JP2020028149A - Enclosed switchboard and method for preventing tracking in enclosed switchboard - Google Patents

Abstract

To prevent or suppress occurrence of a tracking phenomenon in an enclosed switchboard which is used for receiving and distributing high-voltage power in a metal smelting factory or a factory located near a coast.SOLUTION: An enclosed switchboard 1 includes an outer sheath 50 in which an inner device necessary to receive and distribute high-voltage power is housed, a ventilation opening 51 which is disposed at a position in the upper part of the outer sheath 50 so as to be downwardly open, and a closing member 2 which is disposed, in an attachable/detachable manner or in an openable/closable manner, in an opening section of the ventilation opening 51. Further, a management temperature for preventing tracking in the switchboard is set. When the temperature in the switchboard is lower than the management temperature for preventing tracking, the ventilation opening 51 is closed to prevent intrusion of dust from the outside into the switchboard so that a tracking phenomenon in the enclosed switchboard 1 is prevented. When the temperature in the switchboard is equal to or higher than the management temperature for preventing tracking, the ventilation opening 51 is opened to introduce outside air from the outside into the switchboard.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a closed switchboard, and more particularly, to a tracking prevention technique in a closed switchboard.

  2. Description of the Related Art In general, a closed type switchboard used for a power receiving and distribution facility having a high voltage or higher is installed on the premises of a factory or on the rooftop. This type of distribution panel includes a bus room for distributing electricity after receiving power into the panel, a cable room for connecting a cable for supplying power from the bus room to each device used, and a circuit breaker for interrupting and controlling current from the bus. It has a plurality of compartments having various functions such as a room and a control room, and these compartments are compactly stored in one outer shell. Here, the high voltage refers to a voltage exceeding 750 V for direct current and exceeding 600 V for alternating current.

  During operation of the closed switchboard, internal equipment generates heat. For this reason, ventilation holes are provided in appropriate places in the outer shell to achieve cooling by the flow of outside air. However, depending on the conditions of the installation place of the switchboard, dust may enter the outer shell from the ventilation opening. Further, when the outside air becomes humid depending on the season, humid air may flow in from the ventilation opening. Then, when humid air is added to the dust that has entered and accumulated in the panel, there is a high possibility that a tracking phenomenon occurs in the devices in the panel.

  Here, the tracking phenomenon means that when humidity is added to the dust accumulated on the surface of the insulator, the insulation resistance of the surface is reduced and a leakage occurs, and the spark discharge generated there causes the surface of the insulator made of resin such as epoxy. Is thermally decomposed and carbonized to form a conductive path. If a tracking phenomenon occurs in the internal equipment of a closed switchboard, the possibility of occurrence of a ground fault or short circuit increases (in the worst case, a serious problem such as a fire or explosion occurs). Such problems are more pronounced in metal smelting factories or coastal factories.

  Therefore, in order to prevent such a tracking phenomenon, a measure has been proposed in which dry air generated outside the switchboard is blown into the panel and air in the panel is replaced with dry air to perform dehumidification (for example, And Patent Document 1). In addition, a measure has been proposed in which a heater is installed inside a switchboard, and when the humidity in the panel increases, the heater is operated to increase the internal temperature and decrease the relative humidity in the panel (for example, see Patents). Reference 2).

JP-A-1990-202304 JP-A-1984-56804

According to the measures disclosed in Patent Literature 1 and Patent Literature 2, by preventing dew condensation inside the panel, it is possible to prevent the dust accumulated in the panel and the insulation resistance from being reduced due to the dew condensation and the occurrence of the tracking phenomenon due thereto.
However, according to the study of the present inventors, when the installation location of the closed switchboard is near the sea, lake, marsh, or river, especially in a factory located within 3 km from the coast, the increase and decrease due to the influence of the wind direction, etc. Despite this, some water adheres to the dust, and in strong winds, seawater droplets may adhere. In this way, if the dust itself is moist from the beginning or contains salt, the insulation resistance of the internal equipment surface will decrease even if there is no condensation from the moisture in the atmosphere, and the dust accumulated in the panel It has been found that the possibility of occurrence of the tracking phenomenon cannot be excluded.

