JP7413975B2 - Overcurrent switch and electronic circuit breaker equipped with this overcurrent switch - Google Patents

Description

The present invention relates to an overcurrent switch and an electronic circuit breaker equipped with the overcurrent switch.

Conventional electronic circuit breakers are devices that detect, control, and issue tripping commands using electronic control, and are equipped with contacts in the current paths of each phase, as well as current transformers as current detection means. It is being When a current flows through the current path of each phase, a secondary current is induced on the secondary side of the current transformer, and the rectifier converts the secondary current into a direct current, converts it into a voltage signal, and inputs it to the control section. Then, when an overcurrent flows in the current path of each phase, the control section outputs a tripping signal according to the tripping operation characteristics (long time characteristic, short time characteristic, instantaneous characteristic), and outputs a trip signal when the trip signal is input. The removal electromagnetic device performs opening/closing operations of contacts arranged in the current path of each phase (for example, Patent Document 1).

Japanese Patent Application Publication No. 2011-258587

Incidentally, each current transformer, which is a current detection means of an electronic circuit breaker, has its own frequency gain characteristics due to variations in material properties, variations between production lots, and the like. For this reason, effective value accuracy can be expected for a certain limited range of frequencies, but the effective value accuracy decreases in frequency regions beyond that range, and there is a risk that the accuracy of the tripping operation characteristics of the control section will deteriorate. be. Therefore, if an attempt is made to widen the linear range by improving the frequency characteristics of a current transformer incorporated in an electronic circuit breaker, a problem arises in that the manufacturing cost increases.
Therefore, the present invention has been made to solve the above conventional problems, and provides an overcurrent switch that can obtain highly accurate and stable tripping operation characteristics, as well as a low-cost electronic circuit breaker. It is about providing the equipment.

In order to achieve the above object, an overcurrent switch according to one aspect of the present invention includes a contactor disposed in a current path, detects the current in the current path, and when an overcurrent flows, an electronic trip switch is provided. An overcurrent switch that opens a contact through a lead, and includes a heater connected to a current path and a temperature-sensitive operating mechanism component that is heated by the heater. There is a built-in temperature-sensitive ferrite that is placed near the switch and reed switch contact point and is manufactured to manage the Curie temperature. When the reed switch changes to an open contact or a closed contact, it outputs an operation signal to the electronic tripping section to open the contact , and the temperature-sensitive operating mechanism parts become temperature-sensitive. It is equipped with a ferrite, at least one permanent magnet, and a reed switch that is set as a normally closed contact or a normally open contact depending on the arrangement of the permanent magnet, and the temperature-sensitive ferrite reaches the Curie temperature due to the heat generated by the heater and becomes a non-magnetic material. When the temperature changes, the reed switch switches to a closed contact or an open contact, outputting an operation signal to open the contact to the electronic tripping section, and the heater also It is a coil-shaped heater placed in the coil-shaped heater, and the temperature-sensitive operating mechanism component is that the temperature-sensitive ferrite changes to a non-magnetic material due to heat generation in the coil-shaped heater due to overload current in the current path, and the reed switch opens or closes. By switching to the contact, it outputs an operation signal for long-time operation to open the contact to the electronic tripping section, and also reduces the induction generated in the coiled heater due to the short-circuit current in the current path or the instantaneous operating current. The magnetic field acts inside the temperature-sensitive operating mechanism parts, creating a magnetic saturation state, and the reed switch switches to an open contact or a closed contact, which causes the contact in the electronic tripping section to open, resulting in an instantaneous operation. Now outputs a signal.
Moreover, in the electronic circuit breaker according to one aspect of the present invention, the above-described overcurrent switch is connected in series to a current transformer connected to the current path as a current detection means.

The overcurrent switch according to the present invention can obtain highly accurate and stable tripping operation characteristics. Further, the electronic circuit breaker according to the present invention can obtain highly accurate and stable tripping operation characteristics regardless of the frequency gain characteristics of the current transformer, and therefore can reduce costs.

1 is a block diagram showing an analog electronic overcurrent switch and circuit breaker according to a first embodiment of the present invention; FIG. It is a figure which shows the tripping operation characteristic of a circuit breaker. FIG. 3 is a diagram showing an overcurrent switch incorporated in the analog electronic circuit breaker of the first embodiment. FIG. 6 is a diagram illustrating a second embodiment of an overcurrent switch that can be incorporated into an analog electronic circuit breaker. It is a block diagram which shows the analog electronic circuit breaker of 3rd Embodiment based on this invention. It is a figure which shows the overcurrent switch incorporated in the analog electronic circuit breaker of 3rd Embodiment. FIG. 7 is a diagram showing a fourth embodiment of an overcurrent switch that can be incorporated into an analog electronic circuit breaker. It is a block diagram which shows the digital electronic circuit breaker of 5th Embodiment based on this invention.

Next, embodiments according to the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar symbols. However, it should be noted that the drawings are schematic and the relationship between thickness and planar dimensions, the ratio of the thickness of each layer, etc. are different from reality. Therefore, the specific thickness and dimensions should be determined with reference to the following explanation. Furthermore, it goes without saying that the drawings include portions with different dimensional relationships and ratios.

