JPS59127818A - On-load tap-changing transformer - Google Patents

Abstract

PURPOSE:To eliminate instability of insulation characteristics by a simple shield composition by a method wherein a plurality of insulated conductors are put side by side on an insulation cylinder and all of their ends of one side are given the same potential as an end static shield and the ends of another side are open and the end insulation is applied to them to form a shield. CONSTITUTION:A low-voltage winding is wound over a main core leg with an insulation member in between and a high-voltage winding 3 is wound over the low-voltage winding with an insulation member in between and then an insulation cylinder 11 is put over the high-voltage winding 3. A plurality of insulated conductors 12 are arranged side by side with a certain spacing in parallel to the direction of the shaft. Over the insulated conductors 12, thus arranged, a tap winding 4 is wound using the insulation cylinder 11 as a winding core and an end static shield 13, which has an insulation layer 13a, is provided to the end of the tap winding 4. The ends of one side of a plurality of the insulated conductors 12 are connected to the end static shield 13 and the conductors have the same potential as the shield 13. The end static shield 13 is either grounded or kept at the neutral potential. The ends of another side of the insulated conductors 12 are either fixed to the insulation cylinder 11 after each end is insulated or drawn out of the winding.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates particularly to on-load tap-changing transformers with improved shielding between high voltage windings and tap windings.

[Technical background of the invention and its problems]

In order to provide the transformer with a voltage regulation function, the on-load tap changer transformer consists of a low voltage winding (2) and a high voltage winding (3) that are concentrically wound around the iron core leg (1), as shown in Figure 1. A tap winding (4) may be wound around the outer circumference. In addition (6
) is a changeover switch, (7) is a tap contact, and (8) is a movable contact.

In such an on-load tap changing transformer, when changing the tap of tap winding (4), tap winding a (4)
The electrostatic capacitance formed by the high voltage winding (3) and the tap winding (4) and the electrostatic capacitance formed between the tap winding (4) and the tank or core side leg are applied to the voltage corresponding to one tap of Capacity υ
Since the electrostatic transfer voltage from the high-voltage winding (3) is shared by the inter-winding capacitance and superimposed on the tap voltage, a voltage higher than the withstand voltage of the tap changer may be applied. For this reason, in this type of transformer, the high voltage winding (
A shield (5) is disposed between the tap winding (4) and the tap winding (4) to reduce electrostatic transfer voltage superposition from the high voltage winding (3) to the tap winding (4). Although not shown, this shield (5) is made of metal or other conductive material that does not conventionally constitute a one-turn circulation circuit.

However, since the shield (5) does not constitute a one-turn circulation circuit and must be arranged concentrically,
There were the following problems.

(1) Eddy current loss occurs when multiple windings are made on one large metal plate, so after winding many narrow tape-shaped metal strips, cut them in the axial direction so as not to form one turn, and then The metal plates are arranged in the axial direction and the potential of the entire shield (5) is fixed, resulting in poor workability.

(11) Since the tape-shaped metal faces the high-voltage winding (3), when increasing the voltage and making it more compact, there are problems with insulation, such as occurrence of partial discharge or breakdown.

(iii) Due to the drying process of the transformer windings, shrinkage of the insulator may create an oil gap between the shield (5) and the insulator, and shrinkage of the insulator may cause deformation and strain in the shield (5). There is a risk that this may occur.

hJ It is difficult to insulate the axial end.

Compared to the past, the above problems have been solved by power/-? - Therefore, during manufacturing, attention must be paid to these matters, which also increases the number of man-hours and leads to excessive insulation design due to insulation instability.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and aims #i to improve reliability and workability by providing a simple and simple shield structure and eliminating instability in insulation performance. An object of the present invention is to provide an on-load tap-changing transformer that can perform the following functions.

