KR20170123091A - Molded Case Circuit Breaker with function of Protecting Overheat - Google Patents

Abstract

The present invention relates to a molded case circuit breaker with an overheat prevention function, and more particularly, to a molded case circuit breaker with an overheat prevention function capable of performing a stable operation and preventing the generation of an overheat inside the circuit breaker in a normal current conduction by including a temperature detection unit and a cooling device. The molded case circuit breaker with an overheat prevention function according to an embodiment of the present invention includes: a temperature detecting unit which detects an ambient temperature of the circuit breaker using a first temperature sensor installed in the outside of a case; a micro controller unit (MCU) which receives the ambient temperature measured by the temperature detecting unit and compares the measured ambient temperature with a predetermined external reference temperature to determine the ambient temperature; and a heat dissipating means installed in a part of the case and driven according to the control of the MCU.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a circuit breaker having an overheat prevention function,

The present invention relates to a circuit breaker having an overheat prevention function, and more particularly, to a circuit breaker having an overheat prevention function for preventing overheating inside a circuit breaker when normal current is supplied and performing stable operation, Circuit breaker.

In general, MCCB (Molded Case Circuit Breaker) is an electric device that is installed in a switchboard mainly in water distribution facilities such as factories and buildings, and automatically protects circuits and loads by automatically shutting off the circuit in the event of an overload condition or a short circuit. Delay trip operation is performed for the short-circuit current, and momentary trip operation is performed for the short-circuit current.

Such a circuit breaker has a structure in which an opening / closing device, a detection mechanism, and an SOHO device are combined in a case formed of an insulating material. FIG. 1 is a cross-sectional view of a conventional circuit breaker according to the prior art. A fixed contact 2 connected to a power source side terminal and a movable contact 3 connected to or disconnected from a fixed contact 2 are provided inside the case 1. The switch 5 is for operating the circuit in a closed or open state by connecting or disconnecting the movable contact 3 to or from the stationary contactor 2 and comprises a handle 6 for manual operation and a lever And the like to transmit a force to the shaft 7 to which the movable contact is coupled. The detection mechanism 8 includes a heater 8a that detects an overcurrent, a bimetal 8b that is connected to the heater 8a and curves when heat is transmitted thereto, and a crossbar (8d) and the like.

The circuit breaker is intended to quickly open the fault current to block the fault current, but it also has the function of allowing the load current to flow safely and normally. For this purpose, the cutoff time corresponding to the amount of current flowing on the circuit is determined by the KS standard standard.

When the overload current is higher than the rated current, the bimetal 8b curves due to the heat generation and trips. However, when the overheat current is higher than the rated current, the bimetal 8b is bent due to the heat generated by the overheat current, so that the bimetal 8b must be normally tripped. However, So that a trip operation may be performed. In the case of such a malfunction, the circuit is prevented from normally energizing.

FIG. 2 shows an example of a graph showing the change in operation time of the circuit breaker according to the ambient temperature. In general, the installation temperature of circuit breaker is based on 25 ℃. It is shown that the operation time decreases when the ambient temperature rises. That is, when the ambient temperature rises, there is a problem that the bimetal is affected by the ambient temperature to cause a malfunction or to perform the shutdown operation below the normal range even though the ambient temperature is not.

An object of the present invention is to provide a circuit breaker having a temperature detection unit and a cooling device and having an overheat prevention function for preventing overheating inside the circuit breaker and performing stable operation when a normal current is supplied, .

The circuit breaker having an overheat prevention function according to an embodiment of the present invention includes a temperature detector for detecting an ambient temperature of the circuit breaker using a first temperature sensor installed outside the case; An MCU (Micro Controller Unit) which receives the ambient temperature measured by the temperature detector and compares the measured ambient temperature with a preset external reference temperature; And a heat dissipating unit installed in a part of the case and operating under the control of the MCU.

Here, the power supply unit may further include a power unit connected to the three-phase circuit to convert AC into DC and supply power to the MCU and the heat dissipation unit.

The heat dissipating means may be a fan.

In addition, the case may be provided with a plurality of slits or holes formed in a portion where the heat dissipating means is installed.

The temperature detecting unit may further include a second temperature sensor installed inside the case to measure an internal temperature of the case.