In addition, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention. etc. are not specified as those listed below. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.

[First embodiment]
1 to 3 show a first embodiment of an analog electronic circuit breaker 50 according to the present invention.
FIG. 1 is a block diagram illustrating an analog electronic circuit breaker 50. As shown in FIG. In the circuit breaker 50 of this embodiment, the current flowing through the main circuit 71 is detected as a current signal by the current transformer 72, the maximum value of the three phases is rectified by the rectifier circuit 73, and then the current is detected by the current-voltage conversion circuit 74. converted into a voltage signal. The voltage signal converted by the current-voltage conversion circuit 74 is input to the short time limit circuit 76 via the effective value detection circuit 75, and the trigger circuit 77 is activated after a predetermined delay time depending on the magnitude of the effective value.

The trigger circuit 77 excites the tripping electromagnetic device 81 and opens the movable contact (not shown) of the movable contact 51 from the fixed contact (not shown) of the fixed contact 52 via the opening/closing mechanism (not shown). let Note that the output current of the rectifier circuit 73 is supplied to the overcurrent switch 78 and each circuit via the power supply circuit 83.
The overcurrent switch 78 is connected to the main circuit 71 in series with the current transformer 72, and the overcurrent switch 78 is connected to a long time limit circuit 79. The long time limit circuit 79 operates the trigger circuit 77 after a predetermined delay time when the overcurrent switch 78 detects an overload current.
Further, the voltage signal of the current-voltage conversion circuit 74 is also input to the instantaneous circuit 80, and when the voltage signal exceeds a predetermined value, the trigger circuit 77 is activated.

The overcurrent switch 78 of this embodiment operates the trigger circuit 77 according to the long time characteristic of the tripping operation characteristic shown in FIG. That is, when an overload current exceeding the rated current flows through the main circuit 71, the overcurrent switch 78 outputs an output signal to the long time limit circuit 79, and the long time limit circuit 79 outputs an operation signal to the trigger circuit 77. .
In this embodiment, when a current exceeding the overload current flows through the main circuit 71, the short time limit circuit 76 outputs an operation signal to the trigger circuit 77. Further, when a short circuit current flows through the main circuit 71, the instantaneous circuit 80 outputs an operation signal to the trigger circuit 77.

FIG. 3 shows an overcurrent switch 78 connected to the main circuit 71, which is arranged so as to be wrapped around the outer periphery of a temperature-sensing operating mechanism component 85 and a switch case 91 that constitutes the temperature-sensing operating mechanism component 85. It is composed of a coil-shaped heater 86.
The temperature-sensitive operating mechanism component 85 includes a reed switch 87 , an annular temperature-sensitive ferrite 88 that is arranged to cover the outer periphery of a pair of contacts (not shown) of the reed switch 87 , and a ring-shaped temperature-sensitive ferrite 88 that covers the outer periphery of a pair of contacts (not shown) of the reed switch 87 . A first annular permanent magnet 89 is disposed adjacent to one end of the temperature-sensitive ferrite 88; It includes a second permanent magnet 90, a non-magnetic cylindrical switch case 91 that holds a temperature-sensitive ferrite 88, and first and second permanent magnets 89, 90.

The first permanent magnet 89 and the second permanent magnet 90 are arranged so as to be magnetized in the same direction.
The temperature-sensitive ferrite 88 is a ferrite-based magnetic material that is a soft magnetic material when the temperature is below the Curie temperature, and changes to a non-magnetic material when heated above the Curie temperature.
The Curie temperature of the temperature-sensitive ferrite 88 is determined by the temperature-sensitive ferrite 88 changing into a non-magnetic material due to heat conduction when an overload current (for example, 200% A or more of the rated current) flows through the coil-shaped heater 86 and generates heat. temperature is set.

When the temperature-sensitive ferrite 88 is a magnetic material, a magnetic field is generated that passes through the first permanent magnet 89, the temperature-sensitive ferrite 88, and the second permanent magnet 90. This magnetic field also acts on the reed switch 87, one of the pair of contacts of the reed switch 87 becomes the N pole, the other of the pair of contacts becomes the S pole, the pair of contacts are magnetically attracted, and the reed switch 87 is normally closed. It is considered a point of contact.
One end 87a of the normally closed reed switch 87 is connected to the power supply circuit 83, and the other end 87b is connected to the long time limit circuit 79, as shown in FIG.

Next, the operation of the analog electronic circuit breaker 50 of the first embodiment will be explained.
The circuit breaker 50 closes the movable contact of the movable contactor 51 and the fixed contact of the fixed contactor 52 by the opening/closing mechanism section, and a rated current flows through the main circuit 71 to make it energized.
At this time, the temperature-sensitive ferrite 88 of the temperature-sensitive operating mechanism component 85 has changed into a magnetic material because the temperature below the Curie temperature is conducted from the coil-shaped heater 86 through which the rated current flows. Therefore, in the initial state of the temperature-sensitive operating mechanism component 85, the reed switch 87 is a normally closed contact, and the long time limit circuit 79 through which current flows from the normally closed reed switch 87, the overcurrent switch 78 detects an overcurrent. If not, no operation signal is output to the trigger circuit 77.

