JPH0740183Y2 - Overheat detection device for electrical equipment - Google Patents

Description

[Detailed Description of the Invention] [Field of Use of the Invention] The present invention relates to detection of overheating of electric equipment such as a switchboard and a transformer.

[Prior Art] One of the applicants converts overheating of an electric device into generation of gas and detects this gas with a gas sensor.
An overheat detection device for electric equipment was proposed. For example, JP-A-63-8
In Japanese Patent No. 1,232, it is proposed that hydrogen is absorbed by a hydrogen storage alloy, H ₂ is released by overheating, and the gas is detected by a gas sensor. Further, Japanese Patent Application Laid-Open No. 1-144,196 proposes that a gas cylinder is filled with H ₂ or the like, the plug is made of a low melting point alloy, and H ₂ is generated by overheating.

The present invention relates to improvements in such a device, and more particularly to the following improvements.

1) Hydrogen storage alloys and gas cylinders are expensive, and an inexpensive H ₂ generating means to replace them is developed.

2) In addition to H ₂ , the gas sensor is affected by ambient temperature and humidity and other miscellaneous gases such as alcohol, so an H ₂ detection circuit that is not affected by these will be developed.

3) Moreover, even if H ₂ itself exists as an exogenous gas that is unrelated to overheating, it should not cause a false alarm.

4) It becomes unnecessary to set the output for each gas sensor.
That is, since the gas sensor has variations in output, it is necessary to set the output for each sensor. This imposes a heavy burden on the assembly of the device.

In addition, Japanese Patent Application No. 63-254,494 (Japanese Patent Application Laid-Open No. 2-161,326) is a prior application, in which an acid such as sulfuric acid is contained in a container such as glass and the container is destroyed by overheating, and the acid flowing out from the container is treated with metal. It is proposed to generate H ₂ by reacting with. However, this prior application does not consider the above points 2) to 4).

[Problem of Invention] The basic problem of this invention is as follows.

1) H without heat storage alloy or gas cylinder
₂ can be generated, and the means for generating H ₂ can be simplified.

2) It should be possible to detect H ₂ without being affected by the temperature and humidity of the atmosphere and the influence of miscellaneous gas, eliminate false alarms, and surely detect overheating.

3) Also, prevent false alarms from occurring even if H ₂ itself exists as an exogenous gas.

4) It becomes unnecessary to set the output for each gas sensor.

5) Furthermore, the detection signal is prevented from being affected by the distance from the H ₂ generating means to the H ₂ sensor.

In addition to the above, 6) the object of claim 2 is to provide H ₂ selectivity to the gas sensor to further enhance the reliability of detection.

[Constitution of device] In this device, at a position where there is a danger of overheating of electric equipment,
With installation of H ₂ generation unit 2 in combination with the acid-resistant container and the metal containing the acid, for detecting of H ₂ from H ₂ generating unit 2, the resistance value by adsorption of the H ₂ gas is changed An H ₂ sensor 3 using a metal oxide semiconductor is provided, an AD converter 13 for AD converting the output of the H ₂ sensor 3, a memory 15 for storing the output of the AD converter 13 as a reference value, and a memory 15 Reference value stored in AD converter 13
Then, the output of the H ₂ sensor 3 newly AD-converted is compared to H ₂
With H ₂ detecting means 19 for detecting, H ₂ detecting means 19 H
An H ₂ detection circuit configured with a timer 17 for updating the reference value stored in the memory 15 at a predetermined interval when ₂ is not detected is provided to detect overheating from the generation of H ₂ due to overheating of electrical equipment. To do.

With this configuration, when the electric device is overheated, for example, the acid in the container boils, the container is destroyed by vapor pressure or the like, and H ₂ is generated by reacting with the surrounding metal. On the other hand, the output of the H ₂ sensor is AD
After conversion, an output in a situation in which H ₂ is not considered to be generated is selected as a reference value and updated at a predetermined interval. Newly
The output of the AD-converted H ₂ sensor is compared with a reference value, and H ₂ is detected when the ratio or difference from the reference value changes by a predetermined value. When H ₂ is not detected, the timer is used to update the reference value of the memory at predetermined intervals. Therefore, the output when H ₂ is not generated from the H ₂ generating means is used as the reference value.