The apparatus may further include a current detector connected to the three-phase circuit to detect a current flowing in each phase and transmit the detected current to the MCU.

In the MCU, the internal temperature measured by the second temperature sensor is compared with a preset internal reference temperature to operate the heat dissipating means.

In the MCU, the current value measured by the current detector is compared with a predetermined reference current, and the heat dissipating unit is operated.

According to the wiring breaker having the overheat prevention function according to the embodiment of the present invention, the temperature around the bimetal inside the breaker can be prevented from being overheated, thereby preventing the occurrence of interruption even during normal current application.

Further, there is an effect that the delay trip operation time due to the overcurrent can be normally maintained close to the reference temperature.

1 is a longitudinal sectional view of a wiring breaker according to the prior art.
2 is a graph showing a change in operation time of a circuit breaker according to ambient temperature in a trip device of a circuit breaker according to the prior art.
3 is a perspective view of a circuit breaker according to an embodiment of the present invention.
4 is a longitudinal sectional view of a circuit breaker according to an embodiment of the present invention.
5 is a circuit diagram showing the operation of a wiring breaker having an overheat prevention function according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, which are intended to illustrate the present invention in a manner that allows a person skilled in the art to easily carry out the invention. And does not mean that the technical idea and scope of the invention are limited.

3 and 4 are a perspective view and a longitudinal sectional view, respectively, of a circuit breaker according to an embodiment of the present invention. 5 is a circuit diagram showing the operation of a wiring breaker having an overheat prevention function according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wiring breaker having an overheat prevention function according to each embodiment of the present invention will be described in detail with reference to the drawings.

The circuit breaker having an overheat prevention function according to an embodiment of the present invention includes a temperature detector 30 for detecting the ambient temperature of the circuit breaker by a first temperature sensor 31 provided outside the case 10; An MCU (Micro Controller Unit) 35 for receiving the ambient temperature measured by the temperature detector 30 and comparing the measured ambient temperature with a preset external reference temperature; And a heat dissipating means (40) installed in a part of the case (10) and operating under the control of the MCU (35).

The circuit breaker for wiring comprises a stationary contactor 11 connected to a power source side in a case 10 and a movable contactor 12 which can receive or receive a rotational force from the stationary contactor 11, do. The arc contact portion 15 is provided around the contacts of the stationary contact 11 and the movable contact 12 so as to extinguish an arc generated when the stationary contact 11 and the movable contact 12 are closed.

A switchgear portion 16 is provided at the center of the case 10 for contacting or disconnecting the movable contactor 12 with the stationary contactor 11 to switch the circuit to a closed or open state. The switch 16 is provided with a handle 17 which is exposed to the upper portion of the case 10 and can be manually operated by the user, a trip spring 18 connected to the lower portion of the handle 17 to transmit a force, (Not shown) operated by the trip spring 18 and a shaft 19 rotated by the link. The movable contact 12 is coupled to the shaft 19 and rotated.

The detection mechanism unit 20 or the trip device senses the occurrence of a fault current and automatically triggers the switch to operate at a position where the switch 16 trips (open state). The lever 22 coupled to the upper end of the bimetal 21 by the bending of the bimetal 21 when the overcurrent is generated on the circuit causes the crossbar 23 to rotate so that the latch 14 ) Is released and tripped.

The temperature detection unit 30 is integrated to measure the ambient temperature and the internal temperature of the circuit breaker. The temperature detector 30 is provided with a temperature sensor. Thermocouples, temperature measuring resistors, thermistors (NTC, PTC, CTR), thermal ferrites, and metal thermometers can be applied to these temperature sensors.

The temperature sensor includes a first temperature sensor 31 installed to be exposed to the outside of the case 10 to measure the ambient temperature of the circuit breaker, a second temperature sensor (not shown) installed inside the circuit breaker to measure the internal temperature of the circuit breaker 32). At this time, the first temperature sensor 31 and the second temperature sensor 32 may be provided at a plurality of spaced apart positions. By providing the first temperature sensor 31 and the second temperature sensor 32 in plural, the ambient temperature OT of the circuit breaker and the internal temperature IT of the circuit breaker can be more accurately calculated. For example, the ambient temperature (OT) value can be obtained as an average value of values obtained from each external sensor. Alternatively, it may be set to the highest value or the lowest value among the measured values. The internal temperature (IT) value may also be set to one of an average value, a maximum value, and a minimum value of the values obtained from the respective internal sensors.

