JP2020115481A - Terminal overheat detection device - Google Patents

Abstract

To provide a terminal overheat detection device capable of detecting abnormal overheat of a terminal by simple configuration, without modifying a circuit breaker, and capable of confirming whether or not normal output can be obtained by test operation.SOLUTION: A terminal overheat detection device is a terminal temperature display device attached to the terminal 12 of an electrical machine by means of a terminal screw 11 for fixing a wire 3, and includes a connection connected with the terminal and to which heat of the terminal is conducted, a thermal element having one end fastened to the connection and the other end disposed displaceably in response to change in the heat, a displacement transmission part to which displacement of the thermal element is transmitted and which displaces reciprocally in response to reaction, and a signal output part which is driven when the displacement of the displacement transmission part is transmitted, and exceeds a prescribed threshold level.SELECTED DRAWING: Figure 1

Description

The present invention detects the temperature of a terminal portion of a circuit breaker to prevent burnout of connected electric wires and circuit breakers and spread of fire to construction materials and peripheral equipment around the circuit breakers. The present invention relates to a terminal overheat detection device.

The circuit breaker detects a fault current such as an overcurrent, a short-circuit current or a leakage current in the electric circuit, and when a predetermined operating condition is met, the circuit breaker cuts off the power supply to the load side.

The circuit breaker is provided with a terminal at each terminal for electrical connection with an electric wire or a load device. Circuit breakers built into switchboards such as distribution boards and control boards for homes have electric wires drawn in at the construction site, and the wires are caulked with crimp terminals. It is connected to the terminal with screws. At this time, if the crimp terminal and the terminal of the circuit breaker are not tightly screwed together, abnormal overheating may occur in the terminal during use of the circuit breaker.

Also, even after many years of use, the terminal screws attached to the terminals may loosen due to repeated expansion and contraction due to ambient vibration and temperature changes. Unless the screws are retightened, loosening of the screws may cause abnormal overheating.

Abnormal overheating of terminals occurs due to a large amount of Joule heat generated due to an increase in the contact resistance between the crimp terminal to which the wire is attached and the terminal due to loosening of the terminal screw.

In addition, abnormal overheating also occurs due to an increase in contact resistance due to oxidation of the contact surface between the crimp terminal of the electric wire and the terminal of the circuit breaker and an increase in contact resistance due to entrapment of foreign matter.

If such a state of abnormal overheating continues, the components constituting the circuit breaker and the connected electric wires may be ignited, and there is a concern that the construction material around the circuit breaker and the peripheral equipment may spread.

However, a normal circuit breaker does not have a function of detecting abnormal overheat of these terminals. In general, to prevent abnormal overheating of terminals, measures are taken to check connections during construction and perform regular maintenance inspections (such as tightening terminal screws). Although these preventive measures are effective in preventing abnormal overheating, they cannot be noticed until the next maintenance inspection, so it is not possible to completely prevent burnout accidents and fire spread accidents due to long-term use. Can not.

Therefore, a circuit breaker with an overheat prevention device equipped with a function that detects abnormal overheat of terminals and cuts off the power supply to the load side when abnormal overheat occurs to prevent burnout accidents due to abnormal overheat Vessels are disclosed. (Patent Document 1, Patent Document 2)

Patent Document 1 discloses the following as a device for detecting abnormal overheating. Bimetal plates 25 and 26 for detecting overheat are fixed to the power supply side terminal and the load side terminal of the circuit breaker, respectively, and a transmission plate which is displaced following the displacement of the bimetal plate is suspended between the two bimetal plates. And, the operating rod that is normally locked to the transmission plate is moved by tripping the circuit breaker by releasing the locking relationship with the transmission plate due to displacement of the transmission plate when overheated. Be prepared. Further, when the locking relationship between the transmission plate and the operating rod is released and the operating rod is operated, the operating rod is projected to the outside of the circuit breaker to indicate the operation and the operating rod is pressed. An overheat prevention device that enables resetting of the circuit breaker is provided in addition to a general circuit breaker.

Patent Document 2 is made in view of the mechanical structure in the above-mentioned Patent Document 1, and electrically detects abnormal overheat, and shuts off by an electric signal output when the abnormal overheat is detected. It is disclosed to drive a tripping device which opens the contacts of the vessel.

Specifically, the mechanical operation disclosed in Patent Document 1 has been made in view of the fact that it cannot be applied unless the internal mechanism of the circuit breaker is changed. In addition to this, it is an object to be able to centrally manage the circuit breaker in the power supply system and to be used for overheat protection of other devices such as an electromagnetic switch installed in the same circuit.