When the overheat detecting device starts to operate and stores the first reference value in the memory, normally H ₂ is not generated. Therefore the initial value of the reference value as the output of the H ₂ sensor when the H ₂ is not generated, and updates the reference value on the condition that does not detect the subsequent H _2. Therefore no H ₂ is generated from H ₂ generating means, i.e. the electrical equipment is not superheated, H when ₂
The output of the sensor is stored as a reference value.

Detection of H ₂ is carried out by comparison between the output and the reference value of the H ₂ sensor,
Since the reference value is automatically generated, it is not necessary to adjust the output of the H ₂ sensor to set the H ₂ detection point. Further, when the ambient temperature and humidity change, or when a noisy gas is generated in the surroundings, the output of the H ₂ sensor changes accordingly, and the reference value also changes accordingly. This is because changes in temperature and humidity and changes in the concentration of miscellaneous gases in electric devices are generally slow, and the reference value can follow them. Therefore, it is possible to compensate for the influences of ambient temperature and humidity and miscellaneous gas. Similarly, exogenous H ₂
Is generated, that is, H ₂ is generated from other than the H ₂ generation means,
Even when diffused in the electric equipment, the reference value changes following it and is not affected by exogenous H ₂ . This is because exogenous H ₂ is usually generated slowly and the change in concentration is gradual, and the reference value follows this.

If the effect of temperature and humidity is compensated and the effect of miscellaneous gas and exogenous H ₂ is simply removed, it is possible to differentiate the output of the H ₂ sensor, for example. The rate of increase in the concentration of miscellaneous gas and exogenous H ₂ is slow, and the fluctuation of temperature and humidity is usually a slow phenomenon of one day cycle, and if they are differentiated, their influence is eliminated. However, the differentiation affects the distance between the H ₂ generating means and the H ₂ sensor, the direction of the air flow in the electric device, whether the electric device is sealed or opened, and the internal volume of the electric device. For example, if the distance between the H ₂ generating means and the H ₂ sensor is large and the internal volume of the electric device is large, the differential signal is small, and if the distance is small and the internal volume is small, the differential signal is large. By comparing the output of the reference value and H ₂ sensor contrast, to the reference value in the timer is updated, the output of the H ₂ sensor may be changed in response of H ₂ from H ₂ generating means . And for example H ₂
Even if the distance between the sensor and the H ₂ generating means is large and the response is slow, the diffusion of H ₂ is completed in the electric device by the time the reference value is updated, and the generation of H ₂ can be detected. Therefore, overheating can be detected without being affected by the air flow or the distance from the H ₂ generating means.

Here, as H ₂ sensor, a metal oxide semiconductor such as SnO ₂ and an In ₂ O _3, poisoned by steam of organic silicon compound, H ₂
It is preferable that the sensitivity to gases other than the above is removed (Claim 2). The metal oxide semiconductor gas sensor is the cheapest of various gas sensors, and the auxiliary circuit is simple. Metal oxide semiconductor gas sensors generally do not show gas selectivity, but only in the case of H ₂ sensors, they show exceptionally high selectivity to H ₂ .

[Example] An example is shown in Figs. 1 to 4. In FIG. 1, 1
Is a switchboard, and 2 is a means for generating H ₂ installed in the switchboard 1 near the electric equipment GCB. The H ₂ generating means 2 is a disposable type and is replaced every time H ₂ is generated.

The H ₂ generating means 2 is configured, for example, to enclose sulfuric acid or the like in an acid resistant container, destroy the container at a predetermined temperature and react with a metal such as zinc to generate H ₂ . By doing so, a large amount of H ₂ can be generated at a predetermined temperature without using a high pressure cylinder or the like.

