JP3355920B2 - Abnormal overheat detector for closed switchboard - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting abnormal overheating of a main circuit conductor connecting portion in a closed switchboard.

[0002]

2. Description of the Related Art Monitoring the heat generation state of various electric devices is one of excellent monitoring means for detecting abnormalities of electric devices at an early stage and preventing an accident from occurring. In the related art, a method is conventionally used in which a point thermometer capable of measuring the temperature of an arbitrary point in a device is installed. However, in the case of a so-called control panel or a closed switchboard used for power control, the size of the panel is considerably large, and a portion that generates heat is often present in a certain range. Therefore, appropriate monitoring cannot be expected because many point thermometers are required. Therefore, a method of measuring and monitoring the surface temperature of an object using infrared rays emitted from a wide area that generates heat has been conventionally proposed.

FIG. 8 is an explanatory view showing a state of attachment of a device similar to a conventional power equipment temperature inspection device disclosed in Japanese Patent Application Laid-Open No. 62-81927, and FIG. 9 is a block diagram thereof. In the figure, reference numeral 15 denotes a power control panel in which power devices or connection conductors are housed, 25 denotes a power semiconductor mounted inside the power control panel 15, 26 denotes a resistor, and 27 denotes a resistor.
Is a transformer. Here, the power semiconductor 25 and the resistor 2
6. The transformer 27 is shown only as an example of a power device that generates heat. Reference numeral 1 denotes a main circuit conductor for connecting the above-described power devices, and reference numeral 2 denotes a connection portion of the main circuit conductor 1.

[0004] 16 and 17 are power control boards 15 respectively.
An x-axis position detector and a y-axis position detector for detecting the positions of the x-axis and y-axis coordinates in FIG.
A power detector 14 detects an operating state of the power control panel (for example, power consumption of each part of the control panel), and an infrared temperature detection device 14 is mounted inside the power control panel 15 and detects temperature in a non-contact manner.
Reference numeral 19 denotes a temperature measured by the infrared temperature detecting device 14 as an XY parameter detected by the X and Y axis position detectors 16 and 17, using an operation state of the power device detected by the power detector 18 as a parameter.
A rewritable memory which stores and updates the initial operation value (also referred to as an initial memory value), new data for the old data inspection value, and the like for each coordinate. An alarm setting device for presetting an allowable limit value of a temperature difference, an arithmetic processing device for calculating an operation state for each power device from the detected data and the initial memory value, checking for an abnormality and outputting the calculation result to the outside. , 22 are displays for displaying the detected data based on the output of the calculation result from the processing unit 21.

[0005] Reference numeral 23 denotes an alarm device which issues an alarm when the temperature difference between the initial memory value and the detected temperature value exceeds the above-mentioned permissible limit value, and 24 denotes an external recorder or other measuring device (not shown). This is a signal converter that can take out a signal. In FIGS. 8 and 29, the positions of the x-axis and the y-axis of the infrared temperature detector 14 can be moved, and the X-axis position detector 16 and the Y-axis position detector 17 of the infrared temperature detector 14 are attached. An x-axis movable guide rail and a y-axis movable guide rail.

Next, the operation of the conventional device based on the above configuration will be described. FIG. 10 shows a state of temperature detection by infrared rays in an image image. Reference numeral 30 denotes a heating portion of the connection portion 2 of the main circuit conductor 1. The infrared temperature detector 14 is sequentially moved along the x-axis movable guide rail 28 and the y-axis movable guide rail 29 in the x-axis and y-axis directions inside the power control panel 15 to detect the x-axis and y-axis positions and the temperature. I do. At this time, the load state is simultaneously detected by the power detector 18 mounted in the power control panel 15.

A load state detected for each moving position, the position and temperature of the infrared temperature detecting device 14 are input to the arithmetic processing unit 21, and the relationship between the load and the heat generation temperature as shown in FIG. Is compared with the data of the rewritable memory, which is measured and stored in the normal state, as a parameter. The calculated data is displayed on the display 22. If an abnormal temperature is detected, an alarm 23 issues an alarm, and the signal converter 24 sends a signal to an external device (not shown). I do.