As a configuration for detecting abnormal overheat, a temperature sensitive element whose electrical output changes according to the temperature of the wire connection terminal and an abnormal overheat are detected by comparing the electrical output of the temperature sensitive element with a normal level. And a determination circuit.

Examples of the temperature sensitive element include a thermistor, a thermocouple using thermoelectromotive force, and an infrared sensor for detecting radiant heat.As the arrangement of the temperature sensitive element, the temperature sensitive element is placed near the terminals of the mold case. Formed by embedding and arranging, a temperature sensor unit is formed integrally by being held by a resin-molded insulating support independent of the mold case, and the temperature sensor unit is formed by using the mounting groove of the inter-electrode barrier. Attached to the mold case, the temperature sensor unit is formed in a plate shape so that it can be mounted by sandwiching it between the back surface of the mold case and the board surface, and a terminal used for insulating the circuit breaker terminal Attached to the cover, the temperature sensitive element is embedded in an insulator such as ceramic with high thermal conductivity and inserted into the hole provided in the insulating support of the temperature sensor unit so that it can be moved in the length direction by a spring. There is disclosed a mode in which the tip end of the insulator is held elastically and the tip of the insulator is brought into contact with the breaker terminal portion.

Japanese Utility Model Publication No. 56-25156 JP 62-8419 A

As disclosed in Patent Document 1 and Patent Document 2, it is possible to add a function of detecting abnormal overheat of a terminal to a normal circuit breaker. However, in Patent Document 1, when adding a function for detecting abnormal overheat, it is necessary to separately provide a space for disposing a mechanical mechanism for detecting abnormal overheat on the entire back surface side of the circuit breaker. Since the circuit breaker is greatly modified, such as the outer shape of the circuit breaker being greatly changed, there is a problem that the number of steps and the cost are increased.

Further, in Patent Document 2, when disposing an electric device, it is necessary to separately provide a unit including a temperature sensor such as a temperature sensitive element and a determination circuit and attach the unit to a circuit breaker. There are many additional parts, and since it is necessary to introduce it as a temperature measurement system, it is complicated to add functions. In addition, since an electric element such as a temperature sensitive element is used, there is a problem that it is difficult to understand at a glance whether or not a failure has occurred during long-term use.

Therefore, the present invention has been made in view of the above problems, and it is possible to detect abnormal overheating of terminals with a simple configuration without the need to modify the circuit breaker, and whether normal output can be obtained by a test operation. It is an object of the present invention to provide a terminal overheat detecting device capable of confirming whether or not it is.

A terminal overheat detection device according to the present invention is configured to solve the above-mentioned problems, and is a terminal overheat detection device that is attached to a terminal of an electric device by a terminal screw that fixes an electric wire to detect the temperature of the terminal. A connection part connected to the terminal for conducting heat from the terminal, and a heat fixed to the connection part at one end and displaceably arranged at the other end in response to the change in heat. Moving element, a displacement transmitting section for transmitting the displacement of the thermal element and reciprocating displacement in response to the response, and a signal driven when the displacement of the displacement transmitting section is transmitted and exceeds a predetermined threshold value. A terminal overheat detecting device is configured by including an output section.

According to this configuration, the displacement of the displacement transmission unit is transmitted by conducting the heat of the terminal overheat detection device to the terminal of the circuit breaker, and the signal output unit is driven when the displacement exceeds a predetermined threshold value. Because of the configuration, it is possible to provide a terminal overheat detection device that can detect abnormal overheating of terminals with a simple configuration without the need to modify the circuit breaker.

Further, since the connecting portions on which the thermal elements are disposed are disposed corresponding to the number of terminals of the circuit breaker, the displacement transmitting portions are commonly provided on the respective thermal elements. The maximum displacement in each of the thermal elements may be transmitted to the displacement transmitting section to drive the signal output section.

According to such a configuration, it is possible to drive the signal output unit by catching the heat generation of the terminal that generates the most heat from the plurality of terminals of the circuit breaker, and therefore it is not necessary to arrange the switch means for each terminal. Therefore, a plurality of terminals can be collectively monitored with a small number of parts.

In addition, a part of the connecting portion is exposed to the outside, and includes a thermoelectric element, a displacement transmitting portion, and a substantially rectangular parallelepiped housing that houses the signal output portion,

It may be configured to include a test operation unit that drives the signal output unit by displacing the displacement transmission unit by operating from the outside of the housing.