Returning to FIG. 1, 3 is an H ₂ sensor, in which SnO ₂ is used as a metal oxide semiconductor, and this is poisoned in a vapor of an organic silicon compound such as trimethyl silicon chloride to convert it to a gas other than H _2. The sensitivity shall be removed. The conditions for the poisoning treatment are arbitrary. Reference numeral 4 is an H ₂ detection circuit, 5 is an external terminal for transmitting a detection signal, and 6 is a detection circuit box, which also has a role of blocking electromagnetic waves from electrical equipment and the like in the switchboard 1.

FIG. 2 shows the configuration of the H ₂ detection circuit 4. In the figure,
7 is a power source, 8 is a transformer circuit, 3 is the above H ₂ sensor, 10
Is the heater, 9 is a metal oxide semiconductor for H ₂ detection,
Here, SnO ₂ poisoned with an organosilicon compound is used. Reference numeral 11 is a load resistance of the H ₂ sensor.

12 is a microcomputer for signal processing, 13 is an AD converter, 14 is a memory for storing the sensor output V (voltage of the load resistance 11) at each time point, and 15 is a sensor output when H _{2 is} not generated A memory for storing the value Vstd. 16, 17 and 18 are timers, and the timer 16 is for stopping the detection of H ₂ for about 10 minutes to 3 hours at the start of use of the switchboard 1. The timer 17 is for reading the reference value Vstd. Further, the timer 18 is for providing a waiting time for detecting H ₂ . The value of the memory 15 is updated by the timer 17 every 1 minute to 1 hour, for example. Although the memory 15 stores the instantaneous value of the sensor output V at the time of updating here, it may store the average value or the minimum value of the sensor output in the section determined by the timer 17 and the (previous section). Reference numeral 19 denotes H ₂ detection means, which is a sensor output V and a reference value Vstd.
H ₂ is detected from the ratio and difference with In the embodiment, V is 1.5
It is assumed that H ₂ is generated above Vstd. Hereinafter, this constant (here, 1.5) is set to K. H ₂ detection signal of the detection means 19
Vout is transmitted from the external terminal 5 to the control room or the like. Reference numeral 20 is a reset terminal of the detecting means 19.

The operation of the apparatus is shown in FIGS. 3 and 4. When the use of the switchboard 1 is started, the sensor 3 starts operating. Here, the detection of H ₂ is stopped by the timer 16 until the atmosphere in the switchboard 1 becomes stable and the operation of the sensor 3 becomes stable. When the operation of the timer 16 is finished, the detection of H ₂ is started.

Next, when abnormal overheating occurs, a predetermined amount of H ₂ is released from the H ₂ generating means 2. H ₂ diffuses to the top of switchboard 1
₍₂₎ The resistance value is decreased by coming into contact with the sensor 3 and adsorbing to the metal oxide semiconductor 9. The time until the change in the resistance value of the H ₂ sensor 3 is completed after H ₂ is generated by the H ₂ generating means 2 depends on the distance from the sensor 3, etc.
It was usually within 1 minute and outside. The degree of change in resistance is 4
It was about 20 times. An example of this change is shown in FIG.
The power supply voltage here is 5V, and the sensor output V is K · Vstd.
After exceeding the delay time, after a delay time determined by timer 18, K again
It was confirmed that, exceeds the Vstd are to detect the H _2.

Change in the output of the H ₂ sensor 3 due to H ₂ evolution is large, distinguishable from slow change in the sensor output due to temperature and humidity and miscellaneous gas around. Therefore, in the H ₂ detection circuit 4, the sensor output V when H ₂ does not occur is stored in the memory 15 as the reference value Vstd,
It is updated every 8 minutes, which is the time determined by the timer 17. The reference value Vstd is not updated when H ₂ is generated. Further, the reference value Vstd to be stored is the average of the sensor output V at the time of updating for 2 seconds, but may be the average value of the interval determined by the timer 17 or the like. The generation of H ₂ is a ratio of the sensor output V being K or more than the reference value Vstd (here, 50%).
Start from the fact that it has increased. Further, in order to prevent malfunction due to temporary fluctuation of the sensor output V,
Timer exceeds 18 seconds after K exceeds V ・ Vstd, 5 seconds ~
A waiting time of about 1 minute, here 10 seconds is provided. Then, even after the waiting time has elapsed, if V exceeds K · Vstd, H ₂ is detected. When H ₂ is detected, this is transmitted from the external terminal 5 and the detection signal is continuously transmitted until it is reset after the inspection of the abnormal overheated portion.