The first temperature sensor 31 may be installed in the insertion portion 33 formed in the case 10 such as a hole and the second temperature sensor 32 may be formed in a portion protruding inward of the case 10 A protrusion, or the like. It is preferable that the first temperature sensor 31 and the second temperature sensor 32 are installed in the vicinity of the detection mechanism 20. [ That is, the first temperature sensor 31 may be provided outside the detection mechanism unit 20, and the second temperature sensor 32 may be provided inside the detection mechanism unit 20. Here, the second temperature sensor 32 may be installed close to the bimetal 21.

A control unit is provided for various operations, determination, and control. This control unit may be configured by the MCU 35. [ When the temperature value measured by the temperature detector 30 is transmitted to the MCU 35 and the measured temperature value is higher than the predetermined reference temperature, the MCU 35 instructs the heat dissipating unit 40 to operate . For example, the external reference temperature, which is compared to the ambient temperature OT, is set at 40 占 폚, and the internal reference temperature, which is compared to the internal temperature IT, can be set at 70 占 폚. Accordingly, when the value of the ambient temperature OT measured by the first temperature sensor 31 exceeds 40 ° C, it is possible to issue a command to operate the heat dissipating means 40. Further, when the internal temperature IT measured by the second temperature sensor 32 exceeds 70 ° C, the heat radiation means 40 may be instructed to operate.

A power supply unit 45 may be provided. The power supply unit 45 is provided to supply power to the heat dissipating means 40 and each electric component. The power supply unit 45 may be connected to a three-phase circuit included in the circuit breaker for power supply. That is, it can be connected to a part of R, S, T phase to generate power. The power supply unit 45 may be provided with a transformer or an adapter for AC / DC conversion and voltage conversion.

A heat dissipating means (40) is provided to dissipate the heat inside the circuit breaker to the outside to reduce the internal temperature. The heat dissipating means 40 may be constituted by a fan. The heat dissipating means 40 can be operated by receiving power from the power supply unit 45. An On / Off command of the heat dissipating means 40 may be provided in the MCU 35.

The heat dissipating means (40) can be installed inside or outside the case (10). And may be provided inside the side wall of the case 10. The heat dissipating means (40) may be provided on both sides of the case (10). It is preferable that the heat dissipating means 40 is installed as close as possible to the portion where the detecting mechanism portion 20 is formed.

In the case 10, a plurality of slits or holes are formed in a portion where the heat dissipating means 40 is provided. So that the heat inside can be discharged to the outside through the vent portion 45. This heat release is accelerated by the heat dissipating means 40. Here, the vent portion 45 may be formed to be completely open so that the heat dissipating means 40 can be exposed.

A current detection unit 50 may be provided to measure the current flowing in each circuit. The current detector 50 may be connected to the three-phase circuit (R phase, S phase, and T phase) to detect the current flowing in each phase and transmit the detected current to the MCU 35. The MCU 35 can determine whether there is an abnormality in the circuit according to the current value measured by the current detector 50. [ Further, the heat dissipating means 40 can be operated according to the determination result. For example, when the current value measured by the current detecting unit 50 exceeds 105% of the rated current, the heat dissipating unit 40 can be operated. In this case, it can be used as a means for maintaining the normal operation time of the circuit breaker.

An A / D converter 34 may be provided between the temperature detector 30 and the MCU 35. The A / D converter 34 converts the temperature value measured by the temperature detector 30 to an analog value that can be processed by the MCU 35 when the measured temperature value is an analog value. An A / D converter 54 may be provided between the current detector 50 and the MCU 35. The A / D converter 54 converts the current value measured by the current detector 50 into an analog value, which is converted into a digital value that can be processed by the MCU 35.

The MCU 35, the power source unit 45, the A / D converters 34 and 54 and the like are shown only in the circuit diagram of FIG. 5 and not in the internal cross-sectional view of FIG. 4, And may be installed or assembled on a PCB circuit board.

The operation of the wiring breaker having the overheat prevention function according to the embodiment of the present invention will be described.

