JP6924502B2 - Terminal connection failure detector - Google Patents

Description

The present invention detects abnormal overheating of the terminal to which the circuit breaker and the electric wire are connected to prevent the circuit breaker from burning and spreading the fire to the building materials and peripheral devices around the circuit breaker. The present invention relates to a terminal connection defect detecting device for detecting a defect.

As is well known, a circuit breaker is provided between an electric circuit, and when an accident current such as an overcurrent, a short-circuit current, or an electric leakage current in the electric circuit is detected and a predetermined operating condition is met, the electric circuit is electrically connected. It shuts off and operates to cut off the power supply to the load side.

The circuit breaker is provided with a connection terminal that enables repeated electrical connection with an external circuit. For circuit breakers that are installed in distribution boards such as residential distribution boards and control boards and are connected to the power lines of external circuits that are drawn into the boards, the power lines and circuits are installed at the construction site where the distribution boards are installed. The terminal on the power supply side of the circuit breaker is connected. At this time, if the connection between the power supply line and the connection terminal on the power supply side of the circuit breaker is inadequate, abnormal overheating may occur at the terminal portion.

In addition, there is a possibility that the terminals may become loose due to repeated ambient vibrations and temperature changes during many years of use. Abnormal overheating may occur at the terminal part, such as when the opportunity for regular maintenance and inspection is not properly obtained, or when the tightening confirmation of the terminal is not sufficient.

The cause of abnormal overheating of the terminal to which the electric wire is connected in the circuit breaker is the contact resistance between the electric wire and the terminal, such as insufficient tightening of the terminal screw or loosening of the terminal screw due to long-term use. There is an increase. As the electrical resistance of the connection part increases, a large amount of Joule heat is generated, and it is expected that the terminal part will generate heat.

In addition, heat generation can be expected due to an increase in contact resistance due to oxidation of the contact surface between the power supply line and the connection terminal of the circuit breaker, creep of the electric wire, interposition of foreign matter, and the like.

In addition, the cause of abnormal overheating other than the connection part between the power supply line and the connection terminal part is the internal resistance due to wear and tear of the contacts in the circuit breaker due to long-term use, oxidation and the intervention of foreign matter. Heat generation due to the increase can be expected.

If such an abnormally overheated state continues, the parts that make up the circuit breaker will burn out, and the circuit breaker itself will burn out, making it impossible to perform the original power-on / shut-off function. There is a concern that fire may spread to peripheral devices.

However, ordinary circuit breakers do not have a function to detect these abnormal overheating, and in order to prevent abnormal overheating, measures are taken to check the connection during construction and perform regular maintenance and inspection. Was there. Although these preventive measures are effective in preventing abnormal overheating, there is a risk that it will be difficult to notice abnormal overheating until the next maintenance and inspection in terms of suppressing abnormal overheating that has occurred over time. The concern that a burning accident or a fire spreading accident would occur due to such use could not be completely eliminated.

Therefore, a circuit with an overheat prevention device having a function of detecting these abnormal overheatings and, when the abnormal overheating occurs, shuts off the power supply to the load side to prevent a burning accident due to the abnormal overheating. The circuit breaker is disclosed. (Patent Document 1, Patent Document 2)
Patent Document 1 discloses the following as a means for detecting abnormal overheating. Bimetal plates 25 and 26 for overheat detection are fixed to the power supply side terminal and load side terminal of the circuit breaker, respectively, and a transmission plate that displaces according to the displacement of the bimetal plate is suspended between these two bimetal plates. And, although it is always locked to the transmission plate, when it is overheated, the displacement of the transmission plate releases the locking relationship with the transmission plate, so that the actuating rod moves to trip the circuit breaker. To prepare. Further, when the locking relationship between the transmission plate and the operating rod is released and the operating rod operates, the operating rod protrudes to the outside of the circuit breaker to display the operation and press the operating rod. An overheat prevention device that enables the circuit breaker to be reset by the above is added to a general circuit breaker.

In Patent Document 2, in view of the mechanical structure in Patent Document 1 described above, abnormal overheating is electrically detected, and the abnormal overheating is blocked by an electric signal output due to the detection. Disclosed is what drives a trip device that opens the contacts of the vessel.

