JPH03225808A - Snow-melting apparatus utilizing waste heat of oil-filled electrical equipment - Google Patents

Abstract

PURPOSE:To enable road surface snow melting at a low operating cost and with a high reliability by transmitting the waste heat of a transformer to a secondary fluid via heat exchanger and by releasing the heated secondary fluid to the road surface through a snow-melting secondary fluid-releasing means. CONSTITUTION:When a primary fluid pump 3 is operated, an insulating oil in the tank of an electrical equipment flows through the primary flow path of a heat exchanger 15 and the primary fluid pump 3. In this case, a valve 14 connected in series with a heat-dissipator 13 is closed so that the insulating oil does not flow through the heat-dissipator 13 and the cooling action of the insulating oil by the heat dissipator 13 stops. When a secondary fluid pump 4 is operated in a state where the primary fluid pump 3 is operated, heat exchange is conducted between primary fluid (insulating oil) and secondary fluid (e.g. water) and the temperature of the secondary fluid is raised as the insulating oil is cooled. Then, the secondary fluid is released from a snow- melting secondary fluid-releasing means 25 and snow melting is conducted in the case of snow. Thus, it is possible to continue operation at low maintenance costs and to contrive to maintain a high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a snow melting device that utilizes waste heat from oil-filled electrical equipment such as oil-filled transformers and oil-filled paddles.

[Conventional technology] In electrical facilities such as substations installed in snowy areas,
If there is snow on the roads within the facility, it will hinder the movement of personnel and inspection equipment during maintenance inspections and accident recovery work. Therefore, it is necessary to perform snow removal work, but it is troublesome to perform snow removal work every time a periodic inspection is performed. Particularly in the event of an emergency such as an accident, it is necessary to carry out recovery in the shortest possible time, but if snow removal is performed prior to recovery work, it will take a long time for recovery to occur, causing inconvenience. Therefore, in electrical facilities such as substations, it is preferable to keep roads cleared of snow at all times. Generally, methods for removing snow include manual methods and methods using snowplows, but these methods require a large number of workers, take a long time, and are inefficient. Especially these days, most of the substations are unmanned, so these snow removal methods cannot be adopted.

Therefore, in order to solve these problems, the installation of snow melting devices in electrical facilities such as substations to prevent snow from accumulating on the roads is being considered.

Snow melting devices are of the heating wire type, which heats the road surface and melts snow by burying a resistance heating wire under the road surface and energizing the resistance heating wire, and the other uses a heated fluid (usually a mixture of water and antifreeze). A fluid heating method that melts snow by burying a heat dissipating means for snow melting under the road surface and dissipating the heat of the fluid passing through the internal flow channel of the heat dissipating means into the ground. There are two types of snow-sprinkling systems that spray water onto the road to melt snow.

[Problem to be solved by the invention] Of the above methods, the most commonly adopted method for melting snow on roads is the heating wire method, but this method requires a considerable amount of electricity and is therefore not maintained. Expenses will increase. The benefits of snow melting are widespread on arterial roads with heavy vehicle traffic and on sidewalks with many passersby, so cost balance can be maintained even if the heating line method, which has high maintenance costs, is adopted, but substations In areas with extremely low traffic volume, such as hallways within the campus,
Snow melting methods are unsuitable because of their high maintenance costs.

In addition, conventional snow melting systems using fluid heating systems use boilers that use petroleum-based fuel to heat the fluid, which increases maintenance costs and makes them unsuitable for snow melting systems on roads with low traffic volume. there were.

Furthermore, normal sprinkler-type snow melting equipment consumes a large amount of water,
In cold regions, it is necessary to heat the water to a certain extent before spraying, which requires fuel for heating, which inevitably increases maintenance costs.

By the way, electrical facilities such as substations are equipped with oil-filled electrical equipment such as oil-filled transformers and oil-filled paddles, and these electrical equipment constantly generate heat.

In order to operate electrical equipment, it is necessary to dissipate the heat generated outside to maintain the temperature of the equipment below a predetermined value. Conventionally, waste heat from these equipment is dumped into the outside air through a radiator. However, in recent years, various proposals have been made for effectively utilizing this waste heat.

For example, Japanese Unexamined Patent Publication No. 60-62103 discloses a proposal to utilize waste heat from oil-filled electrical equipment for hot water supply equipment. Furthermore, Japanese Patent Laid-Open No. 59-80916 proposes a method of recovering waste heat from a transformer or the like via a heat pump and using it as a heat source for an absorption refrigerator. Furthermore, the monthly magazine OHM April 1989 issue published by Ohmsha in April 1989 (
VOL, 76/No. 4) +: C. It has been shown that waste heat from transformers and reactors can be used as hot water in the cooling system for air equipment in underground substations.

However, all of the previously proposed waste heat utilization from oil-filled electrical equipment requires that the hot water supply equipment, air conditioning area, etc. be located near the transformer, and its application is limited to transformers installed inside buildings in urban areas. . Therefore, conventionally proposed methods of utilizing waste heat from electrical equipment cannot be applied to electrical equipment in electrical facilities installed in unmanned substations and the like.

Furthermore, because oil-filled electrical equipment such as transformers must maintain high reliability over long periods of time, the upper limit of the allowable temperature rise of insulating oil is set at a relatively low temperature of around 55°C. There is. Therefore, even if waste heat from a transformer or the like is supplied to a water heater, hot water at a temperature that high cannot be obtained. Moreover, the temperature of electrical equipment is not constant, but fluctuates significantly as the load fluctuates, so equipment that needs to obtain a temperature within a certain range, such as water heaters and air conditioners, is a waste of oil-filled electrical equipment. It is not necessarily suitable as a device that utilizes heat.

The object of the present invention is to provide a snow melting device that utilizes the waste heat of oil-filled electrical equipment, which works ideally as a consumption source for effectively utilizing the waste heat of oil-filled electrical equipment, and which enables continued operation with low maintenance costs. It is about providing.

[Means for Solving the Problems] Appropriate as a device that utilizes waste heat from oil-filled electrical equipment is a device that has a relatively low operating temperature and is not affected by large temperature fluctuations. Snow melting equipment does not require very high temperatures and can tolerate large temperature fluctuations, making it an ideal source of waste heat consumption for oil-filled electrical equipment. Furthermore, when using waste heat from oil-filled electrical equipment, consideration must be given to not impairing the reliability of the electrical equipment.

The present invention focuses on these points and provides a snow melting device that utilizes waste heat from oil-filled electrical equipment. A heat exchanger having a secondary flow path for flowing heat exchange between both flow paths, and a primary fluid connected in series to the primary flow path and the secondary flow path of the heat exchanger, respectively. a pump and a secondary fluid pump, and a second fluid having an internal flow path for passing the secondary fluid and passing through the internal flow path.
The snow melting secondary fluid discharging means for dispersing the secondary fluid to the outside is provided.

Both ends of the series circuit between the primary flow path of the heat exchanger and the primary fluid pump are connected to the tank of the oil-filled electrical equipment equipped with a radiator, so that when the primary fluid pump is operated, the inside of the tank of the oil-filled electrical equipment is A primary fluid circulation system is configured to circulate insulating oil through the primary flow path of the heat exchanger.

The snow melting secondary fluid discharge means is connected to the secondary fluid pump via the secondary flow path of the heat exchanger, and the snow melting secondary fluid discharge means, the secondary flow path, and the secondary fluid pump discharge the secondary fluid. A release system is configured.

A valve that prevents backflow of insulating oil within the radiator is connected in series to the radiator of the oil-filled electrical equipment, and a series circuit between the primary flow path of the heat exchanger and the primary fluid pump is connected in series to the radiator of the oil-filled electrical equipment. connected in parallel to the series circuit of the valve and the valve.

As the valve connected to the radiator, it is preferable to use a check valve that automatically closes when the pressure on the inlet side becomes lower than the pressure on the outlet side.
The solenoid valve may be closed when the primary fluid pump is operated.

Water may be used as the secondary fluid.

When automatically controlling the above-mentioned primary fluid pump and secondary fluid pump, as shown in FIG. A snowfall detector 2 for detecting the presence or absence of snowfall, and a control device 5 for controlling the primary fluid pump 3 and the secondary fluid pump 4 using the oil temperature detected by these detectors and the presence or absence of snowfall as control conditions are provided.

The control device 5 includes a primary fluid pump control means 6 and a secondary fluid pump control means 7. Here, the primary fluid pump control means 6 operates the primary fluid pump when the oil temperature detected by the oil temperature detector 1 is lower than the allowable upper limit value (less than the set maximum temperature), and the oil temperature is lower than the maximum allowable value. The primary fluid pump is controlled to stop the primary fluid pump when the temperature exceeds the set maximum temperature.The secondary fluid pump control means 7 also controls the oil temperature when snowfall is detected by the snowfall detector. The secondary fluid pump is operated when the oil temperature is below the set maximum temperature, and the secondary fluid pump is stopped when the oil temperature exceeds the set maximum temperature.
The secondary fluid pump is controlled to stop operation of the secondary fluid pump.

[Function] In the above device, when the primary fluid pump is stopped, insulating oil circulates from the tank of the electrical equipment through the radiator and backflow prevention valve, and the heat of the insulating oil is dissipated through the radiator. be done. This is no different from the normal operating condition of electrical equipment.

When the primary fluid pump is operated, the insulating oil in the tank of the electrical equipment flows through the primary flow path of the heat exchanger and the primary fluid pump. At this time, the valve connected in series to the radiator is closed, so the insulating oil does not flow inside the radiator, and the cooling effect of the insulating oil by the radiator stops. When the secondary fluid pump is operated while the primary fluid pump is operating, heat exchange occurs between the primary fluid (insulating oil) and the secondary fluid (for example, water), causing the insulating oil to cool. At the same time, the temperature of the secondary fluid is increased. The secondary fluid is discharged from the snow melting secondary fluid discharge means, and if there is snow, snow melting is performed.

Since the secondary fluid is heated by the waste heat of the electrical equipment and then released, snow melting is performed quickly and the consumption of the secondary fluid is also small. Furthermore, in cold conditions, it is possible to eliminate the risk of the discharged secondary fluid freezing.

When the primary fluid pump is operating and the secondary fluid pump is stopped, there is almost no heat exchange between the primary fluid and the secondary fluid, and at this time, the insulating oil is not cooled by the radiator. Therefore, the insulating oil is hardly cooled and circulates through a circulation system consisting of an electrical equipment tank, a heat exchanger, and a primary fluid pump. In this state, heat storage in oil operation occurs, and the heat generated from the electrical equipment body is stored in the insulating oil. When the temperature of the insulating oil is low, performing this kind of thermal storage operation in oil in preparation for snow melting will raise the temperature of the insulating oil and store thermal energy for snow melting in case it snows. be able to. In this case, it is natural that it is necessary to prevent the temperature of the insulating oil from exceeding the allowable upper limit temperature of the electrical equipment. In fact, it is preferable to perform this heat storage operation only during the snowy season and when the temperature of the insulating oil of the electrical equipment is below a set temperature that is considerably lower than the allowable upper limit temperature.

In addition, if a control device is installed that controls the primary fluid pump and secondary fluid pump using two control conditions: oil temperature and the presence or absence of snow, each of the above operations will be automatically selected depending on the situation at that time. can do.

That is, when there is snowfall, both the primary fluid pump and the secondary fluid pump are operated to melt the snow, and when there is no snowfall, the primary fluid pump is operated or stopped depending on the oil temperature. When there is no snowfall and the oil temperature is lower than the set maximum temperature, only the primary fluid pump is operated, and an in-oil heat storage operation is performed in which heat is stored in the insulating oil in the electrical equipment tank. Furthermore, regardless of whether or not there is snowfall, when the oil temperature exceeds the set maximum temperature, both the primary fluid pump and the secondary fluid pump are stopped, and the electrical equipment is operated normally. In this way, if you switch to cooling using a reliable radiator when the oil temperature exceeds the set maximum temperature and operate the electrical equipment, the oil temperature can be reliably lowered. The reliability of the equipment will not be compromised in any way.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

The electrical equipment used as a heat source in the present invention may be any oil-filled electrical equipment such as an oil-filled transformer or an oil-filled paddle, but in the following description, it is assumed that the electrical equipment used as a heat source is a transformer.

FIG. 1 schematically shows an embodiment of the present invention, in which reference numeral 10 denotes a transformer tank containing a transformer main body (not shown). A sending oil guide pipe 11 and a return oil guiding pipe 12 are drawn out from the upper and lower parts of the transformer tank 10, respectively, and one end of a radiator 13 is connected to the sending oil guide pipe 11. The other end of the radiator 13 is connected to the return oil pipe 12 via a check valve 14 . In this example, tank 10 → delivery oil pipe 11 → radiator 13 → check valve 14 → return oil pipe 12
→The path of the tank 10 constitutes a radiator circulation system. Circulation of the insulating oil in this system is performed by natural convection of the insulating oil caused by the temperature difference between the upper and lower sides of the radiator 13.

15 is a heat exchanger having a primary flow path 15a and a secondary flow path 15b, and one end of the primary flow path 15a of this heat exchanger is connected to the pipe 1.
6 and is connected to the delivery oil guide pipe 11 through the primary flow path 15a.
The other end is connected to the inlet side of the primary fluid pump 3 through a pipe 17. The outlet side of the primary fluid pump 3 is the piping 19
It is connected to the return oil pipe 12 through. In this example, tank 10 → oil delivery pipe 11 → piping 16 → heat exchanger 15
The primary flow path 15a → piping 17 → primary fluid pump 3 → piping 19 → return oil pipe 12 → tank 10 constitutes a primary fluid circulation system using insulating oil as the primary fluid. The circulation of the insulating oil in this circulation system is forced circulation by the pump 3.

The check valve 14 is a swing-type check valve that opens and closes based on the relationship between gravity and back pressure acting on a valve body (not shown), and normally opens due to the force of gravity acting on the valve body to release heat from the tank 10. An oil flow is generated in the radiator circulation system returning into the tank 10 through the vessel 13 and the check valve 14. When the primary fluid pump 3 is operated, the check valve 14 closes due to back pressure acting on the valve body of the check valve 14 (pressure acting from the bottom to the top of the check valve in FIG. 1), and the Create an oil flow through the fluid circulation system. At this time, tank 10 → delivery oil guide pipe 11 → radiator 1
3-No oil flow occurs in the radiator circulation system of check valve 14→return oil pipe 12→tank 10.

As described above, in the device according to the present invention, when oil flow is occurring in the primary fluid circulation system, the oil flow in the radiator circulation system is blocked, and when no oil flow is occurring in the primary fluid circulation system, the heat radiation is interrupted. Oil flow is occurring in the vessel circulation system.

Furthermore, when an oil flow is generated in the radiator circulation system, the primary fluid circulation system is not closed by a valve or the like, so a slight oil flow will occur through this primary fluid circulation system.
This oil flow is minute compared to the oil flow in the radiator circulation system.

The discharge side of the secondary fluid pump 4 is connected to one end of the secondary flow path 15b, and the piping 22 is connected to the suction side of the pump. This piping 22 is connected to a secondary fluid source (not shown).

A piping 23 is connected to the other end of the secondary flow path 15b, and a secondary fluid discharge means 25 consisting of a number of dispersion pipes 24 branched from this piping 23 is used to discharge the secondary fluid to the road surface that requires snow melting.
For example, it is designed to be washed onto the road surface inside a substation.

The secondary fluid discharge means 25 may be a known means used for road snow melting (for example, a means for discharging a secondary fluid from a number of water sprinkling holes laid on the road surface).

As the secondary fluid, it is preferable to use ground water in terms of snow melting effect and operating cost, but tap water may also be used.

When the secondary fluid pump 4 is operated, the secondary fluid flows through the piping 22 →
The fluid flows through the following route: secondary fluid pump 4 → secondary flow path 15b of heat exchanger 15 → piping 23 → dispersion pipe 24 (secondary fluid discharge means 25).

As described above, the secondary fluid flow path is an open flow system.

Operational control for accumulating or releasing waste heat from the transformer is performed by a control device 5.

This control device uses the temperature of insulating oil (oil temperature) detected by an oil temperature detector 1 attached to a tank 10 and the presence or absence of snowfall detected by a snowfall detector 2 as control conditions.
The primary fluid pump 3 and the secondary fluid pump 4 are controlled. The oil temperature detector 1 provides a signal to the control device 5, the details of which will be described later.

The snowfall detector 2 has a plurality of electrodes on an insulating plate surface that receives snowfall (or precipitation), and changes in the resistance value between the plurality of electrodes (when moisture adheres to the plate surface, there is a bridge between the electrodes due to moisture). The circuit has a circuit that detects moisture adhering to the board surface, and a circuit that detects the temperature at that time. This is a well-known device that determines that it is snowing when moisture is detected at a temperature (normally set at 1°C to 3°C), and this snowfall detector 2 continues to output a signal until the snowfall stops. is sent to the control device 5.

A control device 5 receives a signal from an oil temperature detector 1 and a snowfall detector 2.
The primary fluid pump 3 and the secondary fluid pump 4 are automatically operated and stopped based on signals from the controller.

The control device 5 has a function of switching the operation mode to manual operation, automatic operation using a time switch, etc. in addition to performing the above-mentioned automatic operation, the details of which will be described later.

5 and 6 are flowcharts showing the control algorithm of the control device 5, FIG. 5 shows the operation modes that can be selected by the selection switch provided in the control device, and FIG. 6 shows the automatic operation mode by the selection switch. The control algorithm when is selected is shown.

First, referring to FIG. 5, "manual", "automatic", and "warm season" each indicate the switching position of a selection switch consisting of a three-point changeover switch. Here, "manual" indicates the position to be switched to when performing manual operation, and "automatic" indicates the position to be switched to when performing automatic operation with oil temperature and presence of snowfall as control conditions at the end of the stage.

In addition, "warm season" indicates a position to be switched when automatic operation by a timer is performed during a period other than the final season. In the latter stages of the year, it is reasonable to make assumptions based on the average values for the first and last snowfall in the area where the transformer is installed, allowing for a reasonable margin.

The operation switch SWI shown in FIG. 5 is a manual operation switch for the primary fluid pump 3, and by manually closing this switch, the primary fluid pump can be operated. Further, the operation switch SW2 is a switch for manually operating the secondary fluid pump 4, and the secondary fluid pump 4 can be operated by closing this switch SW2.

The time switch is used to operate the secondary fluid pump for a short time every predetermined period (for example, one week).
The secondary fluid pump 4 is closed for a certain period of time every predetermined period.
issues a command to operate for a certain period of time.

During the warm season when there is no snowfall, the selection switch is switched to "warm season". In this case, the secondary fluid pump 4 is operated every time the time switch is closed, and when the time switch is opened (and the secondary fluid pump is stopped), the time switch is closed for a fixed period of time, for example, every week. Since the rotating parts of the secondary fluid pump are in contact with water, if they are stopped for a long period of time, they may rust and cause problems in rotation.

Furthermore, if the secondary fluid discharge system is stopped for a long period of time, limescale may accumulate in the secondary flow path of the heat exchanger 15 and its performance may deteriorate. By operating the secondary fluid pump at regular intervals using the time switch as described above, these disadvantages can be prevented from occurring.

Further, in a state where the selection switch is switched to "warm season", the secondary fluid pump can be operated as desired by operating the operation switch SW2. That is, the secondary fluid pump 4 can be operated by closing the operation switch SW2, and the pump 4 can be stopped by opening the switch SW2.

Since the primary fluid pump 3 is submerged in oil and there is no risk of rust, the operating switch SW1 for manually operating the primary fluid pump is kept open during the warm season.

Next, the operation when the selection switch is changed to "1 manual" will be explained. This "manual" position is a position selected when the primary fluid pump and the secondary fluid pump are manually operated by human judgment. For example, at the end of the stage, if the automatic operation described below is selected, the primary fluid pump 3 and the secondary fluid pump 4 will be automatically operated using the oil temperature and the presence or absence of snow as control conditions, but depending on the situation, the pumps 3 and 4 may be operated automatically. This "manual" mode is selected when you want to continue driving, for example when there is no snowfall but there is a risk of the road freezing.

When the "manual" mode is selected by the selection switch, the primary fluid pump 3 can be operated by closing the operation switch SWI, and the secondary fluid pump 4 can be operated by closing the operation switch SW2. I can do it.

Next, when the "automatic operation" mode is selected by the selection switch, automatic operation is performed using the oil temperature and the presence or absence of snow as control conditions. In this automatic operation, a sequencer is used to realize the primary fluid pump control means and the secondary fluid pump control means by a program created according to the control algorithm shown in FIG.

In this automatic operation mode, the following in-oil heat storage operation and
Snow melting operation is performed automatically.

(A) Heat storage operation in oil This is an operation for storing heat in the transformer tank in preparation for snowfall when there is no snowfall. In this operating state, the primary fluid pump 3 is operated and the secondary fluid pump 4 is stopped.

At this time, the check valve 14 closes to stop the oil flow within the radiator 13, so that heat is not radiated through the radiator 13.

Also, since the secondary fluid discharge system is also stopped, heat exchanger 15
Almost no heat exchange takes place. Therefore, much of the waste heat is accumulated within the transformer tank 10, causing the oil temperature to rise. At this time, since the insulating oil is circulated through the primary fluid circulation system by operating the primary fluid pump, the temperature distribution within the tank 10 becomes uniform and the temperature distribution is not biased.

(B) Snow Melting Operation In this operation performed during snowfall, both the primary fluid pump 3 and the secondary fluid pump 4 are operated. In this case as well, the heat exchanger 15
Heat exchange is performed between the insulating oil and the secondary fluid to raise the temperature of the secondary fluid, and the secondary fluid is discharged onto the road surface through the secondary fluid discharge means 25 to melt snow on the road surface.

Since the secondary fluid is heated by the waste heat of the electrical equipment and then released, snow melting is performed quickly and the consumption of the secondary fluid is also small. Further, it is possible to eliminate the possibility that the secondary fluid released in a cold state may freeze.

Next, details of the operation in the automatic operation mode will be explained with reference to the flowchart in FIG.

In this automatic operation, the signal from the oil temperature detector 1 and the signal from the snowfall detector 2 are used as control signals.

The oil temperature detector 1 generates a signal T that shows a change with hysteresis as shown in FIG. 7 with respect to a change in the oil temperature θ.

In Fig. 7, θ2 is the set maximum temperature that is the criterion for stopping the operation of the primary fluid pump and secondary fluid pump in the initial state and in the process of increasing oil temperature, and in the initial state and in the process of increasing oil temperature. When the oil temperature is less than this set maximum temperature 62, the primary fluid pump and secondary fluid pump are allowed to operate, and when the oil temperature reaches the set maximum temperature 02 or higher, the primary fluid pump and secondary fluid pump are allowed to operate. The pump shall be stopped.

Here, θ2 is set lower than the upper limit of the allowable temperature of the insulating oil in the transformer. The allowable temperature rise value of insulating oil is 5
When the temperature is 5°C, θ2 is set to, for example, the daily average temperature at the end of the season + 50°C. Also, θ1 is θ2-5
Set to about ℃.

In the initial state, the signal T generated by the oil temperature detector 1 goes to a high level when the oil temperature is 62 or higher, and as the oil temperature increases, it changes from a low level to a high level when the oil temperature reaches 62 or higher. become the level. Further, in the process in which the oil temperature decreases from a high level state, the signal T changes from a high level to a low level when the oil temperature becomes less than 01. In FIGS. 6 and 7, the state where the signal T is at a high level is set as T=1, and the state where the signal T is at a low level is set as T=O.

When the selection switch is switched to automatic operation and automatic operation is started, an operation command is issued to the primary fluid pump 3 in step P1 of FIG. 6, and the pump 3 is operated. Then, in step P2, the state of signal T is determined. When the oil temperature is less than the set maximum temperature 62, the signal T is at a low level.

Subsequently, in step P3, it is determined whether the snowfall detector detects snowfall. When snowfall is detected by the snowfall detector 2, an operation command is given to the secondary fluid pump 4 in step P4, and the secondary fluid pump 4 is operated. After performing step P4, the process returns to step P2 in which the state of the signal T is determined.

When it is determined in step P3 that snowfall has not been detected, a stop command is given to the secondary fluid pump 4 in step P5, and the operation of the pump is stopped. This state is heat storage operation in oil, and heat is stored within the transformer. After performing step P5, the process returns to step P2 in which the state of the signal T is determined.

When the signal T is at a high level in step P2, (θ
≧θ2), a stop command is issued to the primary fluid pump 3 and the secondary fluid pump 4 in step P6, and the operation of these pumps is stopped.

In this state, an oil flow is generated through the radiator 13 and steady operation is performed, and the insulating oil is cooled by the radiator 13.

In step P7, the state of the signal T is determined, and if the oil temperature is 01 or higher, the process returns to step P6 and the primary fluid pump and secondary fluid pump are held in a stopped state. When the oil temperature becomes less than 01 due to heat radiation by the radiator 13, the process returns to step P1 and the primary fluid pump 3
An operation command is issued to restart the operation of the pump 3.

Note that the flowchart showing the control algorithm for automatic driving is not limited to the one shown in FIG. 6, and various modifications are possible.

For example, a delay means may be incorporated between step P3 and step P5 in FIG. 6 to stop the secondary fluid pump after a certain delay time has elapsed after snowfall is no longer detected in step P3. good.

If the snowfall rate (the amount of snowfall per hour) is high, the snow will not melt immediately and there is a possibility that residual snow will remain on the road surface even after the snowfall has stopped. Therefore, in order to ensure complete snow melting, it is preferable to continue the snow melting operation for a predetermined period of time even after snowfall is no longer detected, as in the above modification.

Although it is not shown in the flowchart of Fig. 6, if there is an abnormality in the device while it is being operated in an operation mode other than normal operation, it will automatically switch to steady operation mode (primary fluid pump 3 and The secondary fluid pump 4 is stopped and the radiator 1
3), and is fixed to the steady operation mode. In this case, equipment abnormalities include, for example, cutoff of control power, excessive rise in oil temperature, stoppage of oil flow under a primary fluid pump operation command, stoppage of secondary fluid flow under a secondary fluid pump operation command, heat exchanger 1
Water leakage etc. at 5.

Although the above description has been made regarding the case where the radiator that cools the insulating oil during steady operation is a self-cooling type, the present invention is not limited to this. For example, as shown in FIG. 2, a forced air cooling type radiator equipped with a blower fan 30 is used, or as shown in FIG. 3, an oil feeding self-cooling type radiator equipped with an oil feeding pump 31 is used. You can also. Also the third
The present invention can also be applied to the case where an oil blowing air cooling type radiator is used, in which the radiator shown in the figure is further provided with a blower fan.

When using a radiator equipped with an oil pump 31 as shown in FIG. 3, it is necessary to prevent insulating oil from flowing toward the heat exchanger 15 when the pump 31 is operating. It is necessary to insert a valve 32 for preventing backflow into the system including the fluid pump 15 and the primary fluid pump 3.

3rd FI! In the example shown in J, a backflow prevention valve 14' provided in series with the radiator 13 and a valve 32 provided in the system on the heat exchanger 15 and primary fluid pump 3 side are controlled to open and close by electrical signals. A solenoid valve is used. When using a solenoid valve in this way, a step for controlling the solenoid valve is added to the flow showing the control algorithm for automatic operation.

Of course, check valves may be used as the valves 14' and 32 in FIG.

In addition, when using electromagnetic valves as the valve 14' and the valve 32, one pump is installed in the piping 12, serving both as the oil pump 31 for normal operation of the radiator and as the primary fluid pump 3. It's okay.

[Effects of the Invention] As described above, according to the present invention, the waste heat of the transformer is transferred to the secondary fluid through the heat exchanger without using fuel or combustion equipment for snow melting, and the heated secondary fluid is heated. Since the snow melting secondary fluid is discharged onto the road surface by the snow melting secondary fluid discharge means, road surface snow melting can be performed at low operating costs and with high reliability.

Since the secondary fluid is heated by the waste heat of the electrical equipment and then released, snow melting can be performed quickly and the amount of secondary fluid consumed can be reduced. Furthermore, in cold conditions, it is possible to eliminate the risk of the discharged secondary fluid freezing.

Further, according to the invention set forth in claim 5, not only can the pump be operated automatically, but also heat storage operation in oil can be performed to store heat in electrical equipment in preparation for snow melting, so the load factor of the transformer can be increased. Even when the amount of waste heat is small and the amount of waste heat is small,
It has the advantage of being able to melt snow quickly and reliably.

Furthermore, when the oil temperature exceeds the set maximum temperature, the operation of the pump is stopped and the radiator is operated steadily, so that the waste heat can be effectively used without any loss in reliability of the oil-filled electrical equipment.

[Brief explanation of drawings]

1 to 3 are schematic configuration diagrams showing different configuration examples of the snow melting device of the present invention, and FIG. 4 is a block diagram showing a configuration example of a control device used in the snow melting device according to the present invention,
FIG. 5 is a flowchart showing the operation modes that can be selected by the control device in FIG. 4, FIG. 6 is a flowchart showing the control algorithm when the automatic operation mode is selected by the control device, and FIG. FIG. 3 is a diagram for explaining signals obtained from an oil temperature detector used in Examples. 1...Oil temperature detector, 2...Snowfall detector, 3...1
Secondary fluid pump, 4... Secondary fluid pump, 5... Control device, 3... Heat radiator, 4... Check valve, 15... Heat exchanger, 25... Snow melting 2 Next fluid discharge means. Figure Figure Figure

Claims (5)

[Claims] (1) A heat exchanger that has a primary flow path through which a primary fluid flows and a secondary flow path through which a secondary fluid flows, and performs heat exchange between the two flow paths, and the primary flow path and the secondary flow path. A snow melting device having a primary fluid pump and a secondary fluid pump each connected in series with the channel, and an internal channel for passing the secondary fluid, and dissipating the secondary fluid passing through the internal channel to the outside. a secondary fluid discharge means, wherein both ends of a series circuit of the primary flow path of the heat exchanger and the primary fluid pump are connected to a tank of an oil-filled electrical device equipped with a radiator, A primary fluid circulation system is configured to circulate insulating oil in the tank through the primary flow path of the heat exchanger when the secondary fluid pump is in operation, and the secondary fluid discharge means for snow melting is configured to circulate the insulating oil in the tank through the primary flow path of the heat exchanger. It is connected to the secondary fluid pump via a flow path, and the snow melting heat radiation means, the secondary flow path, and the secondary fluid pump constitute a secondary fluid discharge system, and the insulating oil in the radiator is connected to the secondary fluid pump. A valve for preventing backflow is connected in series with the radiator, and a series circuit of the primary flow path of the heat exchanger and the primary fluid pump is connected in parallel with the series circuit of the radiator and the valve. A snow melting device using waste heat from oil-filled electrical equipment, characterized in that the equipment is connected to a (2) The snow melting device using waste heat from oil-filled electrical equipment according to claim 1, wherein the valve is a check valve that automatically closes when the pressure on the inlet side becomes lower than the pressure on the outlet side. (3) The snow melting device using waste heat from oil-filled electrical equipment according to claim 1, wherein the valve is a solenoid valve that is closed when the primary fluid pump is operated. (4) The snow melting device using waste heat from an oil-filled electrical equipment according to any one of claims 1 to 3, wherein the secondary fluid is water. (5) an oil temperature detector that detects the oil temperature in the tank of the oil-filled electrical equipment, a snowfall detector that detects the presence or absence of snowfall, and the primary fluid pump using the oil temperature and the presence or absence of snowfall as control conditions. and a control device that controls a secondary fluid pump, the control device operating the primary fluid pump when the oil temperature is lower than a set maximum temperature that is set lower than an allowable upper limit value, and 1. Controlling the primary fluid pump so as to stop the primary fluid pump when the temperature exceeds the set maximum temperature.
a secondary fluid pump control means, operating the secondary fluid pump when the oil temperature is less than the set maximum temperature while snowfall is detected by the snowfall detector, so that the oil temperature is equal to or higher than the set maximum temperature; secondary fluid pump control means for controlling the secondary fluid pump to stop the secondary fluid pump when the snowfall is detected, and to stop the operation of the secondary fluid pump when snowfall is not detected. The snow melting device using waste heat from oil-filled electrical equipment according to any one of claims 1 to 4.