With this configuration, the driving of the signal output unit can be confirmed by the test operation unit, and thus it is possible to test whether the signal output unit can normally output the signal.

As described above, according to the present invention, it is possible to confirm whether abnormal overheat of a terminal can be detected with a simple configuration without modifying the circuit breaker and a normal output can be obtained by a test operation. It is possible to provide a terminal overheat detection device that can be performed.

The schematic diagram of the state which attached the terminal overheat detection apparatus which shows embodiment of this invention to the circuit breaker is shown. The schematic diagram of the attachment method of the said terminal overheat detection apparatus is shown. The above-mentioned terminal overheat detection device is shown. The internal assembly drawing of the said terminal overheat detection apparatus is shown. Sectional drawing AA (assembly structure of a switch means) shown in FIG. 4 is shown. The external appearance of the test operation means of the above-mentioned terminal overheat detection device is shown. FIG. 7 is a sectional view BB shown in FIG. 6 (assembly structure of test operation means). The structure which detects the connection failure of the terminal in a prior art example is shown.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration diagram in a state where the terminal overheat detection device 2 according to the present embodiment is attached to the circuit breaker 1. FIG. 2 shows a schematic diagram of a method of mounting the terminal overheat detection device. FIG. 3 shows a terminal overheat detection device. FIG. 4 shows an internal assembly diagram of the terminal overheat detection device. FIG. 5 shows the assembly structure of the switch means of the terminal overheat detection device. FIG. 6 shows the test operation means of the terminal overheat detection device. FIG. 7 shows the assembly structure of the test operating means. FIG. 8 shows a structure for detecting a terminal connection failure in the conventional example.

First, the basic structure of the circuit breaker 1 shown in FIGS. 1 and 2 will be described. 1 and 2, the circuit breaker 1 is configured by a circuit breaker housing having an outer shell made of a molded case. The circuit breaker housing is composed of a base 101 for mounting internal parts of the circuit breaker, and a cover 102 that covers the internal parts by covering the base. Inside the circuit breaker 1, a fixed contactor (not shown) integrated with the terminal 12 and a movable contactor (not shown) for connecting and disconnecting the electric path on the power supply side and the electric path on the load side. Is provided. Further, an opening/closing mechanism section (not shown) for driving the fixed contactor and the movable contactor to open and close, and an abnormal current flowing in the electric path are detected to act on the opening/closing mechanism section to trip the opening/closing mechanism section. And a tripping device section (not shown) for driving the fixed contactor and the movable contactor to open.

The circuit breaker 1 is provided with a plurality of terminals 12 connected to external conductors corresponding to the power sources of the respective poles, and each is exposed to the outside.

The electric wire 3 is connected to the terminal 12 from the outside. A crimp terminal 31 is attached by caulking to the tip of the electric wire 3, and the crimp terminal 31 is screwed and fixed to the terminal 12 by a terminal screw 11.

Next, the terminal overheat detection device 2 attached to the circuit breaker 1 will be described with reference to FIGS. 1 and 2. The heat conduction terminal 21, which is a connection portion of the terminal overheat detection device 2 that is connected to the terminal 12 and conducts heat of the terminal 12, has a through hole that allows the terminal screw 11 of the circuit breaker 1 to pass therethrough, The heat conducting terminal 21 is clamped and fixed by the terminal screw 11 so as to be sandwiched between the crimp terminal 31 and the terminal 12 of the electric wire 3. The terminal overheat detection device 2 is located at the time of mounting between the mounting surface of the circuit breaker 1, that is, the bottom surface of the circuit breaker 1 and the electric wire 3 connected to the terminal 12.

Next, the configuration of the terminal overheat detection device 2 having a function of detecting abnormal overheat of the terminal 12 will be described with reference to FIGS. 3, 4, and 5.

As shown in FIGS. 3, 4 and 5, the terminal overheat detecting device 2 is connected to the terminals 12 of the respective poles of the circuit breaker 1 and a heat conduction terminal 21 which is a connection portion through which heat of the terminals 12 is conducted. A first heat transfer element 22 fixed to the heat transfer terminal 21 and a displacement transfer section which is disposed in the vicinity of the heat transfer element 22 and which transfers the displacement of the heat transfer element 22 and reciprocally moves in response to the reaction. Of the second actuating body 23, which is a displacement transmitting section that is disposed in the vicinity of the first actuating body 23 and that reciprocally displaces in response to the reciprocating displacement of the first actuating body 23. A micro switch 25 that is a signal output unit that is driven when the displacement of the part is transmitted and exceeds a predetermined threshold value, and these thermal elements 22, the first actuation body 23, the second actuation body 24, and the micro switch. A housing 26 for housing 25 is provided.