Specifically, the mechanical operation disclosed in Patent Document 1 is made in view of the fact that it cannot be applied in many cases without changing the internal mechanism of the circuit breaker, and in particular, prevention of overheating of the circuit breaker alone. In addition to this, the problem was that the circuit breakers in the power supply system could be centrally managed and could be used for overheat protection of other devices such as electromagnetic switches installed in the same circuit.

As a configuration for detecting abnormal overheating, a temperature-sensitive element whose electrical output changes according to the temperature of the electric wire connection terminal and an abnormal overheating are detected by comparing the electrical output of the temperature-sensitive element with a normal level. It is equipped with a judgment circuit.

Examples of the temperature-sensitive element include a thermistor, a thermocouple using thermoelectromotive force, an infrared sensor for detecting radiated heat, and the like. The temperature-sensitive element is arranged near the terminal of the mold case. A form of embedding and arranging, a temperature sensor unit is configured by holding it on a resin-molded insulating support independently of the mold case and integrated, and the temperature sensor unit is used by using a groove for mounting an interpolar barrier. A form attached to the mold case, a form in which the temperature sensor unit is formed in a plate shape so that it can be attached by sandwiching it between the back surface and the board surface of the mold case, and a terminal used to insulate the circuit breaker terminal part of the heat sensitive element. A temperature-sensitive element is embedded in an insulator such as ceramic with high thermal conductivity, which is attached to the cover, and inserted into a hole provided in the insulating support of the temperature sensor unit so that it can be moved in the length direction by a spring. A form in which the tip of the insulator is brought into contact with the circuit breaker terminal portion while holding it elastically is disclosed.

Jikkensho 56-25156 Gazette Japanese Unexamined Patent Publication No. 62-8419

As disclosed in Patent Document 1 and Patent Document 2, it is possible to add a function of detecting abnormal overheating to a normal circuit breaker. However, in Patent Document 1, in order to add the function of detecting abnormal overheating, it is necessary to separately provide a space for arranging a mechanical mechanism for detecting abnormal overheating on the entire back surface side of the circuit breaker. In addition, the outer shape of the circuit breaker is significantly changed, and the circuit breaker is significantly modified.

Further, in Patent Document 2, when arranging an electric device, it is necessary to separately provide a unit provided with a temperature sensor such as a temperature sensitive element and a determination circuit, and attach the unit to a circuit breaker. Since there are many parts and it is necessary to introduce it as a temperature measurement system, it is complicated to add functions. Further, since the temperature sensitive element is attached after being electrically insulated from the main circuit, there is a problem that the temperature is indirectly sensed and it is difficult to grasp the accurate temperature rise.

Moreover, in any case, it acts as a single function for detecting abnormal overheating. Considering the recent trend of circuit breakers, it is necessary to maintain or improve the electrical safety performance while saving the space of the circuit breaker, that is, to maintain or improve the current breaking performance while reducing the external size of the circuit breaker. Although improvement is required, there is a problem that it is not realistic to configure a circuit breaker by adding a function for detecting abnormal overheating related to electrical safety in addition to these.

Therefore, the present invention has been made in view of the above problems, and can be retrofitted to a normal circuit breaker, and the mounting position is affected by the position of the circuit breaker main body, the electric wire connected to the circuit breaker, and the like. It is an object of the present invention to provide a connection failure detection device which can be mounted without removing the circuit breaker from the mounting plate at the time of mounting.

The connection failure detection device according to the present invention is configured to solve the above-mentioned problems, and is connected to the power supply terminal of the circuit breaker so as to be thermally conductive and electrically conductive, and from the power supply terminal. A thermal element that receives the heat conduction of the above and is displaced according to the heat generation state of the power supply terminal, a display unit that receives the displacement of the thermal element and displays the heat generation state, and these connection portions, the thermal element, and a display. It is equipped with a housing for accommodating the part, and can be freely attached to and detached from the outside of the circuit breaker to the power supply terminal. It provides a connection failure detection device for the terminals.