When an overload current flows through the main circuit 71, a temperature higher than the Curie temperature is conducted from the coiled heater 86, so that the temperature-sensitive ferrite 88 changes into a non-magnetic material. Since all the parts of the temperature-sensitive operation mechanism part 85 have heat capacities, there is a delay time until the temperature-sensitive ferrite 88 reaches the Curie temperature. This delay time is the same as the long-time operation, and an overload current flows through the energizing path, and the time for the long-time operation can be set by setting the heat capacity of the temperature-sensitive operation mechanism component 85.
As the temperature-sensitive ferrite 88 of the temperature-sensitive operation mechanism component 85 changes to a non-magnetic material, the magnetic field passing through the first permanent magnet 89, temperature-sensitive ferrite 88, and second permanent magnet 90 disappears, and acts on the reed switch 87. The magnetic flux decreases, and the pair of contacts of the reed switch 87 become open contacts due to the reed elastic force.

In this way, when an overload current flows through the coil-shaped heater 86 of the overcurrent switch 78, the reed switch 87 becomes an open contact, and the long time limit circuit 79 is triggered as if the overcurrent switch 78 has detected an overcurrent. An operating signal is output to the circuit 77. The trigger circuit 77 excites the tripping electromagnetic device 81, and opens the movable contact of the movable contact 51 from the fixed contact of the fixed contact 52 via the opening/closing mechanism section (long-time tripping operation).

Further, when an overload current having a short time limit characteristic flows through the main circuit 71, the voltage signal converted by the current-voltage conversion circuit 74 is input from the effective value detection circuit 75 to the short time limit circuit 76, and the short time limit circuit 76 , an operation signal is output to the trigger circuit 77 assuming that an overload current having a short time limit characteristic is flowing. The trigger circuit 77 excites the tripping electromagnetic device 81 and opens the movable contact of the movable contact 51 from the fixed contact of the fixed contact 52 via the opening/closing mechanism (short-time tripping operation).

Further, when a short circuit current flows through the main circuit 71, the voltage signal converted by the current-voltage conversion circuit 74 is input to the instantaneous circuit 80, and the instantaneous circuit 80 assumes that a short circuit current is flowing and outputs the voltage signal to the trigger circuit 77. Outputs an operation signal. The trigger circuit 77 excites the tripping electromagnetic device 81 and causes the movable contact of the movable contact 51 to open from the fixed contact of the fixed contact 52 via the switching mechanism section 7 (instantaneous tripping operation).

Next, the effects of this embodiment will be explained.
In the overcurrent switch 78 incorporated in the circuit breaker 50 of this embodiment, when an overload current flows through the coil-shaped heater 86, the temperature-sensitive ferrite 88 changes to a non-magnetic material, and the normally closed reed switch 87 becomes an open contact, and the overcurrent switch 78 outputs an operation signal for the trigger circuit 77 to the long time limit circuit 79, assuming that the overcurrent has been detected. In this way, the circuit breaker 50 of this embodiment can obtain stable tripping operation characteristics because the overcurrent switch 78 performs the long time operation with high precision. Further, since there is no need to improve the frequency characteristics of the current transformer 72 connected in series to the main circuit 71 together with the overcurrent switch 78, a low-cost circuit breaker 50 can be provided.
Further, the time delay of the overcurrent switch 78 of this embodiment can be determined by changing the amount of heat generated by the coiled heater 86 and the thickness and size of the first and second permanent magnets 89 and 90 and the temperature-sensitive ferrite 88. It can be adjusted freely by simply changing the heat capacity.

[Second embodiment]
Next, FIG. 4 shows an overcurrent switch 95 according to a second embodiment of the present invention.
The overcurrent switch 95 of this embodiment is arranged in place of the overcurrent switch 78 of the first embodiment shown in FIG. 1, and the reed switch 87 of the overcurrent switch 78 of the first embodiment is normally closed. Although it is a contact switch, the reed switch 98 that constitutes the overcurrent switch 95 of this embodiment is a normally open contact switch.
The overcurrent switch 95 of this embodiment includes a temperature-sensitive operating mechanism component 96 and a coil-shaped heater 97 that is arranged to be wound around the outer periphery of the temperature-sensitive operating mechanism component 96.

The temperature-sensitive operating mechanism component 96 includes a reed switch 98, an annular spacer 99 made of a non-magnetic material disposed around the outer periphery near a pair of contacts (not shown) of the reed switch 98, and an annular spacer 99 adjacent to one end of the spacer 99. an annular first temperature-sensitive ferrite 100 disposed as shown in FIG. a first annular permanent magnet 102 disposed adjacent to the ferrite 100; a second annular permanent magnet 103 disposed adjacent to the second temperature-sensitive ferrite 101 on the opposite side to the spacer 99; It includes a switch case 104 that houses a spacer 99, a first temperature-sensitive ferrite 100, a second temperature-sensitive ferrite 101, a first permanent magnet 102, and a second permanent magnet 103.