The thermodynamic element 22 fixed to the heat conduction terminal 21 is configured by using a bimetal that receives heat conduction from the heat conduction terminal 21 connected to the terminal 12 and is displaced quantitatively. In FIG. 4 and FIG. 5, the thermal element 22 is fixed to the heat conduction terminal 21 by screw tightening, but it is not limited to screw tightening and may be fixed by welding or rivet.

The first actuation body 23 is biased by an elastic member (not shown) that biases the first actuation body 23 so as to come into contact with the position restricting portion 261 of the housing 26, and a constant gap with the thermal element 22. Are arranged in the state of being provided.

As shown in FIG. 5, the second actuation body 24 is biased by the elastic member 241 so as to come into contact with the micro switch 25. The second actuation body 24 is a first actuation body that rotates in the direction A shown in FIG. 5 in response to the displacement of the thermal motion element 22 when the thermal motion element 22 is displaced by heat conduction from the thermal conduction terminal 21. Interlocking with 23, it rotates in the B direction shown in FIG. 5 against the elastic member 241. When the terminal 12 is abnormally overheated, that is, when the displacement of the thermal element 22 exceeds a certain amount, the contact operating portion of the micro switch 25 is operated by the second actuating body 24, and the micro switch 25 is operated. Is operated to output a signal indicating abnormal overheating of the terminal 12.

When the heat generation of the terminal 12 is stopped, the displacement of the thermal element 22 becomes smaller. As the displacement of the thermal element 22 becomes smaller, the first actuation body 23 and the second actuation body 24 become elastic members (not shown) that bias the first actuation body 23 or the second actuation body 24. The elastic member 241 that urges the terminal 12 rotates to a position before the terminal 12 generates heat. When the abnormal overheating of the terminal 12 is subsided, that is, when the displacement of the thermal element 22 is less than or equal to a certain amount, the contact operation portion of the micro switch 25 is operated by the second actuation body 24. The micro switch 25 is operated so as not to output a signal indicating abnormal overheating of the terminal 12.

The heat generated by the terminal 12 is conducted through the heat conducting terminal 21. Since the thermal element 22 is quantitatively displaced according to the amount of heat, the first operating body 23 and the second operating body 24 rotate according to the amount of displacement of the thermal element 22. Therefore, the amount of heat generated from the terminal 12, the amount of displacement of the thermal element 22, and the amounts of rotation of the first actuating body 23 and the second actuating body 24 are correlated, so that when the terminal 12 abnormally overheats, That is, when the displacement of the thermal element 22 exceeds a certain amount and when the terminal 12 is not abnormally overheated, that is, when the amount of displacement of the thermal element 22 is less than a certain amount, the micro The state of the contact operation unit of the switch 25 can be switched.

With such a configuration, the heat conduction terminal 21 of the terminal overheat detecting device 2 is attached to the terminal 12 of the existing circuit breaker with the terminal screw 11, so that there is no need to modify the circuit breaker 1 and the terminal overheat detecting device is not required. 2 can be attached. In addition, the contact operation portion of the microswitch 25 is operated when the displacement of the thermal element 22 fixed to the heat conduction terminal 21 exceeds a certain amount, so that the terminal has a simple configuration. It is possible to output 12 abnormal overheat states.

Although the micro switch 25 is configured to be operated via the first actuating body 23 and the second actuating body 24 in FIGS. 4, 5 and 6, the present invention is not limited to this and, for example, a thermal element. The micro switch 25 may be operated by directly contacting the contact operation part of the micro switch 25 with 22.

Further, in the present embodiment, the operation of the contact operation part of the micro switch 25 is changed from the state of contacting the contact operation part to the state of non-contact when the thermal element 22 is displaced. It goes without saying that the moving element 22 may be brought into a contact state when the moving element 22 is displaced.

Next, a terminal overheat detecting device 2 capable of collectively monitoring a plurality of terminals 12 and detecting abnormal overheating by the terminal 12 which is most generating heat will be described with reference to FIGS. 4 and 5.
The first actuation body 23 shown in FIG. 4 is rotatably fixed to the housing 26 so as to extend across the terminals 12 of the respective poles.

