JPH0218643Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> This invention relates to a condensation prevention device for a closed switchboard for the purpose of energy saving and dew condensation prevention.

<Prior Art> When condensation occurs inside a closed switchboard (hereinafter simply referred to as the board), it has negative effects such as accelerating the deterioration of the insulation of electrical equipment.

For this reason, conventional methods have been to install an electric heater inside the panel and manually turn it on and off, or to install a humidity sensor inside the panel and use it in combination with automatic control, or to discharge corona discharge on the surface of an insulator when its insulation deteriorates. As a result, methods such as operating an electric heater when insulation deterioration is detected have been adopted.

By the way, the insulation resistance of an insulator generally decreases as the temperature rises when the relative humidity is constant.
Conversely, the lower the temperature, the higher it becomes.

This is also clear from the following experiment.

In other words, in this experiment, a pair of electrodes were placed at a certain distance on phenolic resin, which is a type of insulator, and the insulation resistance between the two electrodes was measured at a relative humidity of 80% (constant). 1000MΩ,
At a temperature of 40°C, it showed a value of 400MΩ.

<Problem that the invention aims to solve> The results of this experiment show that even when the temperature is low and humidity is high, such as at night in winter, the insulation resistance of insulators increases, so there is no need to run electric heaters or dehumidifiers. However, if the humidity sensor were used for control as in the past, an electric heater or dehumidifier would be operated, which would waste power.

In addition, in the case of the conventional technology using the above-mentioned insulation deterioration sensor, insulation deterioration that is not accompanied by corona discharge cannot be detected, and when this sensor is activated, dielectric breakdown of the insulator (flash over) occurs due to the occurrence of corona discharge. There are various problems such as the risk of causing dielectric breakdown and making it difficult to prevent dielectric breakdown.

<Means for solving the problem> In order to solve the above points, this proposal uses an insulation resistance sensor in which a pair of electrodes are arranged on an insulator at a constant interval inside the panel, and a humidity sensor that detects the relative humidity inside the panel. A sensor is provided, and control means is provided to turn on the dehumidifier or electric heater when the detected value of the insulation resistance sensor is below a specified value or when the detected value of the humidity sensor is above the specified value.

<Function> According to the above configuration, even if the humidity is high, if the temperature is low and the insulation resistance is high, the dehumidifier or electric heater will not be operated, and the dehumidifier or electric heater will not be operated before dielectric breakdown of the insulator occurs. Able to operate an electric heater.

<Example> An embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a closed switchboard, and 2 an insulation resistance sensor, which, as described above, is constructed by arranging a pair of electrodes at regular intervals on a phenol resin plate, which is a type of insulator, for example.

3 is a humidity sensor, 4 is an electronically cooled dehumidifier or electric heater that utilizes the Peltier effect of semiconductors, and 5
is the control device.

Now, when the insulation resistance value of the insulator detected by the insulation resistance sensor 2 becomes, for example, 150MΩ or less, the control device 5 is activated and the dehumidifier or electric heater 4 is turned on, dehumidifying or heating the electric heater. Reduce internal humidity.

As a result, when the insulation resistance value recovers to 150 MΩ or more, the control device 5 is activated and the dehumidifier or electric heater 4 is turned off.

On the other hand, when the relative humidity detected by the humidity sensor 3 reaches, for example, 90% or more, the control device 5 operates and the dehumidifier or electric heater 4 is turned on to dehumidify or reduce the humidity inside the panel by generating heat from the electric heater. lower.

As a result, when the relative humidity inside the panel falls below 90%, the control device 5 is activated and the dehumidifier or electric heater 4 is turned off.

<Effects of the invention> As described above, according to this invention, an insulation resistance sensor and a humidity sensor are installed inside the panel, and the operation of the dehumidifier or electric heater is automatically controlled individually based on the detected values of both. Therefore, the detection standard value of the humidity sensor can be set relatively high, such as 90%, and the detection standard value of the insulation resistance sensor can also be set relatively low, such as 150MΩ. Insulation resistance often exceeds the specified value even when the temperature is low and the humidity is relatively high, below the specified value, but close to the specified value. In this case, there is no need to run the dehumidifier or electric heater, which results in wasted power. There is no consumption.

In addition, if the decrease in insulation resistance does not reach the specified value even if the relative humidity at low temperatures exceeds the specified value, dehumidification is performed based on the detected value of the humidity sensor, preventing dew condensation inside the panel due to sudden changes in weather. be able to.

Moreover, since a decrease in insulation of an insulator is detected by a decrease in insulation resistance, corona discharge on the surface of the insulator and, by extension, dielectric breakdown can be prevented.

Furthermore, in addition to being able to respond to sudden changes in the weather as mentioned above, the insulation resistance sensor can also detect long-term deterioration of electrical equipment due to dirt, etc., making maintenance management of electrical equipment easier.

[Brief explanation of the drawing]

The figure is a side view of a closed switchboard showing an embodiment of the present invention. 1... Closed switchboard, 2... Insulation resistance sensor, 3
... Humidity sensor, 4 ... Electronic cooling type dehumidifier or electric heater, 5 ... Control device.

Claims (1)

[Claims for Utility Model Registration] An insulation resistance sensor consisting of a pair of electrodes arranged at a certain interval on an insulating material, for detecting the insulation resistance of the insulating material, and for detecting relative humidity in a closed switchboard. a humidity sensor for the purpose of the present invention, and both sensors are provided in the closed switchboard, and when the detected value of the insulation resistance sensor is below a specified value, or when the detected value of the humidity sensor is above a specified value, a dehumidifier or an electric heating A dew condensation prevention device for a closed switchboard, consisting of a control means for turning the device on, and a device for preventing condensation on a closed switchboard.