JPH0519937Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the structure of insulated leads for electrical equipment, particularly insulated leads used in high voltage oil-immersed transformers and the like.

Figure 1 is an overall configuration diagram of this type of conventional oil-immersed transformer using insulated leads, Figure 2 is an enlarged sectional view of the insulated leads in Figure 1, and Figure 3 is the
FIG. 3 is an explanatory diagram showing the direction of heat dissipation of the insulated leads shown in the figure. In the figure, 1 is a tank containing insulating oil 2, 3 is a coil having an opening 3a and to which voltage and current are applied, 4 is an iron core arranged to interlink with the coil 3, and 5 is a An insulator for insulating between the coils 3 and between the coil 3 and the iron core 4 and the tank 1, 6 a bushing having an oil-immersed terminal part 6a and installed through the tank, and 7 an open end. The solid conductor 8 is an insulated lead whose other end is electrically connected to the oil-immersed terminal part 6a in the part 3a.
and an electrically insulating layer 9 made of kraft insulating paper or the like formed on its outer periphery. Reference numeral 10 denotes an electric field relaxation shield attached to the oil-immersed terminal portion 6a. 11 is a cooling device connected to the tank 1 via an oil pipe for cooling the insulating oil 2, and 12 is an oil pump for forcibly circulating the insulating oil 2 in the direction of the arrow 13.

In the insulated leads of the conventional oil-immersed transformer configured as described above, the heat generated in the insulated leads 7 due to current conduction is absorbed by the electric insulating layer in the radial direction of the solid conductor 8, as shown by the arrow 14 in FIG. The required cross-sectional area of the solid conductor 8 is therefore set from the thermal resistance during this time and a predetermined allowable temperature rise value.

However, in the insulated leads of the conventional oil-immersed transformers as described above, the thickness of the electrical insulating layer 9 becomes extremely large when the voltage is high, such as in a UHV class transformer. is a poor conductor of heat and the thermal resistance of this part increases, so
The required cross-sectional area of the solid conductor 8 becomes extremely large, resulting in an increase in material cost and poor workability.

This idea was made to eliminate the drawbacks of the conventional ones, and by constructing a hollow conductor with an electrically insulating layer formed on the outer circumferential surface and an insulating refrigerant flowing inside, the refrigerant can flow inside the conductor. The purpose of this invention is to provide an insulated lead for electrical equipment that is directly cooled from the heat source, is inexpensive, and has good workability.

Hereinafter, an insulated lead for an oil-immersed transformer according to an embodiment of this invention will be described with reference to the drawings. Figure 4 is an overall configuration diagram of the oil-immersed transformer, Figure 5 is an enlarged sectional view of the insulated leads in Figure 4, and Figure 6 is the heat dissipation and oil flow of the insulated leads in Figure 4. FIG. In the figure, a tank 1, insulating oil 2, coil 3, outlet 3a, iron core 4, insulator 5, bushing 6, oil-immersed terminal 6a, electric field relaxation shield 10, cooling device 11, oil pump 12, oil flow Since the arrow 13 is the same as in the conventional case, a description thereof will be omitted. 15 is a hollow conductor with an electrical insulating layer 16 formed on its outer peripheral surface; 17 and 18 are hollow conductors 15;
A pair of connecting terminals are fixed to both ends of the hollow conductor 15 to allow the insulating oil 2 to flow through the inner diameter of the hollow conductor 15.
are located at the center of the inner diameter part of the coil and are connected to each other so as to be energized, and each has a coil outlet 3.
a and the oil-immersed terminal portion 6a are connected. The insulated lead 19 is composed of a hollow conductor 15, an electrically insulating layer 16 on its outer peripheral surface, and a pair of connection terminals 17 and 18, and the coil outlet 3a side of the insulated lead 19 is spaced appropriately from the surroundings. The submerged terminal portion 6a side is provided with an appropriate distance from the electric field relaxation shield 10 and the submerged terminal portion 6a of the bushing.

In the insulated lead 19 of the oil-immersed transformer of this invention constructed as described above, the heat generated by energization of the hollow conductor 15 is released toward the inner diameter side of the hollow conductor 15 as shown by the arrow 23 in FIG. The heat generated by the connecting terminals 17 and 18, which generate heat, is also transferred to the insulating oil 2, and the temperature of the insulating oil 2 rises, resulting in a so-called thermosiphon effect, which causes an oil flow to rise up the inner diameter of the hollow conductor 15. Therefore, a good cooling condition is achieved regardless of the thickness of the electrical insulating layer 16 on the outer peripheral surface, so the necessary cross-sectional area of the hollow conductor 15 can be reduced, and the conductor can be made lightweight and inexpensive. A good cooling effect can be obtained without using any means for forcibly obtaining an oil flow.

Note that insulating refrigerants include not only insulating oil but also SF ₆ .
It can also be applied to insulating gases such as gases. Further, the insulating lead 19 can be used not only in transformers but also in various electrical devices such as reactors, as long as electrical insulation is required and the purpose is to conduct electricity between current-carrying parts of the electrical device.

As explained above, the insulated lead is made of a hollow conductor with an electrically insulating layer formed on the outer circumferential surface and open at both ends so that an insulating refrigerant flows through the inner diameter, and the center of the inner diameter of both ends is By providing a connection terminal on each side and arranging the two ends so that there is a difference in height, the heat generated by energization of the hollow conductor and the connection terminal is transmitted to the insulating oil inside the hollow conductor, and the temperature rise of the insulating oil causes the thermosifter to Cooled by on-effect refrigerant flow. In particular, placing the connection terminal at the center of the inner diameter of the hollow conductor has the effect of effectively cooling this part and accelerating the refrigerant flow due to the thermosiphon effect, so it is recommended to use a means to force the refrigerant flow. Since a coolant flow can be obtained without any problem, and a good cooling condition can be achieved regardless of the thickness of the electrical insulating layer on the outer circumferential surface, there is an effect that a lightweight and inexpensive insulated lead with a reduced required cross-sectional area of the hollow conductor can be obtained.

[Brief explanation of drawings]

Figure 1 is an overall configuration diagram of an oil-immersed transformer using conventional insulated leads, Figure 2 is an enlarged cross-sectional view of the insulated leads in Figure 1, and Figure 3 is the insulated leads in Figure 1. Fig. 4 is an overall configuration diagram of an oil-immersed transformer using insulated leads in an embodiment of this invention, and Fig. 5 is an enlarged view of the insulated lead portion of Fig. 4. FIG. 6 is an explanatory diagram showing the direction of heat dissipation and oil flow of the insulated lead shown in FIG. 4. In the figure, 2 is an insulating oil as an insulating refrigerant, 3a is an opening part as a current-carrying part of an electric device, 6a is a submerged terminal part as a current-carrying part of an electric device, 15 is a hollow conductor, 16 is an electric insulating layer, 1
7 and 18 are a pair of connection terminals, and 19 is an insulated lead. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] An electrical equipment main body consisting of a coil and an iron core stored together with an insulating refrigerant inside a tank, a bushing installed through the tank, an outlet part of the coil, and an oil-immersed terminal part of the bushing. The insulated lead consists of a hollow conductor that is open at both ends, and an insulating part that insulates the outer periphery of the hollow conductor. Connecting terminals that allow the medium to flow and have a connecting portion at the center of the inner diameter of the hollow conductor are connected to both ends so as to be electrically conductive, and one of the connecting portions has an outlet portion of the coil, and the other connecting terminal has a connecting portion at the center of the inner diameter of the hollow conductor. An oil-immersed terminal portion of a bushing is connected to the portion, and both ends of the hollow conductor are arranged so as to have a difference in height from each other.