Further, according to the study of the present inventors, a closed type switchboard installed in a place such as a metal smelting factory where a large amount of metal dust is present, the dust itself has conductivity, and in such a case, it is not necessarily required. It has been found that even under the condition where there is no condensation, there is a possibility that the tracking phenomenon may occur due to a decrease in the insulation resistance of the internal device surface.
Therefore, the present invention has been made in view of such a problem, and is used in a metal smelting factory or a factory located along the seashore for power receiving and distribution equipment at a high voltage or more. An object of the present invention is to provide a closed switchboard and a method for preventing tracking of the closed switchboard that can prevent or suppress the occurrence of a tracking phenomenon.

In order to solve the above problems, a closed switchboard according to one embodiment of the present invention is a closed switchboard used in a metal smelting factory or a factory located along the seashore, and is required for power reception and distribution at a high voltage or higher. An outer shell in which the internal device is housed, a ventilation port provided to open downward at the upper position of the outer shell, and a closing member detachably or closably disposed in the opening of the ventilation port. , Is characterized by having.
According to the closed type switchboard of one embodiment of the present invention, the shutoff member is provided at the opening of the ventilation port so as to be detachably or removably opened and closed, so that intrusion of dust into the panel can be minimized. Therefore, it is possible to prevent or suppress the occurrence of the tracking phenomenon due to the influence of the external environment of the closed switchboard.

  Further, in order to solve the above problem, a tracking prevention method for a closed switchboard according to one embodiment of the present invention is a tracking prevention method using the closed switchboard according to one embodiment of the present invention, wherein Using a thermometer to measure the temperature of, the tracking prevention management temperature is set in advance, the closing member is attached or detached or opened and closed based on the temperature indication value of the thermometer for the tracking prevention management temperature, the temperature indication value is When the temperature is equal to or higher than the tracking prevention management temperature, the ventilation opening is opened and outside air is introduced into the panel from the outside, and when the temperature instruction value is lower than the tracking prevention management temperature, the ventilation opening is closed and the outside is closed. It is characterized in that dust is prevented from entering the panel and the occurrence of tracking phenomenon in the closed switchboard is prevented.

  According to the tracking prevention method for a closed switchboard according to one embodiment of the present invention, the closing member can be appropriately opened and closed based on a temperature indication value of a thermometer with respect to a tracking prevention management temperature. Therefore, intrusion of dust into the panel can be suppressed to a minimum, and the occurrence of a tracking phenomenon due to the influence of the external environment of the closed switchboard can be prevented or suppressed.

  As described above, according to the present invention, it is possible to prevent or suppress the occurrence of a tracking phenomenon in a closed-type switchboard used in a power receiving and distribution facility having a high voltage or more in a metal smelting factory or a factory located along the coast.

It is the typical sectional view which looked at one embodiment of a closed distribution board concerning one mode of the present invention from the side. It is a principal part enlarged view explaining the ventilation opening with an opening / closing mechanism with which the closed switchboard of FIG. 1 is provided. 3 is a flowchart of a tracking prevention management process executed by a control unit included in the closed switchboard of FIG. 1. It is a principal part enlarged view explaining another example of the ventilation opening which can be provided in the closed switchboard of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. The closed switchboard according to the present embodiment is used for receiving and distributing power at a high voltage or higher, and is an example particularly used in a metal smelting factory or a factory located along the coast.
The drawings are schematic. Therefore, it should be noted that the relationship between the thickness and the planar dimension, the ratio, and the like are different from the actual ones, and the drawings include portions having different dimensional relationships and ratios. The embodiments described below exemplify an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention is based on the material, shape, structure, and arrangement of the component parts. Are not specified in the following embodiments.