The first permanent magnet 102 and the second permanent magnet 103 are arranged with their magnetization directed in the same direction.
The first temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 are ferrite-based magnetic materials that are soft magnetic when the temperature is below the Curie temperature, and change to non-magnetic when heated above the Curie temperature. It is.
The Curie temperature of the first temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 is determined by heat conduction when an overload current flows through the coil-shaped heater 97 and generates heat. The temperature is set at which the material changes to a non-magnetic material.

When the first temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 are magnetic, a magnetic field is generated that passes through the first permanent magnet 102 and the first temperature-sensitive ferrite 100, and the second permanent magnet 103 and the second temperature-sensitive ferrite 101 are magnetic. Another magnetic field is generated that passes through the warm ferrite 101. Therefore, the magnetic flux acting on the reed switch 98 is reduced, so the pair of contacts of the reed switch 98 become open contacts due to the reed elastic force, and the reed switch 98 becomes a normally open contact.
Furthermore, when the first temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 become non-magnetic, a magnetic field is generated only by the first permanent magnet 102, and another magnetic field is generated only by the second permanent magnet 103. Therefore, these magnetic fields act on the reed switch 98, one of the pair of contacts of the reed switch 98 becomes the north pole, the other of the pair of contacts becomes the south pole, and the pair of contacts are magnetically attracted, and the reed switch 98 A pair of contacts are in a closed state.

When the temperature sensing mechanism component 96 of this embodiment is placed in place of the temperature sensing mechanism component 85 of the overcurrent switch 78 shown in FIG. In this case, since the first temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 have changed to magnetic materials, the reed switch 98 becomes an open contact in the initial state of the temperature-sensitive operating mechanism component 85. The long time limit circuit 79 of the present embodiment does not output an operation signal to the trigger circuit 77 when no current flows from the reed switch 98, assuming that the overcurrent switch 95 has not detected an overcurrent.

Furthermore, when an overload current flows through the main circuit 71, the high temperature heat generated by the coil-shaped heater 97 is transmitted to the first temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 via the switch case 104, and the The temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 are heated to the Curie temperature and change into non-magnetic materials.
In the temperature-sensitive operating mechanism component 96, the first temperature-sensitive ferrite 100 and the second temperature-sensitive ferrite 101 become non-magnetic, so that the pair of contacts of the reed switch 98 are closed. Then, the long time limit circuit 79 of this embodiment outputs an operation signal to the trigger circuit 77, assuming that the current flowing from the reed switch 98 indicates that the overcurrent switch 95 has detected an overcurrent.
Although the reed switch 98 constituting the overcurrent switch 95 of this embodiment is a normally open contact, it can produce the same effects as the fourteenth embodiment.

[Third embodiment]
Next, FIGS. 5 and 6 show an analog electronic circuit breaker 50 according to a third embodiment of the present invention. Note that the same components as those of the circuit breaker 50 of the first embodiment shown in FIG.
In this embodiment, an overcurrent switch 111 is connected to the main circuit 71 in series with a current transformer 72 . A long time/instantaneous circuit 108 is connected to the overcurrent switch 111, and when the overcurrent switch 111 detects an overload current or a short circuit current and operates, the long time/instantaneous circuit 108 operates the trigger circuit 77. let Note that in the circuit breaker 50 of this embodiment, the instantaneous circuit 80 shown in the first embodiment of FIG. 1 is not disposed between the current-voltage conversion circuit 74 and the trigger circuit 77.

As shown in FIG. 6, the overcurrent switch 111 includes a temperature-sensing operating mechanism component 112 and a coil-shaped heater 113 that is arranged around the outer periphery of a switch case 120 that constitutes the temperature-sensing operating mechanism component 112. It is equipped with.
The temperature-sensitive operating mechanism component 112 includes a reed switch 114, an annular temperature-sensitive ferrite 115 disposed covering the outer periphery of a pair of contacts (not shown) of the reed switch 114, and a ring-shaped temperature-sensitive ferrite 115 disposed on the outer periphery of one end of the reed switch 114. A first annular magnetic yoke 116 having magnetism disposed adjacent to one end of the temperature-sensitive ferrite 115, a first permanent magnet 117 disposed at one end adjacent to the first magnetic yoke 116, and a reed switch. A second annular magnetic yoke 118 having magnetism is arranged adjacent to the other end of the temperature-sensitive ferrite 115 on the outer periphery of the other end of the temperature-sensitive ferrite 114; a non-magnetic cylindrical switch case 120 that holds a temperature-sensitive ferrite 115, first and second magnetic yokes 116, 118, and first and second permanent magnets 117, 119. ing.

The first permanent magnet 117 and the second permanent magnet 119 are arranged with their magnetization directed in the same direction.
The temperature-sensitive ferrite 115 is a ferrite-based magnetic material that is a soft magnetic material when the temperature is below the Curie temperature, and changes to a non-magnetic material when heated above the Curie temperature. The Curie temperature of the temperature-sensitive ferrite 115 is set to a temperature at which the temperature-sensitive ferrite 115 changes into a non-magnetic material due to heat conduction when an overload current flows through the coil-shaped heater 113 and generates heat.