According to this configuration, the connection part is connected to the power supply terminal of the circuit breaker from the outside of the circuit breaker, and the circuit breaker can be freely attached to and detached from the power supply terminal without removing the circuit breaker from the mounting plate. A connection failure detection device can be attached, and the magnitude of the force required to display the state of heat generation is set to a displacement force of the thermal element, that is, a force smaller than the driving force of the bimetal. The unit can hold the display when the temperature of the power supply terminal is the highest value.

Further, the mounting position of the connection defect detection device may be configured to be located between the mounting surface of the circuit breaker and the electric wire connected to the power supply terminal.

According to such a configuration, an empty space in a normal circuit breaker can be used, and it is not easily affected by the position of an electric wire or the like connected to the circuit breaker.

As described above, according to the present invention, it can be retrofitted to a normal circuit breaker, and the mounting position is not affected by the position of the circuit breaker main body or the electric wire connected to the circuit breaker. It is possible to provide a connection failure detection device that can be mounted without removing the circuit breaker from the mounting plate for mounting.

A schematic configuration diagram of a state in which a connection failure detection device showing the first embodiment of the present invention is attached to a circuit breaker is shown. The schematic diagram of the main part in the state where the above connection failure detection device is attached to the circuit breaker is shown. A schematic configuration diagram of the above connection failure detection device is shown. The structure for detecting the connection failure of the terminal in the conventional example is shown.

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

(First Embodiment)
FIG. 1 shows a schematic configuration diagram of a state in which the connection failure detection device 2 according to the present embodiment is attached to the circuit breaker 1. FIG. 2 shows a schematic view of a main part in a state where the connection failure detection device is attached to the circuit breaker. FIG. 3 shows a schematic configuration diagram of the connection failure detection device.

First, the basic structure of the circuit breaker 1 will be described. The circuit breaker 1 is configured such that the outer shell is covered with a body made of a mold case. The body consists of a base on which the components of the circuit breaker are mounted and fixed, and a cover that covers the base and covers the main components. A plurality of power supply terminals 111 connected to an external conductor are provided corresponding to the power supply of each pole, and each is exposed to the outside.

An insulating wall 11 for insulating each power supply terminal is provided between the power supply terminals 111.

Inside the body, a fixed contact 110 and a movable contact 112 that turn on and off the electric circuit on the power supply side and the electric circuit on the load side are arranged.

Further, the opening / closing mechanism portion that drives the opening / closing of the fixed contact 110 and the movable contact 112, and the opening / closing mechanism portion that acts on the opening / closing mechanism portion by detecting an abnormal current flowing in the electric circuit to perform the pulling operation of the opening / closing mechanism portion. A trip device unit for opening and driving the fixed contact 110 and the movable contact 120 is provided.

One end of the fixed contact 110 is provided with a power supply terminal 111 connected to a conductor on the power supply side, and the other end is provided with a fixed contact.

A movable contact 112 having a movable contact facing the fixed contact is arranged opposite to the fixed contact 110, and is held by an opening / closing mechanism and driven to open / close with respect to the fixed contact 110.

An electric wire 3 is connected to the power supply terminal 111 from the outside. A crimp terminal 31 is attached to the tip of the electric wire 3 by caulking, and the crimp terminal 31 is screwed and fixed to the power supply terminal 111 by a terminal screw 1103.

(Connection failure detection device 2)
Next, the configuration of the connection failure detection device 2 that realizes the function of detecting the connection failure of the electric wire 3 at the power supply terminal 111 will be described.

The connection failure detection device 2 receives heat conduction from the power supply terminal 111 and the connection portion 21 which is electrically and electrically conductively connected to the power supply terminal 111, and is displaced according to the heat generation state of the power supply terminal. The thermal element 22 is provided with a display unit 23 that receives the displacement of the thermal element 22 and displays a state of heat generation, and a housing 24 that houses the connection unit 21, the thermal element 22, and the display unit 23. It is composed.

The connection portion 21 has a through hole through which the terminal screw 1103 of the circuit breaker 1 is passed so that it may be sandwiched between the crimp terminal 31 of the electric wire 3 and the power supply terminal 111 when it is attached to the power supply terminal 111. Then, it is tightened and fixed by the terminal screw 1103. By being fixed in this way, heat is conducted directly to the connection. Further, since it is fixed while maintaining electrical conductivity, it is possible to prevent an increase in contact resistance.