[Summary of the invention]

In order to achieve this object, the present invention arranges a plurality of insulated conductors in the axial direction of the insulated tube on the insulated tube that serves as the winding core of the tap winding, and all of the insulated conductors are arranged in a magnified manner in the axial direction of the insulated tube. By forming a shield by insulating the end with the same potential as the electric shield and leaving the other end open, the shield structure is simple, and instability in insulation performance is eliminated, improving reliability and workability. This is its characteristic.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An on-load tap-changing transformer according to an embodiment of the present invention will be described below with reference to the drawings. The same parts as in FIG. 1 are given the same reference numerals. In Figure 2, a low-voltage winding is wound around the main leg of the core (not shown) via an insulating member, a high-voltage winding (3) is wound on top of the main leg through an insulating member, and an insulating tube aυ is attached. do. A plurality of insulated conductors α are arranged above the insulating cylinder clυ in parallel to the axial direction at regular intervals. The tap winding (4) is wound on the nine insulated conductors a3 arranged in this way using the insulating tube I as the winding core.
) is provided with an end electrostatic shield a3 having an insulating layer (13a). A plurality of insulated conductors a2 are connected to the end electrostatic shield (13) so that they have the same potential, and an end electrostatic shield (13 is not shown, but is grounded or has a neutral point potential. On the other hand, the insulated conductor Q2 The other end is either insulated and fixed to the insulating tube αυ, or pulled out to the outside of the winding.In addition, the tap winding (4) is equipped with a switching device consisting of a tap contact and a movable contact (not shown). Attach the switch to form a tap changer.

Next, the effects of the present invention will be explained. The tap winding (4) of the on-load tap-changing transformer constructed in this way has one end made up of an insulated conductor with the same potential as the end electrostatic shield.
As a result, electrostatic transfer from the high voltage winding (3) is suppressed, so severe voltage is not applied to the tap changer.
The insulation reliability is improved by simply switching the voltage between the taps.

Further, in manufacturing, the insulated conductor Q3 can be placed on the insulating tube 0υ in the same way as a duct piece in manufacturing the winding of a general transformer, so manufacturing is easy and the manufacturing time can be shortened. Each insulated conductor a′! The spacing of J can be selected appropriately (depending on the insulation distance from the high voltage winding (3)), and the insulated conductor σ
2 has an insulating coating, so even if mechanical forces such as drying and tightening are applied, no oil gaps will be formed on the metal surface of the insulated conductor tta, resulting in stable insulation without reducing dielectric strength. The configuration is obtained.

Next, another embodiment of the present invention will be described. Tap winding (4)
An end electrostatic shield (Ial), for example, an insulated conductor (by providing appropriate rounding and insulation at the part corresponding to the end electrostatic shield 0 row shown in Fig. 2), It is also possible to omit the electrostatic shield (13), resulting in a significant reduction in man-hours compared to conventional tap winding production.In this case, the potential of the insulated conductor is fixed at either the upper or lower end. The effect will not be impaired regardless of whether the insulated conductor is used at one end.Furthermore, any conductor whose surface is coated with insulation, such as a rectangular copper wire or a transposed cable, can be used as the insulated conductor at the zero end.

〔Effect of the invention〕

As explained above, according to the square load tap-changing transformer of the present invention, a shield that is easy to manufacture and has a stable insulation structure can be obtained, and reliability and workability can be improved.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional on-load tap-changing transformer.
FIG. 2 is a sectional view showing the main parts of the on-load tap-changing transformer of the present invention. (1) Iron core main landing gear, (2)...low voltage winding, (3)
High-voltage winding, (4)...Tap winding, 01) Insulated tube, alpha ripple/insulated conductor, zero rise/end electrostatic shield, Agent: Patent attorney Inoue-male Figure 1

Claims (1)

[Claims] A low-voltage winding, a high-voltage winding, and a tap winding are wound around an iron core and housed inside a tank, and an insulating tube is provided between the high-voltage winding and the tap winding, and the insulating tube is A plurality of insulated conductors are arranged on the outside in parallel with the axial direction of the insulating cylinder, and the tap winding is provided on the insulating cylinder through the insulated conductor, and the tap winding of the An on-load tap change transformer, characterized in that an end electrostatic shield provided at an end portion and one end of each of the insulated conductors are at the same potential, and the other ends are respectively insulated.