With such a configuration, of the thermal elements 22 fixed to the terminal 12 of the pole across which the first operating element 23 extends, only the thermal element 22 displaced at the highest temperature has the first operating element. 23 interlock with each other and rotate in the direction A shown in FIG. 5 against an elastic member (not shown) that biases the first actuation body 23, and the first actuation body 23 causes the second actuation body 24 to move. By rotating in the direction of B shown in FIG. 5 against the elastic member 241, the contact operation portion of the microswitch 25 can be operated. Therefore, it is possible to collectively monitor the heat generation state of the plurality of terminals 12 over which the first actuating body 23 extends, and it is possible to detect abnormal overheating based on the terminal 12 that generates the most heat. As a result, the abnormal overheat of each terminal 12 can be detected with a smaller number of components than that in which the terminal overheat detection device 2 is arranged on each terminal 12.

4 and 5, the micro switch 25 is configured to be operated via the first actuation body 23 and the second actuation body 24, but is not limited to this, and for example, the first actuation body may be used. The micro switch 25 may be operated by directly contacting the operation portion 251 of the micro switch 25 with 23.

Next, the terminal overheat detecting device 2 capable of testing that the microswitch 25 can normally output a signal by intentionally operating the microswitch 25, which is the switch means, by the test operation means, will be described with reference to FIGS. A description will be given with reference to FIG.

As shown in FIG. 6, in the case 26 in which the micro switch 25 is arranged, the test operation means 27 is inserted on the surface near the micro switch 25.

As shown in FIG. 7, one end side of the test operating means 27 is exposed to the outside of the housing 26, and the other end side of the test operating means 27 is inside the housing 26 so that the operating means of the micro switch 25 can be operated. It is inserted together with the test elastic member 271. In the case of the present embodiment, the other end side of the test operation means 27 is arranged so as to rotate the second actuation body 24.

When one end side of the test operation means 27 exposed to the outside of the housing 26 is operated, the other end side of the test operation means 27 causes the operation portion of the microswitch 25 to operate and the displacement of the thermal element 22 to be constant. Operate in the same way as when the amount is exceeded. For example, in the case of FIGS. 5, 6 and 7, when one end side of the test operation means 27 is pushed, the test operation means 27 moves toward the inside of the housing 26 against the elastic member 271 for test, The other end side of the test operation means 27 is configured to rotate the second actuation body 24 in the B direction shown in FIG.

With such a configuration, by operating the test operation means 27, the operation portion of the microswitch 25 can be operated intentionally. As a result, it is possible to confirm that the micro switch 25 operates normally by the presence or absence of the signal output of the micro switch 25 when the test operation means 27 is operated, so that the test operation of the micro switch 25 can be easily confirmed. The detection device 2 can be provided.

In addition, in FIG. 5, FIG. 6 and FIG. 7, the second operating body 24 is rotated by pushing the test operating means 27, but the present invention is not limited to this. It goes without saying that the configuration may be such that the operating portion of the microswitch 25 is operated by operating it. For example, the test operating means is not limited to the push button type, but may be a slide button type, and the test operating means 27 is not limited to the configuration of rotating the second actuation body 24, but the first actuation body 23 is turned. The configuration may be such that the operation portion of the micro switch 25 is directly operated.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Circuit breaker 11 Terminal screw 12 Terminal 2 Terminal overheat detection device 21 Heat conduction terminal 22 Thermal element 23 First actuation body 24 Second actuation body 241 Elastic member 25 Switch means (micro switch)
26 housing 261 position regulating section 27 test operating means 271 elastic member for test 3 electric wire 31 crimp terminal

Claims (3)

A terminal overheat detection device which is attached to a terminal of a circuit breaker by a terminal screw for fixing an electric wire and detects the temperature of the terminal,
A connection part connected to the terminal to conduct heat of the terminal,
A thermal element having one end fixed to the connecting portion and the other end displaceably arranged in response to the change in heat;
A displacement transmitting section that transmits the displacement of the thermal element and reciprocates in response to the response,
And a signal output unit that is driven when the displacement of the displacement transmitting unit is transmitted and exceeds a predetermined threshold value.
While the connection portion in which the thermal element is arranged is arranged corresponding to the number of the terminals of the circuit breaker,
Since the displacement transmitting section is provided in common to each of the thermal elements,
The maximum displacement in each of the thermal elements is transmitted to the displacement transmitting section,
The terminal overheat detection device according to claim 1, wherein the signal output unit is driven.
A part of the connecting portion is exposed to the outside, and the thermal element, the displacement transmitting portion, and a substantially rectangular parallelepiped housing for housing the signal output portion,
3. The terminal overheat detection device according to claim 1, further comprising a test operation unit that drives the signal output unit by displacing the displacement transmission unit by operating from the outside of the housing. ..

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