JPH0350219B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dew condensation prevention device that includes a dew condensation dummy that generates condensation before an insulator or the like installed in a switchboard, detects the condensation, and issues an operation command for a dehumidifier. be.

For example, various electrical devices are housed inside a switchboard, and insulators such as insulators are installed to insulate the electrical devices.When the switchboard is energized, the temperature of the air inside the panel increases as the outside temperature increases. Rise.
At this time, if a temperature difference occurs between the electrical equipment or insulating material and the temperature inside the panel, dew condensation will occur on the surface of the electrical equipment or insulating material. In particular, dew condensation occurs on insulators such as insulators earlier than on electrical equipment whose temperature increases when energized. When dew condensation occurs on insulators or electrical equipment in this way, it is undesirable because it may cause insulation breakdown or rust. For this reason, in the past, a dew condensation dummy that condensed earlier than these insulating materials and electrical equipment was installed inside the panel, and a dehumidifier was linked to this dew condensation dummy via a dew sensor to prevent dew condensation on insulating materials and electrical equipment. Prevents condensation on the object. This dew condensation dummy has a higher heat capacity (=specific heat x mass) than the object to be prevented from condensation.
It is required that the temperature rise is large and the temperature rise is low, and that the thermal conductivity is high so that not only the surface but also the inside is heated evenly.

In order to satisfy the above requirements, the present inventors have developed a dew condensation dummy (Utility Model Application No. 55 - 80045), but the conventional ones including this one only have a heat capacity slightly larger than the object to be prevented from condensation, and if the object to be prevented from condensation changes, the condensation prevention function will change if the heat capacity differs. I will not be able to fulfill my goals.

The present invention has been made in view of the above points, and by using a Peltier element as a dew condensation dummy whose cooling temperature can be freely adjusted depending on the amount of current applied, it can easily be applied to various objects to be prevented from dew condensation. The purpose is to provide a dew condensation prevention device.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

1 to 5 show an embodiment of the present invention, in which 1 is a switchboard case, 2 is an electric device housed in the case 1, 3 is a dew condensation detector, and the atmosphere around the electric device 2 is It is installed inside. Reference numeral 4 denotes a dehumidifier which is activated upon receiving an operation command signal from the dew condensation detector 3 to dehumidify and prevent dew condensation on the electrical equipment 2 . In addition, electrical equipment 2 as an object to be prevented from condensation
Although they are shown together to simplify the explanation, they are distributed at predetermined locations within the case 1, and include insulators such as insulators.

The dew condensation detector 3 is composed of a Peltier element 10 as a dew condensation dummy, a dew condensation sensor 20, and an amplification/control section (not shown), and the Peltier element 10 has a structure as shown in FIG. It's summery. That is, a thermally conductive ceramic layer 12 and a conductive layer 13 are sequentially formed on one surface of a thermally conductive material (metal) 11 serving as a heat dissipating surface, while a thermally conductive layer 12 and a conductive layer 13 are sequentially formed on one surface of a thermally conductive material (metal) 14 serving as a heat absorbing (cooling) surface. A thermally conductive ceramic layer 15 is formed, and a pair of electrode parts 16, 1 are formed thereon.
7 are arranged in parallel, and a p-type semiconductor 18 is interposed between one electrode section 16 and the conductive layer 13, and an N-type semiconductor 19 is interposed between the other electrode section 17 and the conductive layer 13. ing. This Peltier element 10 has a cooling characteristic as shown in FIG _. As shown by l ₂ and l _3, the smaller the amount of current applied, the more constant the cooling temperature Δθ is regardless of the ambient temperature. The present invention takes advantage of the feature that the cooling temperature is approximately constant regardless of the ambient temperature, and adjusts the amount of current within that range to obtain the desired cooling temperature, thereby preventing dew condensation around the object. Create the required temperature difference with respect to the atmosphere.

On the other hand, as shown in FIG. 4, the dew condensation sensor 20 has a pair of lead wires 22 and 23 arranged at a constant distance on the surface of an alumina substrate 21, which is a good thermal conductor, and conductive powder is dispersed thereon. The film 24 is formed to a required thickness, and the Peltier element 1
0, and when dew condensation occurs on that surface, dew condensation is detected from the resistance change between the lead wires 22 and 23 due to the absorption of the water droplets.
The lead wires 22 and 23 are connected to an amplifier (not shown).