When the temperature-sensitive ferrite 115 is a magnetic material, a magnetic field is generated that passes through the first permanent magnet 117, the first magnetic yoke 116, the temperature-sensitive ferrite 115, the second magnetic yoke 118, and the second permanent magnet 119. This magnetic field also acts on the reed switch 114, one of the pair of contacts of the reed switch 114 becomes the north pole, the other of the pair of contacts becomes the south pole, the pair of contacts are magnetically attracted, and the reed switch 114 is normally closed. It is considered a point of contact. One end 114a of the reed switch 114 is connected to the power supply circuit 83 of FIG. 5, and the other end 114b is connected to the long time/instantaneous circuit 108.

Next, the operation of the circuit breaker 50 of the third embodiment will be explained.
The circuit breaker 50 closes the movable contact of the movable contactor 51 and the fixed contact of the fixed contactor 52 by the opening/closing mechanism section, and a rated current flows through the main circuit 71 to make it energized.
At this time, the temperature-sensitive ferrite 115 of the temperature-sensitive operating mechanism component 112 has changed into a magnetic material because a temperature lower than the Curie temperature is conducted from the coil-shaped heater 113 through which the rated current is flowing. Therefore, in the initial state of the temperature-sensitive operating mechanism component 112, the reed switch 114 is a closed contact, and the long-time/instantaneous circuit 108 through which current flows from the reed switch 114 has no overcurrent detected by the overcurrent switch 111. As a result, no operation signal is output to the trigger circuit 77.

When an overload current flows through the main circuit 71, a temperature higher than the Curie temperature is conducted from the coiled heater 113, so the temperature-sensitive ferrite 115 changes into a non-magnetic material. The temperature-sensitive operation mechanism component 112 has a first permanent magnet 117, a first magnetic yoke 116, a temperature-sensitive ferrite 115, a second magnetic yoke 118, and a second permanent magnet 119 by changing the temperature-sensitive ferrite 115 into a non-magnetic material. Since there is no passing magnetic field and the magnetic flux acting on the reed switch 114 is reduced, the pair of contacts of the reed switch 114 become open contacts due to the reed elastic force.

In this way, when an overload current flows through the coil-shaped heater 113 of the overcurrent switch 111, the reed switch 114 becomes an open contact, and the long time/instantaneous circuit 108 assumes that the overcurrent switch 111 has detected an overcurrent. , outputs an operation signal to the trigger circuit 77. The trigger circuit 77 excites the tripping electromagnetic device 81, and opens the movable contact of the movable contact 51 from the fixed contact of the fixed contact 52 via the opening/closing mechanism section (long-time tripping operation). Here, since all the parts of the temperature-sensitive operation mechanism part 112 have heat capacities, there is a delay time until the temperature-sensitive ferrite 115 reaches the Curie temperature. This delay time is the same as the long-time operation, and an overload current flows through the energizing path, and the time for the long-time operation can be set by setting the heat capacity of the temperature-sensitive operation mechanism component 112.

Further, when an overload current having a short time limit characteristic flows through the main circuit 71, the voltage signal converted by the current-voltage conversion circuit 74 is input from the effective value detection circuit 75 to the short time limit circuit 76, and the short time limit circuit 76 , an operation signal is output to the trigger circuit 77 assuming that an overload current having a short time limit characteristic is flowing. The trigger circuit 77 excites the tripping electromagnetic device 81 and opens the movable contact of the movable contact 51 from the fixed contact of the fixed contact 52 via the opening/closing mechanism (short-time tripping operation).

Further, when a short circuit current flows through the main circuit 71, an induced electromagnetic field DM is generated around the coil-shaped heater 113, as shown in FIG. This induced electromagnetic field DM acts in the direction of canceling the magnetic field passing through the first permanent magnet 117, first magnetic yoke 116, temperature-sensitive ferrite 115, second magnetic yoke 118, and second permanent magnet 119 of the temperature-sensitive operation mechanism component 112. Therefore, the magnetic forces of the first magnetic yoke 116 and the second magnetic yoke 118 are saturated, and the magnetic force transmitted to the temperature-sensitive ferrite 115 is reduced, and the magnetic flux acting on the reed switch 114 is reduced, so that the pair of contacts of the reed switch 114 is becomes an open contact due to lead elastic force. As described above, when a short-circuit current flows through the main circuit 71 and an induced electromagnetic field DM is generated around the coil-shaped heater 113 of the overcurrent switch 111, the reed switch 114 becomes an open contact. The long time/instantaneous circuit 108 in which no current flows from the reed switch 114 outputs an operation signal to the trigger circuit 77 assuming that a short circuit current is flowing. The trigger circuit 77 excites the tripping electromagnetic device 81, and causes the movable contact of the movable contact 51 to open from the fixed contact of the fixed contact 52 via the opening/closing mechanism (instantaneous tripping operation).