  As shown in FIG. 1, the closed switchboard 1 of the present embodiment includes a metal outer shell 50 formed in a substantially rectangular parallelepiped box shape. Inside the outer shell 50, there are a bus room 40 into which a bus 41 for distributing electricity after receiving power into the panel, and a cable room 30 for connecting a cable 31 for supplying electric power from the bus room 40 to each used device. , A plurality of sections having various functions, such as a circuit breaker room 20 for interrupting the current from the bus 41 and a control room 10 for controlling the current from the bus 41, are provided. Is compactly housed in the outer shell 50 of the camera.

  The outer shell 50 is provided with four side wall surfaces 55 surrounding the periphery, a top plate surface 52 provided so as to cover an upper portion of the side wall surface 55, and a top plate surface 52 facing the top plate surface 52. From above, and a roof portion 53 covering the upper portion of the side wall surface 55 and the outside thereof. In addition, a punching metal is used for the inner partition wall where there is no problem in maintenance (the portion indicated by the two-dot chain line in the figure). On the left and right sides of the roof 53, an eaves portion 54 is formed which protrudes more laterally than the side wall surface 55, and a ventilation port 51 is provided at a position between the eaves portion 54 and the side wall surface 55 so as to open downward. Is provided.

Here, the inventors of the present invention have studied to minimize the intrusion of dust into the closed switchboard 1 for the purpose of eliminating the possibility of occurrence of the tracking phenomenon. Was closed, the temperature change in the closed switchboard 1 was closely examined. In the present embodiment, the usage status of a closed switchboard with a voltage of 22 kV and a permissible current of 3000 A, which is common in a metal smelting factory, was confirmed.
As a result, in the metal smelting factory, at 40 ° C., which is the maximum value of the outside air temperature around the closed switchboard 1 assumed in a standard use state, the current does not exceed 2340 A corresponding to 78% of the allowable current of the internal equipment. As far as possible, it has been found that the temperature inside the closed switchboard 1 does not exceed 55 ° C. which is the allowable use temperature of the internal equipment.

  Therefore, in the present embodiment, an openable and closable closing member 2 is installed in the opening of the ventilation port 51 of the closed-type switchboard 1, and the ventilation port 51 is closed under appropriate conditions by the closing member 2, so that the outside can be opened. Intrusion of dust from the outside of the shell 50 into the board is prevented, and the possibility of occurrence of a tracking phenomenon is eliminated. That is, in the present embodiment, the closed type switchboard 1 has been conceived as a result of careful and detailed examination of the use environment of the closed switchboard 1 in order to prevent leakage due to the tracking phenomenon due to the external environment.

Hereinafter, the opening and closing structure of the ventilation port 51 provided in the closed switchboard 1 according to the present embodiment will be described with reference to FIG.
In the closed switchboard 1 of the present embodiment, the internal device has a closed structure that can ventilate outside air only when the load is high. This prevents intrusion of dust from the outside of the outer shell 50 and secures air permeability in the panel as necessary, thereby preventing accidents such as leakage due to tracking phenomena due to the external environment such as dust. Contribute to. Moreover, the closed type switchboard 1 of this embodiment can reduce initial cost and operation cost by making the opening / closing structure of the ventilation port 51 simple.

In the present embodiment, the closing of the ventilation opening by the closing member 2 is performed by opening and closing the plate-shaped closing member 2 formed so that the opening can be closed by the drive motor 3 as shown in an enlarged view of a main part in FIG. . With such a configuration, it is possible to easily perform the closing management of the ventilation port 51.
Further, in this embodiment, a temperature sensor (thermometer) 5 is installed in the closed switchboard 1, and when the internal temperature reaches a predetermined tracking prevention management temperature, the drive motor 3 is controlled by the control unit 4. The closing member 2 can be opened and closed automatically by being controlled and driven.

The control unit 4 is configured to be able to execute the tracking prevention management process shown in the flowchart in FIG. The control unit 4 according to the present embodiment includes software for tracking prevention management processing, and a computer configured to execute the software.
The computer can acquire a temperature indication value (S ° C.) from the temperature sensor (thermometer) 5 via a signal line, and can drive the drive motor 3 via a signal line. Information of a preset tracking prevention management temperature (A ° C.) is stored in a storage device of the computer.