In this way, H ₂ can be detected without adjusting the detection point for each individual sensor 3. In addition, it is possible to automatically compensate for the effects of ambient gas and temperature and humidity.

Although a specific embodiment has been described here, the timer 16 for setting the delay time at the start of the operation and the timer 18 for removing the influence of the temporary fluctuation of the sensor output may not be provided.

[Advantages of the Invention] In this invention, 1) the acid is contained in the container, and when the container is overheated, the container is destroyed and reacts with the surrounding metal to generate H _2. Therefore, a simple H ₂ generating means is used. It does not require expensive hydrogen storage alloys or gas cylinders.

2) Since the reference value stored in the memory is compared with the output of the H ₂ sensor, it is not affected by ambient temperature / humidity and miscellaneous gas. When the ambient temperature and humidity change or when a noisy gas is generated, the reference value also changes accordingly, and it does not affect the detection of overheating. Moreover, even if H ₂ itself is generated as an exogenous gas,
If the H ₂ generation pattern is different from the H ₂ generation pattern from the H ₂ generation means, no false alarm will occur. For these reasons, overheating can be reliably detected without false alarms.

3) comparing the output of the reference value and H ₂ sensor, since the reference value by reading the output of the H ₂ sensor in a situation that does not occur in H _2, is necessary to set the output individually for each gas sensor There is no.

4) The reference value is compared with the output of the H ₂ sensor, and the reference value is updated at a predetermined interval. Therefore before updating the reference value, H ₂ sensor may be responsive in H ₂ generated from the H ₂ generation unit. Therefore, even if the distance from the H ₂ generating means to the H ₂ sensor is large, or even if the airflow is flowing in a direction different from the H ₂ sensor side, if the output of the H ₂ sensor changes before the reference value is updated. , Overheat can be detected.

According to claim 2, 5) H ₂ selectivity is given to the gas sensor to further improve the detection reliability.

[Brief description of drawings]

Layout view of FIG. 1 embodiment, FIG. 2 is a circuit diagram of H ₂ detection circuit, FIG. 3 is the operation flowchart, FIG. 4 is an operation characteristic diagram of the embodiment. In the figure, 1 ... Switchboard, 2 ... H ₂ generating means, 3 ... H ₂ sensor,
4 ... H ₂ detection circuit. 12 …… Microcomputer 13 …… AD converter 15 …… Memory 17 …… Timer 19 …… H ₂ detection means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Asada 47 Umezu Takaunecho-cho, Ukyo-ku, Kyoto Prefecture Nissin Electric Co., Ltd. Within the corporation

Claims (2)

[Scope of utility model registration request] 1. A at risk one point of electrical equipment overheating, as well as installation of H ₂ generation unit 2 in combination with the acid-resistant container and the metal containing the acid, H ₂ from the H ₂ generation means 2 for detecting, H ₂ gas and H ₂ sensor 3 resistance using a metal oxide semiconductor which changes by the adsorption provided for, H ₂ AD converter 13 for output to the AD conversion of the sensor 3
And the memory 15 for storing the output of the AD converter 13 as a reference value, the reference value stored in the memory 15 and the output of the H ₂ sensor 3 newly AD-converted by the AD converter 13 are compared to determine H ₂ . The H ₂ detecting means 19 for detecting and the memory 15 at a predetermined interval when the H ₂ detecting means 19 does not detect H _2.
An overheat detection device for an electric device, which is provided with an H ₂ detection circuit configured with a timer 17 for updating the reference value stored in the above, and detects the overheat from the generation of H ₂ accompanying the overheating of the electric device. The method according to claim 2, wherein the H ₂ sensor 3, characterized in that as its sensitivity H ₂ sensor to remove the metal oxide semiconductor is treated with an organic compound vapor of silicon H ₂ than to gases, according Item 2. An overheat detection device for an electric device according to Item 1.