Next, the effects of this embodiment will be explained.
In the overcurrent switch 111 incorporated in the circuit breaker 50 of the third embodiment, the heated temperature-sensitive ferrite 115 changes into a non-magnetic material when an overload current flows through the coil-shaped heater 113. The magnetic field passing through the permanent magnet 117, the first magnetic yoke 116, the temperature-sensitive ferrite 115, the second magnetic yoke 118, and the second permanent magnet 119 disappears, and the magnetic flux acting on the reed switch 114 decreases, so the reed switch 114 is opened. It becomes a point of contact. Furthermore, when a short-circuit current flows through the main circuit 71, an induced electromagnetic field DM generated around the coil-shaped heater 113 is transmitted to the first permanent magnet 117, the first magnetic yoke 116, and the temperature-sensitive ferrite 115 of the temperature-sensitive operating mechanism component 112. , acts in the direction of canceling the magnetic field passing through the second magnetic yoke 118 and the second permanent magnet 119, so the magnetic force of the first magnetic yoke 116 and the second magnetic yoke 118 is saturated and the magnetic force transmitted to the temperature-sensitive ferrite 115 is reduced. Then, the reed switch 114 becomes an open contact. The long time/instantaneous circuit 108 detects the open contact of the reed switch 114 and outputs an operation signal to the trigger circuit 77, assuming that the overcurrent switch 111 has detected an overload current or short circuit current having long time characteristics.

Therefore, in the circuit breaker 50 of this embodiment, the overcurrent switch 111 performs long-time operation and instantaneous operation with high precision, so that stable tripping operation can be obtained. Further, since there is no need to improve the frequency characteristics of the current transformer 72 connected in series to the main circuit 71 together with the overcurrent switch 111, a low-cost circuit breaker 50 can be provided.
Further, the time delay of the long-time operation of the overcurrent switch 111 of this embodiment depends on the amount of heat generated by the coiled heater 113, the first magnetic yoke 116, the first permanent magnet 117, the second magnetic yoke 118, the second It can be freely adjusted by simply changing the heat capacity by changing the thickness and size of the permanent magnet 119 and the switch case 120.

[Fourth embodiment]
Next, FIG. 7 shows an overcurrent switch 130 according to a fourth embodiment of the present invention.
The overcurrent switch 130 of this embodiment is arranged in place of the overcurrent switch 111 shown in FIG. 5, and the reed switch 114 of the overcurrent switch 111 of FIG. 5 is a normally closed contact. The reed switch 133 constituting the overcurrent switch 130 of this embodiment is a normally open contact.
The overcurrent switch 130 of this embodiment includes a temperature-sensitive operating mechanism component 131 and a coil-shaped heater 132 that is arranged to be wrapped around the outer periphery of a switch case 141 that constitutes the temperature-sensitive operating mechanism component 131. We are prepared.

The temperature-sensitive operating mechanism component 131 includes a reed switch 133, an annular spacer 134 made of a non-magnetic material disposed around the outer periphery near a pair of contacts (not shown) of the reed switch 133, and an annular spacer 134 adjacent to one end of the spacer 134. an annular first temperature-sensitive ferrite 135 disposed as shown in FIG. A first annular magnetic yoke 137 having magnetism is disposed adjacent to the ferrite 135; a second magnetic yoke 138; a first annular permanent magnet 139 disposed adjacent to the first magnetic yoke 137; and a second annular permanent magnet 140 disposed adjacent to the second magnetic yoke 138. It includes a switch case 141 that houses a spacer 134, first and second temperature-sensitive ferrites 135 and 136, first and second magnetic yokes 137 and 138, and first and second permanent magnets 139 and 140.

The first permanent magnet 139 and the second permanent magnet 140 are arranged with their magnetization directed in the same direction.
The first temperature-sensitive ferrite 135 and the second temperature-sensitive ferrite 136 are ferrite-based magnetic materials that are soft magnetic when the temperature is below the Curie temperature, and change to non-magnetic when heated above the Curie temperature. It is. The Curie temperature of the first temperature-sensitive ferrite 135 and the second temperature-sensing ferrite 136 is determined by thermal conduction when an overload current flows through the coil-shaped heater 132 and generates heat. The temperature is set at which the material changes to a non-magnetic material.

When the first temperature-sensitive ferrite 135 and the second temperature-sensitive ferrite 136 are magnetic, a magnetic field is generated that passes through the first permanent magnet 139, the first magnetic yoke 137, and the first temperature-sensitive ferrite 135. Another magnetic field is also generated that passes through the two permanent magnets 140, the second magnetic yoke 138, and the second temperature-sensitive ferrite 136. Therefore, the magnetic flux acting on the reed switch 133 decreases, so that the pair of contacts of the reed switch 133 become open contacts due to the reed elastic force (normally open contacts).

Further, when the first temperature-sensitive ferrite 135 and the second temperature-sensitive ferrite 136 become non-magnetic, a magnetic field is generated by the first permanent magnet 139 and the first magnetic yoke 137, and the second permanent magnet 140 and the second magnetic yoke 138 generate a magnetic field. Another magnetic field is also generated. Therefore, these magnetic fields act on the reed switch 133, one of the pair of contacts of the reed switch 133 becomes the north pole, the other of the pair of contacts becomes the south pole, and the pair of contacts are magnetically attracted, and the reed switch 133 A pair of contacts are in a closed state.