[0008] The above conventional overheat detecting device includes a power semiconductor 25 in a power control panel 15 and the like.
It is suitable when emphasis is placed on the detection of abnormal overheating of a specific power device housed in a power distribution panel having a small number of partition plates in the panel.
However, in the case of a closed switchboard, most of the portions requiring abnormal overheat detection are the connection portions 2 of the main circuit conductors 1. Since the main circuit conductor connection portions 2 are provided on each closed switchboard, the abnormal overheat detection is not performed. There will be many sites that need it. In addition, the periphery of the connection portion 2 is often surrounded by a partition plate, and it is not possible to scan the position of one infrared detection device 14 and detect abnormal overheating of all desired main circuit conductor connection portions 2. It was difficult. Therefore, a plurality of infrared temperature detectors 14 are required in one switchboard. Further, the connection portion 2 is concentrated in a specific range of several places in the panel. If it is specified that abnormal overheating is occurring in any one of these several ranges, abnormal overheating occurs. This is sufficient information for performing inspection and repair after the detection, and there is a situation that it is not necessary to strictly identify the location where the occurrence occurs.

[0009]

Under the circumstances described above, even if the above-mentioned conventional abnormal overheat detecting device is applied to a closed switchboard, the abnormal overheat detecting device becomes complicated and expensive, but there is much waste. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a simple and inexpensive abnormal overheat detecting apparatus which can detect the occurrence of abnormal overheating in a main circuit conductor connecting portion of a closed switchboard. It is an object.

[0011]

According to the present invention, there is provided an apparatus for detecting abnormal overheating of a closed switchboard, comprising: an infrared detector for measuring an area including a connection portion of a plurality of main circuit conductors in the closed switchboard; A current measuring converter for detecting a current I flowing through the sensor, an external air temperature detector for measuring an external air temperature T around the closed switchboard, and an average temperature Tav of the measurement visual field when the connection portion of the main circuit conductor is normal. In addition to the calculation, the temperature difference (Tav-T) from the outside air temperature T and the current I
And the difference between the average temperature Tav of the measurement field of view and the outside air temperature T (Tav−) using the outputs of the infrared detection device, the current measurement converter, and the outside air temperature detector as inputs.
A computing unit that computes the current value of T), compares the stored normal relationship with the current value, and outputs a predetermined output when the difference between the normal value and the current value exceeds a predetermined range. It is composed of

[0012]

Further, the arithmetic unit passes the measured value of the current flowing through the main circuit conductor through a first-order lag filter having a time constant corresponding to the thermal time constant of the main circuit conductor, or closes the measured value of the outside air temperature to this closed value. It is used for calculation via a first-order lag filter having a time constant corresponding to the thermal time constant of the switchboard.

[0014]

[0015]

[0016] Further, an infrared detection device having a measurement field of view including a connection portion of a plurality of main circuit conductors in a closed switchboard,
A current measuring converter for detecting a current I flowing through the main circuit conductor, an external temperature detector for measuring an external temperature T around the closed switchboard, and an average of the measurement fields of view in a state where the connection portion of the main circuit conductor is normal. The relationship between the infrared intensity, the external temperature T, and the current I is stored, and the outputs of the infrared detector, the current measuring converter, and the external temperature detector are input.
By comparing the stored normal relationship with the current value,
And an arithmetic unit for performing a predetermined output when the difference between the normal value and the current value exceeds a predetermined range.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a configuration diagram showing an embodiment of an abnormal overheat detection device for a closed switchboard according to the present invention, and reference numeral 50 denotes a housing of the closed switchboard. 1 is a main circuit conductor (for example, a copper plate bus) arranged inside the closed switchboard 50;
Reference numeral 2 denotes a connection portion of the main circuit conductor 1, and reference numeral 3 denotes an internal partition of the closed switchboard 50. Reference numeral 4 denotes an infrared detector according to the present invention, which comprises a thermopile, an infrared detector 4a having a measurement field of view 7, and an amplifier 4b for amplifying the voltage output from the infrared detector 4a. The infrared detecting device 4 measures the average temperature of the intensity of infrared light emitted from an object in the measurement visual field 7. Reference numeral 5 denotes an arithmetic unit for calculating an output signal of the amplifier 4b, which has a function of storing data and an arithmetic operation. The infrared detector 4a is fixedly installed at a position where infrared rays from a wide area including all the main circuit conductor connections 2 to be monitored can be detected in the measurement field of view 7. Reference numeral 6 denotes an external temperature detector that measures the temperature around the closed switchboard 50. Reference numeral 8 denotes a current transformer for measuring the current I flowing through the main circuit conductor 1 in the measurement visual field 7, and 9 denotes a current measuring converter connected to the current transformer 8 for measurement. The output of the infrared detector 4, the converter 9 for current measurement, and the output of the external air temperature detector 6 are input to the arithmetic unit 5.