The first temperature sensor 31 of the temperature detector 30 measures the ambient temperature OT and transmits the measured value to the MCU 35. [ The second temperature sensor 32 of the temperature detector 30 measures the internal temperature IT and transmits the measured value to the MCU 35. Here, when the ambient temperature (OT) value or the internal temperature (IT) value is an analog value, it is converted into a digital value by the A / D converter (34). Further, the ambient temperature OT and the internal temperature IT can be measured at a plurality of positions, respectively.

The MCU 35 calculates the resultant value of the ambient temperature (OT) and the resultant value of the internal temperature (IT). For example, the ambient temperature (OT) result may be determined as the average, lowest or highest value of a plurality of measured ambient temperature (OT) values. This method can be applied equally to the internal temperature (IT) result value. On the other hand, the MCU 35 stores a reference internal temperature and a reference external temperature which are preset by the user. The MCU 35 compares the resultant value of the ambient temperature OT with the reference external temperature and commands the heat dissipating means 40 to operate when the resultant value of the ambient temperature OT is larger than the reference external temperature. Also, when the resultant value of the internal temperature IT is compared with the reference internal temperature, if the resultant value of the internal temperature IT is larger than the reference internal temperature, the command is issued to allow the heat dissipating means 40 to operate.

In addition, the MCU 35 compares the current value of each phase measured by the current detection unit 50 with the set mood current. Here, the set reference current is preset and stored by the user, and may correspond to 105% of the rated current, for example. If the current value of any phase is larger than the reference current, a command is issued to cause the heat dissipating means 40 to operate.

For example, suppose that the reference external temperature is 40 ° C, the reference internal temperature is 70 ° C, and the reference current is 105% of the rated current. The MCU 35 can instruct the heat radiating means 40 to operate when the following conditions are satisfied.

(1) Outside temperature (OT) If the result is more than 40 ℃

(2) If the internal temperature (IT) result is over 70 ℃

(3) When the current value of any phase is 105% or more of the rated current

At this time, the above three conditions can be combined with the AND or OR condition according to the user's setting.

According to the wiring breaker having the overheat prevention function according to the embodiment of the present invention, the temperature around the bimetal inside the breaker can be prevented from being overheated, thereby preventing the occurrence of interruption even during normal current application.

Further, there is an effect that the delay trip operation time due to the overcurrent can be normally maintained close to the reference temperature.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. That is, the scope of protection of the present invention should be construed according to the following claims, and all technical ideas which are within the scope of the same should be interpreted as being included in the scope of the present invention.

10 case 11 fixed contacts
12 Operational Contact 14 Latch
15 ARC SOHO section 16 Bend switch
17 Handle 18 Trip spring
19 Shaft 20 Detection Mechanism
21 Bimetallic 22 lever
23 crossbar 30 temperature detector
31 first temperature sensor 32 second temperature sensor
33 Insertion section 34, 54 A / D converter
35 MCU 40 Heat dissipation means
45 power supply unit 45 vent
50 current detector

Claims (8)

A temperature detector for detecting an ambient temperature of the circuit breaker with a first temperature sensor provided outside the case;
An MCU (Micro Controller Unit) which receives the ambient temperature measured by the temperature detector and compares the measured ambient temperature with a preset external reference temperature;
And a heat dissipating unit installed in a part of the case and operated under the control of the MCU. The circuit breaker according to claim 1, further comprising a power supply unit connected to the three-phase circuit to convert AC into DC, and to supply power to the MCU and the heat dissipating unit. The circuit breaker according to claim 1, wherein the heat dissipating means comprises a fan. The circuit breaker according to claim 1, wherein the case is provided with a plurality of slits or holes formed in a portion where the heat dissipating means is installed. The circuit breaker according to claim 1, wherein the temperature detector further comprises a second temperature sensor installed inside the case and measuring an internal temperature. 3. The circuit breaker of claim 2, further comprising a current detector connected to the three-phase circuit to detect a current flowing in each phase and transmit the detected current to the MCU. 6. The circuit breaker according to claim 5, wherein the MCU compares the internal temperature measured by the second temperature sensor with a predetermined internal reference temperature to operate the heat dissipating means. The circuit breaker according to claim 6, wherein the MCU compares the current value measured by the current detecting unit with a predetermined reference current to operate the heat dissipating unit.

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