When the overcurrent switch 130 of this embodiment is arranged in place of the overcurrent switch 111 shown in FIG. Since the warm ferrite 135 and the second temperature-sensitive ferrite 136 have been changed into magnetic materials, the reed switch 133 of the temperature-sensitive operating mechanism component 131 becomes a normally open contact. Then, the long time/instantaneous circuit 108 does not output an operation signal to the trigger circuit 77, assuming that the overcurrent switch 130 has not detected an overcurrent when no current flows from the reed switch 133.

Furthermore, when an overload current with long time-limiting characteristics flows through the main circuit 71, the high temperature heat generated by the coil-shaped heater 132 is transferred to the first temperature-sensitive ferrite 135 and the second temperature-sensitive ferrite 136 via the switch case 141. The first temperature-sensitive ferrite 135 and the second temperature-sensitive ferrite 136 are heated to the Curie temperature and changed into a non-magnetic material.
In the temperature sensing operation mechanism component 131, the reed switch 133 is brought into a closed state when the first temperature sensing ferrite 135 and the second temperature sensing ferrite 136 become non-magnetic. Then, the long time/instantaneous circuit 108 outputs an operation signal to the trigger circuit 77, regarding the state in which current flows from the reed switch 133 as an overcurrent detected by the overcurrent switch 130.

Furthermore, when a short circuit current flows through the main circuit 71, an induced electromagnetic field DM is generated around the coil-shaped heater 132, as shown in FIG. This induced electromagnetic field DM is a magnetic field that passes through the first permanent magnet 139, the first magnetic yoke 137, and the first temperature-sensitive ferrite 135, which is a magnetic material, and the second permanent magnet 140, the second magnetic yoke 138, and the magnetic material. It acts in a direction to cancel the magnetic field passing through the second temperature-sensitive ferrite 136. Therefore, the magnetic force of the first permanent magnet 139 and the first magnetic yoke 137 is saturated, the magnetic force transmitted to the first temperature-sensitive ferrite 135 is reduced, and the magnetic force of the second permanent magnet 140 and the second magnetic yoke 138 is saturated. Since the magnetic force transmitted to the second temperature-sensitive ferrite 136 is reduced and the magnetic flux acting on the reed switch 133 is reduced, the pair of contacts of the reed switch 133 become open contacts due to the reed elastic force. As described above, when a short circuit current flows through the main circuit 71 and an induced electromagnetic field DM is generated around the coil-shaped heater 132 of the overcurrent switch 130, the reed switch 133 becomes an open contact. The long time/instantaneous circuit 108 in which no current flows from the reed switch 133 outputs an operation signal to the trigger circuit 77 assuming that a short circuit current is flowing.
Therefore, although the reed switch 133 constituting the overcurrent switch 130 of this embodiment is a normally open contact, it can produce the same effects as the third embodiment.

[Fifth embodiment]
Next, FIG. 8 shows a digital electronic circuit breaker 50 according to a fifth embodiment of the present invention.
In the digital electronic circuit breaker 50 of this embodiment, the current flowing through the main circuit 71 is detected as a current signal by the current transformer 72, and after the maximum value of the three phases is rectified by the rectifier circuit 73, the current-voltage The conversion circuit 74 converts it into a voltage signal. The voltage signal converted by the current-voltage conversion circuit 74 is amplified by the amplifier circuit 151, and its output signal is input to a microcontroller 152 configured using a microcomputer.

In addition, the overcurrent switch 78 of the first embodiment shown in FIGS. 1 to 3 is connected to the main circuit 71 in series with the current transformer 72, and the switch operation circuit 153 is connected to the overcurrent switch 78. has been done. Note that the output current of the rectifier circuit 73 is supplied to the amplifier circuit 151, microcontroller 152, overcurrent switch 78, and drive section 154 via a current-voltage conversion circuit 74.
In the overcurrent switch 78, when the rated current flows through the coiled heater 86, the reed switch 87 is a normally closed contact, and when an overload current flows through the coiled heater 86, the reed switch 87 is an open contact. becomes. The switch operation circuit 153 outputs an output signal corresponding to the opening/closing operation of the reed switch 87 to the microcontroller 152.

The microcontroller 152 executes a predetermined program in accordance with the tripping operation characteristics shown in FIG. 2, and outputs a tripping signal to the drive unit 154 made of a thyristor or a transistor.
That is, when the microcontroller 152 determines that the current in the main circuit 71 has exceeded the rated current and increased to an overload current based on the output signal from the switch operation circuit 153, it outputs a tripping signal to the drive unit 154. The tripping electromagnetic device 81 to which the tripping signal is input opens the movable contact of the movable contactor 51 from the fixed contact of the fixed contactor 52 (long-time operation).

Furthermore, when the microcontroller 152 determines that the current in the main circuit 71 has exceeded the rated current and increased to an overload current having short-time characteristics or a short-circuit current based on the output signal from the amplifier circuit 151, the microcontroller 152 activates the drive unit 154. Outputs a tripping signal (short-time operation).
Therefore, in the digital electronic circuit breaker 50 of this embodiment, since the overcurrent switch 78 performs a long-time operation with high precision, stable tripping operation characteristics can be obtained. Further, since there is no need to improve the frequency characteristics of the current transformer 72 connected in series to the main circuit 71 together with the overcurrent switch 78, a low-cost circuit breaker 50 can be provided.

