groove (222) formed on both sides for connecting the trip unit stator (198) or the load side terminal (199).

[0079] The trip unit stator (198) is connected to one end of the connecting conductor (220). The trip unit stator (198) connects the load-side fixed contact (112) and the load-side terminal (199) via the connecting conductor (220).

[0080] A transformer mounting portion (230) capable of fixing a transformer (300) around a connecting conductor insertion portion (207) is formed in the transformer housing (201). The transformer mounting portion (230) is formed to protrude from the bottom surface of the transformer receiving portion (205). The transformer mounting portion (230) may be formed in an overall circular shape.

[0081] Fig. 13 is a perspective view of a current transformer applied to an electronic trip unit of the present invention, Fig. 14 is an isolated perspective view of a current detection unit in Fig. 13, and Fig. 15 is an isolated perspective view of a power generation unit in Fig. 13.

[0082] The current transformer (300) is composed of a current detection unit (310) and a power generation unit (350).

[0083] The current detection unit (310) (or signal generation unit) includes a Rogowski coil (311), a first magnetic field absorbing material fixing member (320), and a first magnetic field absorbing material (330). The current detection unit (310) outputs a current signal to the control unit (240).

[0084] The Rogowski coil (311) is formed in a donut shape. The Rogowski coil (311) is formed by rolling the coil along the outer surface of the donut. Alternatively, the Rogowski coil can be manufactured by bending a long coil that is stretched in a straight line into a circular shape. Therefore, the Rogowski coil (311) is also called an air-core coil. The Rogowski coil (311) has the advantages of being small in size and having no saturation characteristics.

[0085] The Rogowski coil (311) is formed with a central hole. A connecting conductor (220) is inserted into a through hole (313) of the Rogowski coil (311). The Rogowski coil (311) senses the current flowing in the connecting conductor (220).

[0086] The first magnetic field absorber fixing member (320) is provided to support the first magnetic field absorber (330). The first magnetic field absorber fixing member (320) ensures that the first magnetic field absorber (330) is installed at a predetermined distance from the Rogowski coil (311). The first magnetic field absorber fixing member (320) mechanically supports the first magnetic field absorber (330) so that it is not deformed.

[0087] The first magnetic field absorber fixing member (320) is formed to a size that can wrap around the Rogowski coil (311). At this time, the first magnetic field absorber fixing member (320) is formed to be larger than the front diameter or the side width of the Rogowski coil (311). Accordingly, a space is formed between the Rogowski coil (311) and the first magnetic field absorber fixing member (320).

[0088] The first magnetic field absorbing material fixing member (320) is formed in an overall flat cylindrical shape.

[0089] The first magnetic field absorbing material fixing member (320) has a front portion (321) and a side portion (322) having a curved portion (323) and a flat portion (324).

[0090] A mounting hole (325) is formed in the center of the front portion (321) of the first magnetic field absorber fixing member (320). The mounting hole (325) occupies most of the area of ​​the front portion (321). Here, the mounting hole (325) is fitted into the transformer mounting portion (230).

[0091] The width of the front portion (321) of the first magnetic field absorber fixing member (320) excluding the mounting hole (325) is formed to be larger than the thickness of the Rogowski coil (311), and the width of the side portion (322) of the first magnetic field absorber fixing member (320) is formed to be larger than the width of the side portion of the Rogowski coil (311). Accordingly, the first magnetic field absorber fixing member (320) completely covers the Rogowski coil (311) from the front and side.

[0092] The inner diameter of the center hole (325) of the first magnetic field absorber fixing member (320) is formed smaller than the inner diameter of the Rogowski coil (311). Therefore, when the center hole (325) of the first magnetic field absorber fixing member (320) is fitted into the current transformer mounting portion (230) of the current transformer receiving portion (205), the Rogowski coil (311) is placed within the current transformer receiving portion (205) at a predetermined distance from the center hole (325).

[0093] An open groove (326) is formed in the flat portion (324) of the side portion (322). The open groove (326) is provided to prevent interference with surrounding components.

[0094] A work groove (327) having an inclined shape is provided on a portion of the curved surface (323) of the side surface (322) on the inner surface. The worker can adjust the position of the Rogowski coil (311) through the work groove (327) while the components of the current detection unit (310) are accommodated in the current transformer receiving unit (205) and are pre-assembled.

[0095] The first magnetic field absorbing material fixing member (320) has an open rear surface and can accommodate a Rogowski coil (311).

[0096] The first magnetic field absorber (330) is open at the front and back. Accordingly, the first magnetic field absorber (330) has a short tubular shape. The first magnetic field absorber (330) has a curved portion (323) and a flat portion (324) corresponding to the shape of the side portion (322) of the first magnetic field absorber fixing member (320). The first magnetic field absorber (330) covers the side portion of the Rogowski coil (311).