FIG. 2 is a characteristic explanatory diagram for explaining the operation principle of the apparatus for detecting abnormal overheating of a closed switchboard shown in FIG. FIG.
The horizontal axis indicates the current value I (output of the current measurement converter 9) flowing through the main circuit conductor 1, and the vertical axis in FIG. 2A indicates the true temperature t of one connection portion 2 of the main circuit conductor 1. Is shown. Reference numeral 30 denotes a characteristic line indicating a true temperature t of the connection portion 2 of the main circuit conductor 1 in a normal state. 31 is a characteristic line showing an example of the temperature t when the connection portion 2 is abnormally overheated. As shown in the figure, the temperature 31 of the temperature of the conductor connection portion 2 with respect to the current flowing through the main circuit conductor 1 when abnormal overheating occurs in the conductor connection portion 2 as shown in FIG. , As compared with the characteristic 30 in the normal state. Of course, although not shown in FIG. 2 (a), these characteristic lines 30 and 31 greatly fluctuate depending on the external temperature T, and all the connection parts 2 must be measured one by one. It is difficult to detect an abnormality only by measuring the characteristics of the data.

In FIG. 2B, the horizontal axis represents the main circuit current I, and the vertical axis represents the average temperature T in the measurement visual field 7 detected by the infrared detector 4.
The difference between av and the outside temperature T is shown. As shown in FIG. 2B, the average temperature T in the measurement visual field 7 of the infrared detector 4
av and the temperature difference (Ta) between the outside air temperature T outside the closed switchboard 50.
Regarding the characteristics of vT) with respect to the main circuit current I, the characteristics in the normal state 32 and those in the abnormal overheat generation state 33 are different. These characteristics 32 and 33 do not fluctuate significantly even when the external temperature T changes. This is because if the external temperature T changes, the average temperature Tav also changes accordingly, and the difference does not change.

FIG. 2B shows a normal state of the arithmetic unit 5.
The temperature difference characteristic 32 is stored. Then, the output of the infrared detector 4, the main circuit current measurement value I, and the external air temperature measurement value T are input. The arithmetic unit 5 calculates an average temperature Tav, and calculates a temperature difference (Tav) obtained from the input measured values.
By comparing the characteristic of −T) with the main circuit current I and the stored characteristic 32 and calculating the difference, the presence or absence of abnormal overheating in the measurement visual field 7 is detected. FIG. 2 (b)
Reference numeral 40 denotes an abnormal overheat determination line which is set by adding a predetermined bias to the characteristic 32 in order to prevent a malfunction of the abnormality determination due to a measurement error or the like. In the actual configuration of the apparatus, it is better to use the abnormal overheat determination line 40 without using the characteristic line 32 as a criterion for determination. In this case, what the arithmetic unit 5 stores is the characteristic of the abnormal overheat determination line 40. In the above description, the arithmetic unit 5 calculates the average. However, an infrared detector of a type that detects the average temperature within the visual field of the infrared detection device 4 can be used.

Embodiment 2 FIG. FIG. 3A shows the main circuit current I.
3 shows a state of a time change of the temperature t of the conductor connection portion 2 and other time in a normal case with respect to the fluctuation of the temperature. Temperature t of conductor connection 2 with respect to change in current I flowing through main circuit conductor 1
Changes are time delays 61, 62 (time constants t1, t2)
Therefore, when calculating the difference between the average temperature Tav in the measurement visual field 7 in the normal state and the temperature difference between the outside air temperature T and the main circuit current I, if the difference is normal, Due to the delay, a state exceeding the abnormal overheat determination line 40 (indicated by 99 in FIG. 3) occurs, and a case may be erroneously determined to be abnormal. FIG. 3B shows a temporal change in temperature and the like before and after the occurrence of an abnormality in the conductor connection portion 2. As shown in FIG. 3 (b), a time condition is included in the condition for judging abnormal overheating, and an abnormal condition is output only when a state in which it is possible to determine that an abnormality has occurred has continued for a predetermined time 63 or more. It is necessary to keep it. Here, the time 63 is a time longer than either of the times 61 and 62.
It is well known that the time constants t1 and t2 are about 1/3 of the times 61 and 62. Incidentally, in a general closed switchboard, t1 and t2 are about several tens of minutes.