Further, the time delay of the overcurrent switch 78 of this embodiment can be determined by changing the amount of heat generated by the coiled heater 86 and the thickness and size of the first and second permanent magnets 89 and 90 and the temperature-sensitive ferrite 88. It can be adjusted freely by simply changing the heat capacity.
Note that even if the normally open contact overcurrent switch 95 of the second embodiment shown in FIG. 4 is connected to the main circuit 71 in place of the overcurrent switch 78 of the first embodiment, the same effects can be obtained. Can be done.

Furthermore, in place of the overcurrent switch 78 of the first embodiment, the overcurrent switch 111 of the third embodiment shown in FIG. 6 or the overcurrent switch 130 of the fourth embodiment shown in FIG. 7 is used in the main circuit 71. may be connected. In this case, the switch operation circuit 153 is a circuit that causes the microcontroller 152 to output a tripping signal to the drive section 154 when an overload current having a long time limit characteristic or a short circuit current flows in the main circuit 71. shall be.

50 Circuit breaker 51 Movable contact 52 Fixed contact 71 Main circuit (current path)
72 Current transformer 73 Rectifier circuit 74 Voltage conversion circuit 75 Effective value detection circuit 76 Short time limit circuit 77 Trigger circuit 78 Overcurrent switch 79 Long time limit circuit 80 Instantaneous circuit 81 Tripping electromagnetic device (electronic tripping unit)
83 Power supply circuit 85 Temperature sensing operating mechanism parts 86 Coiled heater 87 Reed switch 87a One end of reed switch 87b Other end of reed switch 88 Temperature sensing ferrite 89 First permanent magnet 90 Second permanent magnet 91 Switch case 95 Overcurrent switch 96 Temperature sensing operating mechanism parts 97 Coiled heater 98 Reed switch 99 Spacer 100 First temperature sensing ferrite 101 Second temperature sensing ferrite 102 First permanent magnet 103 Second permanent magnet 104 Switch case 108 Long time/instantaneous circuit 111 Overcurrent switch 112 Temperature sensing operating mechanism parts 113 Coiled heater 114 Reed switch 114a One end of reed switch 114b Other end of reed switch 115 Temperature sensing ferrite 116 First magnetic yoke 117 First permanent magnet 118 Second magnetic yoke 119 Second permanent magnet 120 Switch case 130 Overcurrent switch 133 Reed switch 131 Temperature-sensitive operating mechanism parts 141 Switch case 132 Coiled heater 134 Spacer 135 First temperature-sensitive ferrite 136 Second temperature-sensitive ferrite 137 First magnetic yoke 138 Second magnetic yoke 139 First Permanent magnet 140 Second permanent magnet 141 Switch case 151 Amplifier circuit 152 Microcontroller 153 Switch operation circuit

Claims (3)

An overcurrent switch in which a contactor is arranged in a current path, and when an overcurrent flows by detecting a current in the current path, the contactor is opened through an electronic tripping part,
comprising a heater connected to the current path and a temperature-sensitive operating mechanism component heated by the heater,
The temperature-sensitive operating mechanism component includes a reed switch and a temperature-sensitive ferrite disposed near a contact point of the reed switch,
The temperature-sensitive ferrite changes into a non-magnetic material when the temperature reaches the Curie temperature due to heat generated by the heater due to an overcurrent in the current path, and the reed switch switches to an open contact or a closed contact, so that the electronic type outputting an operation signal to the tripping part to open the contact;
The temperature-sensitive operating mechanism component includes the temperature-sensitive ferrite, at least one permanent magnet, and the reed switch set to a normally closed contact or a normally open contact depending on the arrangement of the permanent magnet,
When the temperature-sensitive ferrite reaches the Curie temperature and changes to a non-magnetic material due to heat generated by the heater, the reed switch switches to a closed contact or an open contact, thereby opening the contactor to the electronic tripping section. In addition to outputting an operation signal to set the state,
The heater is a coil-shaped heater arranged around the outer periphery of the temperature-sensitive operating mechanism component,
The temperature-sensitive operating mechanism component is configured such that the temperature-sensitive ferrite changes into a non-magnetic material due to heat generation in the coil-shaped heater due to an overload current in the current path, and the reed switch switches to an open contact or a closed contact. , outputting an operation signal as a long-time operation to open the contactor to the electronic tripping section, and generating an induced magnetic field in the coil-shaped heater due to a short-circuit current in the current path or an instantaneous operation current; acts on the inside of the temperature-sensitive operating mechanism component to create a magnetic saturation state, and the reed switch switches to an open contact or a closed contact, causing the electronic tripping section to perform an instantaneous action to open the contactor. An overcurrent switch that outputs an operation signal as an overcurrent switch. The temperature-sensitive operation mechanism component can achieve the long duration by adjusting the heat capacity of the component containing the temperature-sensitive ferrite and the heat conduction time for the temperature-sensitive ferrite to reach the Curie temperature by the coil-shaped heater. 2. The overcurrent switch according to claim 1 , wherein the time for the time-limited operation can be adjusted. An electronic circuit breaker comprising the overcurrent switch according to claim 1 or 2 , and a current transformer connected to the current path as a current detection means.

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