The thermal element 22 is configured by using a bimetal that is displaced by receiving heat conduction from a connecting portion 21 connected to the power supply terminal 111. Specifically, the thermal element 22 is fixed to the connecting portion 21 by welding.

The display unit 23 is arranged in the vicinity of the thermal element 22, and receives the displacement of the thermal element 22 to drive the contact. Specifically, the thermal element 22 has a rotation axis in a direction orthogonal to the displacement direction and is held rotatably. The display unit 23 is provided with a contact portion with the thermal element 22 and a visual recognition portion that can be visually recognized from the outside.

The connection unit 21, the thermal element 22, and the display unit 23 are housed in a housing 24 and integrally configured. The width of the housing 24 is formed to be the size of one pole of each pole of the circuit breaker 1, and the housing 24 can be mounted on a predetermined pole. Specifically, when all three poles are attached, the housings 24 are formed so as not to come into contact with each other. Further, the height direction is formed so as to fit between the mounting surface of the circuit breaker 1 and the electric wire 3 connected to the power supply terminal 111.

The housing 24 is provided with a confirmation window at a location corresponding to the viewing unit so that the viewing unit on the display unit 23 can be visually recognized from the outside of the housing 24.

Although the temperature of the power supply terminal 111 varies depending on the magnitude of the current used, the state when the temperature of the power supply terminal 111 is the highest value can be maintained. A force required to rotate the display unit 23 is provided by a predetermined magnitude, and the rotationally advanced displacement can be maintained. Specifically, the predetermined magnitude is set to a force smaller than the displacement force (bimetal driving force) of the thermal element 22, and even when the displacement of the thermal element 22 returns, the display unit 23 The rotation can hold the maximum value.

(Mounting position of connection failure detection device 2)
The connection failure detection device 2 is located between the mounting surface of the circuit breaker 1 and the electric wire 3 connected to the power supply terminal 111 at the time of mounting.

Specifically, the connection defect detection device 2 is attached by tightening and fixing the connection portion 21 with the terminal screw 1103 so that the connection portion 21 is sandwiched between the crimp terminal 31 of the electric wire 3 and the power supply terminal 111.

By being fixed in this way, the housing 24 is located between the mounting surface of the circuit breaker 1 and the electric wire 3, fits in the dead space, and is connected to the circuit breaker main body and the circuit breaker. It is not easily affected by the position such as.

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

For example, the housing 24 of the connection failure detection device 2 is provided in a size of one pole for each pole, but has a size equivalent to that of three poles, which is common in a circuit breaker used as a main switch. The connecting portion 21, the thermal element 22, and the display portion 23 may also be formed and housed in the housing together with the three poles.

With this configuration, it is possible to save the trouble of installing the connection failure detection device 2 for each pole.

Further, although the display unit 23 is driven by a rotary type provided with a rotating shaft, it may be configured as a linear movement type in which the display unit is pushed in a certain direction as the thermal element 22 is displaced.

1 Circuit breaker 11 Insulation wall 110 Fixed contact 1103 Terminal screw 111 Power terminal 112 Movable contact 2 Connection failure detection device 21 Connection 22 Thermal element 23 Display 24 Housing 3 Electric wire 31 Crimping terminal

Claims (2)

A connection that is heat-conducting and electrically conductively connected to the power terminal of the circuit breaker,
A thermal element that receives heat conduction from the power supply terminal and displaces according to the heat generation state of the power supply terminal.
A display unit that displays the state of heat generation in response to the displacement of the thermal element, and
A housing for accommodating these connection parts, thermal elements, and display parts is provided.
It is a terminal connection failure detection device that can be freely attached to and detached from the outside of the circuit breaker to the power supply terminal.
The display unit is a terminal connection failure detecting device characterized in that it can hold a display when the temperature of the power supply terminal is the highest value.
The mounting position of the connection failure detection device is
The connection failure detecting device according to claim 1, wherein the device is located between a mounting surface of a circuit breaker and an electric wire connected to a power supply terminal.

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