In the above description, it has been described that the infrared detector 4 detects the average temperature of the object in combination with the arithmetic unit 5 and compares the average temperature with the temperature data.
Similar results can be obtained by comparing the infrared intensity. In this case, the vertical axis in FIG. 2A is read as infrared intensity.

Embodiment 3 FIG. FIG. 4 is a partial block diagram of an overheat abnormality detection device for a closed switchboard according to another embodiment, and FIG. 5 is a time chart for explaining the operation of the block diagram of FIG. Parts not described in FIG. 4 are the same as those in FIG. Reference numeral 42 denotes a first-order lag filter circuit for delaying the detection signal I of the main circuit current, which has a time constant of t1 with respect to a current decrease and a time constant of t2 with respect to a current rise. Here, t1 and t2 are the same as t1 and t2 shown in the second embodiment. Since the current signal I is used for calculation after passing through a first-order lag filter having the same time constant as the temperature change time constant of the conductor connection portion 2, FIG.
As shown in 41, the abnormal overheat determination line does not suddenly change, and the possibility that a false alarm is issued is reduced. Of course, the temperature change is not strictly a first-order lag type, but a practically sufficient approximation can be obtained. In addition, since the change in the average temperature Tav of the conductor connection portion 2 has a delay of about 10 to 30 minutes with respect to the change in the external air temperature T, the detected external air temperature T is similarly calculated via the first-order lag filter. By using this, more accurate determination can be made.

Embodiment 4 When the main circuit conductor 1 is made of, for example, aluminum, the infrared emissivity of aluminum is low, and therefore, the infrared radiation emitted from the switchboard internal partition plate 3 detected as a background in the measurement visual field 7 of the infrared detector 4 causes There is a possibility that the S / N ratio of the detection signal decreases and stable measurement cannot be performed. In such a case, as shown in FIG. 6, the surface 11 of the conductor connection portion 2 or the main circuit conductor 1 in the vicinity of the conductor connection portion 2 is subjected to a coating 11 or a resin coating process 12 to increase the infrared emissivity. If it is, infrared detecting device 4
The S / N ratio of the temperature data of the conductor connection portion 2 can be improved with respect to the average temperature detected in the field of view 7.

Embodiment 5 FIG. FIG. 7 shows another embodiment of the present invention. Note that parts not described in the figure are the same as those in FIG. FIG. 7 shows an example in which one computing unit 5 is shared by a plurality of infrared detectors 4, a plurality of current transformers 8 for measurement, and a plurality of converters 9 for current measurement installed inside a plurality of closed switchboards 50. Show. A switch 13 capable of selecting and outputting an arbitrary input signal from a plurality of input signals from each sensor is installed, and a plurality of normal temperature characteristics corresponding to a plurality of visual fields are stored, and By extracting and using the stored data corresponding to the selected sensor, one arithmetic unit 5 can detect abnormal overheating of the plurality of measurement fields 7. In the above description, detection of overheating of the connection portion of the main circuit conductor has been described.
It goes without saying that it can be used for objects other than conductors.

[0026]

Since the present invention is configured as described above, it has the following effects.

The measurement field of view of the infrared detector 4a is fixed to an area 7 including the main circuit conductor connection portion 2, the average temperature in the field of view is measured, and the location of the conductor connection portion where an abnormality has occurred is specified for each measurement field of view. This eliminates the need for the infrared detector to have a function of scanning the temperature measurement position, so that a simple device configuration can be achieved. Also, the infrared detector does not require an image processing function, and is small and inexpensive, such as a thermopile. Devices can be applied. Therefore, the occurrence of abnormal overheating and the location of the abnormality requiring repair can be realized by a simple and inexpensive device.

[0028]

The arithmetic unit may use the measured value of the current for calculation after passing through a first-order lag filter corresponding to the thermal time constant of the conductor, or may use the measured value of the external air temperature as the heat value of the closed switchboard. Since the calculation is performed via the first-order lag filter corresponding to the time constant, it is possible to more accurately determine overheating.