[0097] The first magnetic field absorber (330) is formed to surround the first magnetic field absorber fixing member (320). Since the Rogowski coil (311) is inserted inside the first magnetic field absorber fixing member (320), the first magnetic field absorber (330) surrounds the Rogowski coil (311) and absorbs the generated magnetic field.

[0098] The magnetic field absorber (330, 370) uses a material with high magnetic permeability. In other words, the material for the magnetic field absorber is a material that can well absorb the magnetic field (magnetic field) generated around the Rogowski coil (311). In electromagnetism, permeability is a value that indicates how much a medium is magnetized in a given magnetic field. The common symbol is the Greek letter μ. The international unit is henry per meter (H / m).

[0099] Using a material with high permeability as a magnetic absorber (330, 370) has the following implications.

[0100] First, the magnetic field absorber (330, 370) is easily magnetized. That is, magnetic induction occurs well and the magnetic flux density is high.

[0101] Second, it stores a lot of magnetic energy. In other words, it has a large magnetic energy storage capacity.

[0102] Third, the magnetic flux flows well. That is, the magnetic field flows well within the magnetic field absorber.

[0103] Due to this effect, the magnetic field generated in the Rogowski coil (311) is absorbed by the first magnetic field absorber (330) and prevented from spreading outward, thereby preventing it from affecting nearby phases.

[0104] Materials with high permeability such as permalloy or nano-crystalline can be used. Permalloy is an alloy of approximately 80% nickel and 20% iron, and is an excellent magnetic material with very high permeability and low magnetic hysteresis loss. Nano-crystalline has the characteristic of having a better permeability than permolloy, but it is fragile and requires caution when used.

[0105] As described above, the current detection unit (310) includes a Rogowski coil (311), a first magnetic field absorber fixing member (320), and a first magnetic field absorber (330). The Rogowski coil (311), the first magnetic field absorber fixing member (320), and the first magnetic field absorber (330) are combined by a molding method. For example, the Rogowski coil (311), the first magnetic field absorber fixing member (320), and the first magnetic field absorber (330) are inserted into the current transformer receiving unit (205), and in a pre-assembled state, a molding liquid such as epoxy resin is injected to solidify.

[0106] The center hole (325) of the first magnetic field absorbing material fixing member (320) is fitted into the transformer mounting portion (230) within the transformer receiving portion (205).

[0107] A first magnetic field absorber (330) is fitted on the outer surface of the first magnetic field absorber fixing member (320), and a Rogowski coil (311) is inserted into the interior of the first magnetic field absorber fixing member (320).

[0108] The power generation unit (350) generates current by the induced electromotive force of the iron core (351), and the control unit (240) is driven by the power using this current. In addition, the power generation unit (350) generates current by the induced electromotive force even in normal times, and the current generated at this time functions as a power source that enables the control unit (240) to be driven at all times.

[0109] The power generation unit (350) includes an iron core (351), a coil (360), and a second magnetic field absorber (370).

[0110] The core (351) can be made of cold-rolled grain-oriented silicon steel sheets. Multiple silicon steel sheets are bonded into multiple layers using a lap bonding method. The assembled steel sheets are wrapped with insulating tape with excellent thermal and mechanical properties, and the core surface is treated with an anti-corrosion coating to protect it.

[0111] A hollow portion (352) is formed in the center of the core (351), into which a connecting conductor (220) and a connecting conductor insertion portion (207) are inserted.

[0112] A coil (360) is formed in a part of the iron core (351). A current is generated in the coil (360) by electromagnetic induction.

[0113] When the rated current (several hundred amperes) flows within the small size of the circuit breaker for wiring, a magnetic field is generated around the bus bar of each phase, which distorts the output of the current detection unit (310) of the other phase.

[0114] Interphase interference, which distorts signals of different phases due to magnetic fields, has a negative impact on the measurement accuracy of a circuit breaker for wiring. Therefore, when implementing a high-precision measurement function in a circuit breaker, interphase interference must be minimized.

[0115] A second magnetic field absorber (370) is provided to prevent the influence of the magnetic field generated around the power generation unit (350) from reaching the adjacent phase.

[0116] The second magnetic field absorber (370) is formed in a shape that can wrap around the side surface of the iron core (351) and the coil (360).

[0117] The second magnetic field absorber (370) follows the characteristics and composition of the first magnetic field absorber (330). The second magnetic field absorber (370) may be formed of the same material as the first magnetic field absorber (330).

[0118] The control unit (240) operates on power provided from the power generation unit (350). If the control unit (240) determines that the current transmitted from the current detection unit (310) is an abnormal current, it operates a trip coil (not shown) to cut off the circuit.