Note that if the Peltier element 10 as a dew condensation dummy is installed so that the heat dissipation surface 11 faces upward and the heat absorption surface 14 faces downward, convection will be promoted and the air flow on the heat absorption surface will be smooth, resulting in a faster response for detecting dew condensation. Become.

Next, the occurrence of dew condensation on the Peltier element 10 as a dew condensation dummy in the dew condensation detector having the above configuration will be explained with reference to FIG. 5, while comparing it with the case of an insulator which is most likely to condense in the panel. First, Peltier element 1
When 0.5A is applied to 0, the cooling temperature Δθ at that time is -2.5℃, although it is not shown in the characteristic diagram of Figure 3.
becomes. In addition, while maintaining the inside of the panel at 23℃,
Adjust the humidity inside the panel to approximately 90%. After maintaining this state for 30 minutes, when the dry bulb temperature inside the board (curve n ₁ ) is increased at a rate of approximately 4°C/hour, the temperature of the insulator (curve
n ₂ ) begins to rise slowly and later than the temperature inside the panel. At this time, the humidity gradually begins to decrease, but due to the uneven distribution due to natural convection, the dew point remains constant and does not change, so the wet bulb temperature becomes like curve n ₃ . Therefore, up to a certain point, the dew point changes as shown by the curve n ₄ , which approximates the curve n ₁ of the temperature inside the panel. Further, the temperature of the dew condensation surface of the dew condensation sensor 20 (curve n ₅ ) is adjusted to be 2.5 degrees Celsius lower than the temperature inside the panel, and increases while maintaining the temperature difference of 2.5 degrees Celsius. Condensation occurs at a point p ₁ where the temperature curve n ₅ of the dew condensation surface and the dew point curve n ₄ intersect. on the other hand,
Condensation occurs on the insulator surface at the intersection point p ₂ of curves n ₂ and n ₄ .
However, in reality, dew condensation on the Peltier element 10 serving as a dew condensation dummy is detected by the dew condensation sensor 20 and the operation of the dehumidifier 4 is started, and dew condensation does not occur on the insulator, which is the object to be prevented from dew condensation.

In the above explanation, the cooling surface of the Peltier element 10 used as a dew condensation dummy was adjusted to 2.5 degrees Celsius lower than the ambient temperature. By setting the settings appropriately according to the object, it can be applied to various objects to be prevented from dew condensation.

As described above, according to the present invention, a Peltier element whose cooling temperature can be freely adjusted according to the amount of electricity is used as a condensation dummy, a dew condensation sensor is attached to this condensation dummy, and a dehumidifier is operated by the output of this sensor. This makes it easy to dehumidify objects to be prevented from condensation.

Furthermore, if the dew condensation dummy as a Peltier element is installed with its heat absorption surface facing downward, convection is promoted, resulting in faster dew condensation detection response and faster prevention of dehumidification.

[Brief explanation of drawings]

The drawings show an embodiment of the dew condensation prevention device according to the present invention, and FIG. 1 is a schematic diagram showing the arrangement of the dew condensation prevention device, FIG. 2 is an explanatory diagram of the configuration of a Peltier element used as a dew condensation dummy, and FIG. is a cooling characteristic diagram of the same Peltier element, FIG. 4 is a plan view of a dew condensation sensor, and FIG. 5 is a characteristic diagram showing the occurrence of dew condensation on a dew condensation dummy and an insulator. 1...Switchboard case, 2...Electrical equipment, 3...
Dew condensation detector, 4... Dehumidification device, 10... Dew condensation dummy (Peltier element), 11... Heat radiation surface, 12 and 15... Heat conductive ceramic layer, 13... Conductive layer, 14... Heat absorption surface, 16 and 17... electrode part,
18...P-type semiconductor, 19...N-type semiconductor, 20
...Condensation sensor.

Claims (1)

[Scope of Claims] 1. A Peltier element disposed in a switchboard and operated within a range where the cooling temperature is substantially constant regardless of the ambient temperature inside the panel, and a dew condensation element attached to the heat absorption surface of the Peltier element. A dew condensation prevention device comprising a sensor and a dehumidifier that is activated when the sensor sends an output and dehumidifies an object to be prevented from dew condensation disposed in a power distribution board. 2. The dew condensation prevention device according to claim 1, wherein the Peltier element is installed in the atmosphere around the object to be prevented from dew condensation so that its heat absorption surface faces downward.