In the present embodiment, the tracking prevention control temperature (A ° C.) is 78 ° of the allowable current of the internal device at the maximum value of the outside air temperature around the panel when the internal device is assumed in the standard use state (for example, the above 40 ° C.). %, Which is set as long as the value does not exceed the value corresponding to% (for example, 55 ° C. = (A ° C.)).
When the tracking prevention management process is executed by the control unit 4, as shown in FIG. 3, the process first proceeds to step S1 to read the tracking prevention management temperature (A ° C.), and then proceeds to step S2 where the temperature sensor (thermometer) is read. ) Acquire the temperature indication value (S ° C) from 5. Next, in steps S3 to S5, the closing member 2 is opened and closed by controlling the driving motor 3 as a driving unit based on the temperature instruction value (S ° C.) of the temperature sensor 5 with respect to the tracking prevention management temperature (A ° C.). I do.

In other words, in the present embodiment, when the temperature instruction value (S ° C.) is equal to or higher than the tracking prevention management temperature (A ° C.) (Yes) in step S3, the control unit 4 proceeds to step S4 and closes the ventilation port 51. The closing member 2 is positioned at the open position so as to open and introduce outside air into the panel from the outside (release drive).
When the temperature instruction value (S ° C.) is lower than the tracking prevention management temperature (A ° C.) (No) in step S3, the control unit 4 proceeds to step S5, closes the ventilation port 51, and receives an external command. The closing member 2 is positioned at the closed position so as to prevent dust from entering the panel, thereby preventing the tracking phenomenon in the closed switchboard 1 (closing drive).

Next, the operation and effects of the closed switchboard 1 of the present embodiment will be described.
According to the closed switchboard 1, since the control unit 4 executes the above-described tracking prevention management processing for opening and closing the closing member 2, the intrusion of dust into the outer shell 50 of the closed switchboard 1 is prevented or significantly reduced. Can be reduced. Therefore, the possibility of electric leakage due to the tracking phenomenon can be extremely reduced.
It should be noted that the closed switchboard according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, an example has been described in which tracking prevention management is performed by automatic control. However, the present invention is not limited to this, and opening and closing management of the closing member may be performed by manual opening and closing by an operator.

  Specifically, as shown in an enlarged view of a main part of another example in FIG. 4, the closing member 2 </ b> B is a circular plate-shaped lid having an area covering the opening of the ventilation port 51. The closing member 2B is removably attached to the eaves portion 54 forming the ventilation port 51 by a worker with an appropriate attachment / detachment structure such as a fitting type by fitting a spigot, a screw type, or a magnetic attraction. By doing so, the opening of the ventilation port 51 can be easily closed by a manual opening / closing operation by an operator.

  Also in this other example, similarly to the above-described embodiment, the tracking prevention management temperature in the panel is set, and when the temperature in the panel is lower than the tracking prevention management temperature, the ventilation port 51 is operated by the operator's judgment. It is closed by a manual opening / closing operation by a user to prevent dust from entering the inside of the panel from the outside of the outer shell 50, thereby preventing the tracking phenomenon in the closed power distribution panel 1. Further, when the temperature in the panel is equal to or higher than the tracking prevention management temperature, the ventilation port 51 is opened by a manual opening / closing operation by an operator, so that outside air can be introduced into the panel from outside the outer shell 50.

Thereby, even when the outside air temperature rises or the power load used in the closed switchboard 1 increases, the closing member 2 can be closed by the manual opening / closing type closing structure such as the closing member 2B shown in FIG. By appropriately removing the temperature, the ambient temperature in the panel can be kept below the allowable operating temperature of the internal equipment.
In addition, even in a configuration such as this other example, when the outside air temperature is low or the power load used is small, the ventilation port 51 can be always closed. Therefore, intrusion of dust from the outside can be appropriately prevented, and the degree of accumulation of dust in the panel can be reduced. For this reason, the possibility of electric leakage due to the tracking phenomenon in the panel can be reduced.