[0119] According to an electronic trip unit of a circuit breaker for wiring according to one embodiment of the present invention, a magnetic field absorbing material is provided to wrap a Rogowski coil in a current detection unit, thereby preventing a magnetic field from spreading to an adjacent phase.

[0120] Additionally, a magnetic field absorbing material is provided to surround the iron core and coil in the power generating section to prevent the magnetic field from spreading to adjacent phases.

[0121] Accordingly, current measurement errors due to phase-to-phase interference when abnormal current occurs in the circuit are minimized.

[0122] Additionally, the interphase distance can be reduced because the interphase interference is prevented, thereby reducing the overall size.

[0123] The embodiments described above are illustrative of the best possible implementations of the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, these embodiments are not intended to limit the technical spirit of the present invention, but rather merely to illustrate it. Therefore, it should be understood that the scope of the technical spirit of the present invention is not limited by these embodiments. In other words, the scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included within the scope of the rights of the present invention.

[0124] [Explanation of symbols]

[0125] 100 Circuit Breaker

[0126] 200 electronic trip unit

[0127] 205 transformer receiving section

[0128] 220 connection conductor

[0129] 240 Control Unit

[0130] 300 transformer

[0131] 310 current detection unit

[0132] 311 Rogowski coil

[0133] 320 First magnetic field absorber fixing member

[0134] 330 First magnetic field absorber

[0135] 350 power generator

[0136] 351 iron core

[0137] 360 coil

[0138] 370 Second magnetic field absorber

Claims

1. In an electronic trip unit of a circuit breaker for wiring, in which a circuit is connected from the power side to the load side and an alternating current having multiple phases flows through the circuit, A current transformer is provided on each of the above plurality of phases to measure the alternating current, and the current transformer is It includes a current detection unit that measures the current of one of the phases on which the transformer is installed among the plurality of phases, An electronic trip unit of a circuit breaker for wiring, characterized in that the current detection unit is provided with a magnetic field absorbing material.

2. In paragraph 1, The above transformer is, An electronic trip unit of a circuit breaker for wiring, further comprising a power generation unit that generates voltage by induced electromotive force occurring in any one of the above phases.

3. In paragraph 2, An electronic trip unit of a wiring circuit breaker that operates by receiving power provided from the power generation unit and further includes a control unit that blocks the circuit when a current signal transmitted from the current detection unit is determined to be a fault current.

4. In paragraph 1, An electronic trip unit of a wiring circuit breaker, wherein a transformer receiving portion for receiving the current transformer is provided in a trip unit case forming an outer case of the electronic trip unit.

5. In paragraph 4, An electronic trip unit of a wiring circuit breaker, wherein a connecting conductor insertion portion in which a connecting conductor connected to the circuit is installed is provided in the above transformer receiving portion.

6. In paragraph 4, The above current detection unit includes a Rogowski coil having a through hole, An electronic trip unit of a circuit breaker for wiring, comprising a first magnetic field absorber wrapping the Rogowski coil among the above magnetic field absorbers.

7. In paragraph 6, The above current detection unit, An electronic trip unit of a circuit breaker for wiring, further comprising a first magnetic field absorbing material fixing member fixedly installed in the above-mentioned transformer receiving portion, accommodating the Rogowski coil inside, and having the first magnetic field absorbing material installed outside.

8. In paragraph 7, An electronic trip unit of a wiring circuit breaker, wherein a transformer mounting portion is formed protrudingly in the transformer receiving portion, and a center hole formed in the first magnetic field absorbing material fixing member to be fitted into the transformer mounting portion.

9. In paragraph 7, An electronic trip unit of a wiring circuit breaker, wherein the first magnetic field absorbing material fixing member has a front portion and a side portion, and the side portion has a curved portion and a flat portion.

10. In paragraph 8, An electronic trip unit of a wiring circuit breaker in which the inner diameter of the above-mentioned central hole is formed smaller than the inner diameter of the above-mentioned Rogowski coil.

11. In paragraph 9, An electronic trip unit of a wiring circuit breaker, wherein the width of the side portion of the first magnetic field absorbing material fixing member is formed to be larger than the width of the side portion of the Rogowski coil.

12. In paragraph 7, An electronic trip unit of a circuit breaker for wiring, wherein the above Rogowski coil, the first magnetic field absorber fixing member and the first magnetic field absorber are joined to each other by a molding method.

13. In paragraph 2, The above power generation unit, Contains iron core and coil, An electronic trip unit of a wiring circuit breaker having a second magnetic field absorbing material that surrounds the core and coil among the above magnetic field absorbing materials.

14. In paragraph 1, The above magnetic field absorbing material is an electronic trip unit of a circuit breaker formed of a material with high permeability.

15. In paragraph 14, The above magnetic field absorbing material is an electronic trip unit of a circuit breaker formed of permalloy or nano-crystalline.

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