[0030]

[0031]

Further, since the measurement result of the infrared intensity is used as it is without converting it into a temperature, the determination can be further simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a temperature overheat detection device according to Embodiment 1 of the present invention.

FIG. 2 is a characteristic explanatory diagram for explaining the operation of the abnormal overheating detection device of FIG. 1;

FIG. 3 is an explanatory diagram of a change in a temperature of a conductor connection portion with respect to a change in a main circuit current.

FIG. 4 is a partial configuration diagram of a temperature overheat detection device according to a second embodiment of the present invention.

FIG. 5 is a timing chart for explaining the operation of the block diagram of FIG. 4;

FIG. 6 is a diagram showing a coating and coating process on a main circuit conductor surface.

FIG. 7 is a configuration diagram of a temperature overheat detection device according to Embodiment 2 of the present invention.

FIG. 8 is a configuration diagram of a conventional temperature detection device.

FIG. 9 is a block diagram of the temperature detection device of FIG.

FIG. 10 is an explanatory diagram of a temperature detection state in FIG. 8;

FIG. 11 is an explanatory diagram showing a relationship between a temperature and a load in the temperature detection of FIG. 8;

[Explanation of symbols]

1: main circuit conductor 2: main circuit conductor connection part 3: switchboard internal partition plate 4: infrared detector 4a: infrared detector (using thermopile) 4b: voltage amplifier 5: arithmetic unit 6: external temperature detector 7: measurement field of view (Field of view of infrared detector) 8: Current transformer for measurement 9: Converter for current measurement 12: Covering portion made of resin or the like 13: Switching unit 14: Infrared temperature detection detector 15: Power control panel 18: Power detector 19 : Rewritable memory 20: alarm setting device 21: arithmetic processing unit 22: display device 23: alarm device 24: signal converter 30: normal condition characteristics 31: abnormal heating characteristics 32: normal status characteristics 33: Characteristics of abnormal state 40, 41: abnormal overheat determination line 50: closed switchboard 61, 62: delay time 63: predetermined time t1, t2: time constant

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-30637 (JP, A) JP-A-5-30640 (JP, A) JP-A-52-120348 (JP, A) JP-A 64-64 1408 (JP, A) JP-A 3-127446 (JP, U) JP-A 60-158130 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/00 H02H 5 / 00,5 / 04

Claims (3)

(57) [Claims] 1. A fixedly installed infrared detecting device having a measurement field of view including a connection portion of a plurality of main circuit conductors in a closed switchboard, and a current measuring converter for detecting a current I flowing through the main circuit conductor. An external air temperature detector that measures an external air temperature T around the closed switchboard; and a temperature difference (Tav−) between the average air temperature Tav of the measurement visual field and the external air temperature T in a state where the connection portion of the main circuit conductor is normal. T) and the current I flowing through the main circuit conductor are stored, and the average temperature Tav of the measurement field of view is input using the outputs of the infrared detector, the current measuring converter, and the external air temperature detector as inputs.
And the difference (Tav-T) from the external temperature T is calculated, and compared with the stored normal relationship, a predetermined output is output when the difference from the normal exceeds a predetermined range. An abnormal overheating detection device for a closed switchboard, comprising: 2. An arithmetic unit measures a current flowing through a main circuit conductor.
Value with a time constant corresponding to the thermal time constant of the main circuit conductor
Either via a second-order lag filter or by measuring the external temperature
The measured value has a time constant corresponding to the thermal time constant of this closed switchboard.
After either passing through a first order lag filter
2. The apparatus for detecting abnormal overheating of a closed switchboard according to claim 1, wherein the apparatus is used for calculation . 3. Connection of a plurality of main circuit conductors in a closed switchboard
The fixed area of the infrared detector
And a power supply for detecting a current I flowing through the main circuit conductor.
Flow measurement transducer and the outside air temperature T around the closed switchboard.
The connection between the external temperature detector to be measured and the main circuit conductor is
Average infrared intensity of the measurement field of view in normal condition
Relationship between external temperature T and current I flowing through the main circuit conductor
And the infrared detector, the ammeter
Measuring converter, the output of the external temperature detector as input,
Compared to the stored normal relationship,
An arithmetic unit that outputs a predetermined output when the difference exceeds a predetermined range;
An abnormal overheat detection device for a closed switchboard, comprising: