JPH01239906A - Gas insulated transformer - Google Patents

Abstract

PURPOSE:To improve the cooling characteristics and achieve the large capacity by 2 method wherein a gas flow path is provided at the part facing the windings inside the tank wall and insulating gas is forcibly convected. CONSTITUTION:A partition 8 jointed with the inner surface of the plate 10 of a gas flow path 9 is provided in a tank 3 to divide insulating gas 4 into upper and lower parts. The insulating gas 4 is circulated into a cooler a through the flow path 9 facing respective windings 2 by a blower 6. With this constitution, the thermal conductivity can be improved and the heating of the tank wall can be suppressed so that the large capacity can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a gas insulated transformer using an insulating gas such as SF6 gas as an insulating and cooling medium.

(Prior Art) Recently, as a non-flammable transformer that replaces an oil-immersed transformer, a non-flammable insulating gas (for example, SF6 gas) is used as a cooling and insulating medium instead of insulating oil.

So-called gas insulated transformers have been developed and have been put into practical use with capacities of several tens of MVA. In such a gas insulated transformer, although the insulating gas has improved insulation properties compared to the insulating oil of an oil-immersed transformer, its cooling properties are inferior. For this reason, the cooling method inside the iron core and windings is such that gas is forced to flow to improve the cooling characteristics. The cooling properties are K as obtained. To perform this forced convection, a blower is used to send insulating gas to the core and windings, and a differential pressure is applied between the inlet and outlet sides of the insulating gas tank to increase the gas flow velocity within the core and windings. A gas partition plate is installed to divide the inside of the tank into upper and lower parts.

(Problem to be solved by the invention) However, in such a gas-insulated transformer, leakage magnetic flux of the winding increases in a transformer with a large capacity or impedance voltage, and this leakage magnetic flux can cause damage to the metal structure inside the transformer. When linked to objects or tank walls, eddy currents are generated and heated. A similar phenomenon occurs in oil-immersed transformers, but as mentioned above, the cooling properties of insulating gas are less than 1/10 of insulating oil in natural convection, so gas-insulated transformers have a smaller capacity than oil-immersed transformers. , this problem becomes apparent even at low impedance voltages.

In oil-immersed transformers, as a countermeasure against overheating of the tank wall, an electromagnetic shield plate made of aluminum is installed on the inner wall of the tank to avoid concentration of magnetic flux, and a magnetic shield made of silicon steel plate prevents the concentration of magnetic flux from entering the tank wall. This has been dealt with by reducing the amount of magnetic flux, but similar measures are required for gas-insulated transformers. However, taking such measures will inevitably increase the cost of the transformer, such as higher material costs and increased manufacturing time for installation work, and also, due to the poor cooling characteristics, similar measures will not be necessary. However, sufficient cooling performance could not be obtained.

Unable to increase capacity.

The present invention has been made to solve the above-mentioned problems, and aims to provide a gas insulated transformer that prevents overheating of the tank wall without attaching a shield to the tank wall, is inexpensive, easy to manufacture, and is suitable for increasing capacity. do.

[Structure of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention provides a gas flow path in a portion of the inner surface of the tank wall facing the winding, and insulates the gas flow path. It is designed to force gas to flow.

(Function) Natural convection of insulating gas has poor cooling properties, but forced convection improves the heat transfer coefficient, making it possible to achieve a heat transfer coefficient equivalent to that of natural convection of insulating oil. If there is a distance of 4 m between the tank wall and
A gap of m is provided, and SF is applied at a flow rate of 4%'l within this gap.
When 6 gases are flowing, at a gas pressure of 1.25 kg/di, the heat transfer coefficient is approximately 110 w/rd°C, which is equivalent to the natural convection heat transfer coefficient of insulating oil.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

As shown in FIGS. 1 and 2, the iron core 1 and the winding 2 wound around the iron core 1 are housed in a tank 3 together with an insulating gas 4, and the inside of the tank 3 has an inlet side and an outlet side of the insulating gas 4. A partition plate 8 is provided at the top to provide a differential pressure between and to allow gas to flow into the iron core 1 and winding 2.

It is categorized below. Further, a gas cooler 5 is connected to the outside of the tank 3 via a blower 6.

On the other hand, an insulating plate 10 is attached to the inner surface of the tank wall 7 between the tank wall 7 and the winding 2 with a gap of, for example, about 4 ms from the tank wall 7. It is necessary to create a pressure difference between the gas inlet and outlet sides of the gas flow path 9.

Therefore, the above-mentioned partition plate 8 is joined to the inside of the plate 10 of the gas flow path 9, and the insulating gas 4 is directed upward at this portion.

Classify below. A gas stopper 1 is installed to prevent gas leakage at the joint between the partition plate 8 and the plate 10 of the gas passage 9. In addition, in order to secure a gap between the tank wall 7 and the plate 10,
As shown in the figure, a vertical spacer 12 is attached to the plate 10. The spacer 12 does not need to be as long as shown in the drawings, and may have any structure as long as it can ensure a gap. Also,
Since the temperature of the wall 7 increases significantly in the area near the winding, the mounting range of the plate 10 does not need to cover the entire circumference of the inner wall of the tank, but only on the surface close to the winding 2, as shown in Fig. 3. Is it okay to fix the plate 10 to the inner surface of the tank wall 7? Install the seat 13 for fixing the bolt, and attach the insulating bolt 1 to this 13/C plate 10.
Fix it at 4. In this way, the amount of insulating gas flowing in the gas flow path 9 becomes an amount that is balanced by the pressure loss when the insulating gas flows into the duct in the winding 2 and the iron core 1. Should the gap size of the gas flow path 9 be changed in order to adjust the flow rate?

It is easy to apply force to the adjustment piece to reduce the gas flow area.

[Effects of the Invention] As described above, according to the present invention, in an apparatus having a tank for storing an iron core and a winding, an insulating gas sealed in the tank, and a gas cooler for cooling the insulating gas,
An insulating plate is placed between the inner wall of the tank and the winding, and a gas flow path is provided between this plate and the inner wall of the tank, which prevents overheating of the tank wall and is inexpensive. A gas insulated transformer that is easy to manufacture and suitable for increasing capacity can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the gas insulated transformer of the present invention, Fig. 2 is an enlarged view of the main part showing the gas flow path in the present invention, and Fig. 3 is a plane showing the installation range of the gas flow path. It is a diagram. 1... Iron core, 2... Winding wire, 3... Tank, 4...
・Insulating gas, 5... Gas cooler, 7... Tank wall,
8... Partition plate, 9... Gas flow path, 10-... Board. Applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (1)

[Claims] In a gas insulated transformer having a tank for storing an iron core and a winding, an insulating gas sealed in the tank, and a gas cooler for cooling the insulating gas, there is a space between the inner wall of the tank and the winding. A gas insulated transformer characterized in that an insulating plate is arranged and a gas flow path is provided between the plate and the inner wall surface of a tank.