  In addition, even in the above-described embodiment and other examples, when the power load used increases, there is an opportunity to open the ventilation port 51 and an opportunity to open the inspection door of the switchboard for equipment inspection. There is also a possibility that dust may enter the panel from outside the outer shell 50 at such a timing. Therefore, in addition to the configuration of the above-described embodiment or another example, it is also possible to use a dehumidifier for a switchboard or a fan heater for a switchboard, which is an existing technology.

  In this case, it is preferable to use a dehumidifier and / or a fan heater in the above-described embodiment or another example, and to always keep the humidity in the panel at 70% or less. As a device arrangement such as a dehumidifier or a fan heater, it is preferable to install a dehumidifier having a high humidity reducing effect in the cable room 30 and / or the control room 10 to effectively dehumidify the entire panel. Further, it is preferable to use a fan heater together with a dehumidifier for dehumidification in the panel. At this time, it is preferable to install a fan heater at a position where heat is easily diffused to the entire panel (for example, near the center of the outer shell 50).

1 Closed switchboard 2 Lid (closing member)
3 Drive motor (drive unit: open / close mechanism)
4 control part (opening and closing mechanism)
5 Temperature sensor (thermometer)
Reference Signs List 10 control room 11 internal equipment 20 breaker room 21 breaker 30 cable room 31 cable 40 busbar room 41 busbar (main circuit conductor)
Reference Signs List 50 outer shell 51 ventilation port 52 top plate 53 roof 54 eaves tip 55 side wall 60 insulating insulator S drive command

Claims (7)

A closed switchboard used in metal smelting factories or factories located along the coast,
An outer shell in which internal equipment necessary for receiving and distributing power at a high voltage or more is accommodated, a ventilation opening provided to open downward at an upper position of the outer shell, and detachable or openable / closable at an opening of the ventilation opening And a closing member disposed on the switchboard.   The closed switchboard according to claim 1, wherein the closing member is a lid that removably covers an opening of the ventilation port.   The thermometer for measuring the temperature in the outer shell, a drive unit for opening and closing the closing member, and a control unit for controlling the drive unit in accordance with a temperature instruction value of the thermometer. Closed switchboard. The control unit includes:
A tracking prevention management temperature is set, and a tracking prevention management process for controlling the drive unit based on a temperature indication value of the thermometer with respect to the tracking prevention management temperature to open and close the closing member is configured to be executable. Yes,
When the temperature instruction value is equal to or higher than the tracking prevention management temperature, the closing member is located at the open position so as to open the ventilation port and introduce outside air into the panel from the outside,
When the temperature instruction value is lower than the tracking prevention control temperature, the closed member is located at a closed position so as to close the ventilation port and prevent intrusion of dust from the outside into the panel, and the closed type switchboard. The closed switchboard according to claim 3, wherein a tracking phenomenon is prevented from occurring in the switchboard.   The tracking prevention management temperature is set as long as the internal device does not exceed a value corresponding to 78% of the allowable current of the internal device at the maximum value of the outside air temperature around the panel when the internal device is assumed in a standard use state. The closed switchboard according to claim 4, which is an allowable operating temperature of the internal device. A method for preventing tracking of a closed switchboard according to claim 1 or 2,
Using a thermometer to measure the temperature in the outer shell, the tracking prevention control temperature is set in advance,
Opening and closing or opening and closing the closing member based on the temperature indication value of the thermometer for the tracking prevention management temperature,
When the temperature instruction value is equal to or higher than the tracking prevention management temperature, open the ventilation port and introduce outside air into the panel from the outside,
When the temperature indication value is lower than the tracking prevention management temperature, the ventilation port is closed to prevent dust from entering the panel from the outside to prevent a tracking phenomenon from occurring in the closed switchboard. Characteristic tracking prevention method for closed switchboards.   The preset tracking prevention management temperature does not exceed a value corresponding to 78% of the allowable current of the internal device at the maximum value of the outside air temperature around the panel when the internal device is assumed in a standard use state. 7. The tracking prevention method for a closed switchboard according to claim 6, wherein the allowable operating temperature of the internal device is set as far as possible.

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