JPH0142121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises an insulated pipe having a fixed tap contact on the inner wall of a cylindrical oil container and located centrally inside the oil container, said insulated pipe carrying a movable contact and having a fixed tap contact at the upper end. It can be rotated step by step by a Maltese cross fixed to the contact, and three movable polarity switching contact bridges are provided around the insulating pipe between the tap contact and the Maltese cross, and the polarity switching The contact bridge cooperates with three fixed polarity switching contacts, each also located on the inner wall of the oil container, by means of a drive ring mounted on the upper end of the insulating pipe and rotatable in a finite manner relative to the insulating pipe. The present invention relates to a movable three-phase load tap selector for a tap-changing transformer.

With load tap selectors of this type, it is possible to test the entire load tap selector, ie even the polarization contacts, at defined intervals. However, the installation of the polarity switching contacts in the cylindrical oil reservoir of the load tap selector, while having the advantage of ease of inspection, also has certain disadvantageous consequences, particularly with regard to the voltage loading on the polarity switching contacts. Of course, in order to install a polarity switching contact in a cylindrical oil container, the circumference of the oil container must not be larger than the dimension determined from the tap contact. On the other hand, of course, care must be taken that the polarity switching contacts are not installed in the clean oil of the transformer, but in the increasingly dirty oil of the load tap selector.

The object of the invention is to utilize the limited free space as best as possible to obtain a high voltage strength at the polarity switching contact, while also avoiding the fact that oil gradually becomes contaminated inside the load tap selector and becomes covered with soot. The object of the present invention is to improve the load tap selector mentioned above, keeping in mind the fact.

This problem has been solved according to the invention in a three-phase load tap selector for a tap-changing transformer, in which each contact bridge of the polarity changer is located at the lower end of each one of the longitudinally extending pot-shaped insulation pipes. However, the insulation part is held by a drive ring and is solved in that a U-shaped contact bridge likewise extends in the longitudinal direction of the insulation pipe.

The advantages of the invention lie not only in making better use of the space freed up;
Above all, the purpose is to increase the voltage intensity in the moving parts of the polarity switch. If the entire circumference of the cylindrical oil container is used to install the fixed polarity switching contact, the circumference becomes significantly smaller at the location of the movable polarity switching contact because the movable polarity switching contact is inside. For example, by using three pot-shaped carriers for the movable polarity switching contact instead of a separate insulating pipe, and by arranging both the insulation carrier and the contact bridge of the polarization switch in the longitudinal direction. As a result, the spacing between the contact bridges, especially in the phase of the polarity changer, increases. Possible bridge formation due to soot deposits is therefore considerably hindered in the insulation parts.

Embodiments of the invention are illustrated in the accompanying drawings and described in detail below.

As can be seen from the figure, the new load tap selector essentially comprises a cylindrical oil container 1, closed by a bottom flange 2 and a cover 3, carrying a fixed tap contact 4, and a movable tap contact 6. An insulating pipe 5 mounted centrally inside the oil container, rotatable step by step by means of a Maltese cross 7 through a drive mechanism 8, not individually shown in detail, and a drive with tap contacts 4, 6. A polarity switch 9 is also installed inside the oil container 1 between the parts.
Insulating pipe 5 carrying movable tap contact 6
is mounted on the one hand in a bearing rest 10 of the bottom flange 2 and on the other hand is rigidly connected to the Maltese cross 7, which itself is mounted on the cover 3. An intermediate member 1 is provided at the upper end of the insulating pipe 5.
1 is surrounded by a drive ring 12 of the polarity changer 9, which is rotatable in a finite manner both relative to the cylindrical oil container 1 and relative to the insulating pipe 5. This drive ring 12 carries three pot-shaped insulating parts 13 which extend in the longitudinal direction of the oil container 1 or of the insulating pipe 5;
The lower end carries a U-shaped contact bridge 14 of each polarity changer 9. The drive ring 12 can be rotated in the usual way by an intermittent transmission mechanism, which is not shown in detail, by the required polarity switching step based on the position of the Maltese cross 7. During this polarity switching step, the contact bridge 14 , whose one end 16 is attached obliquely to the sector-shaped fixed polarity switching contact 17 , is moved from the first attached fixed polarity switching contact 19 with its other end 18 . It is moved to the second fixed polarity switching contact 15 installed on the same plane. Fixed polarity switching contact 1
5, 17 and 19 are fixed to the wall of the cylindrical oil container 1 in the same way as the fixed tap contact 4.
The entire circumference of the cylindrical oil container 1 is therefore used for the spacing between the individual fixed polarity switching contacts in one plane. In order to obtain a high voltage strength also between the movable contact bridges 14 of the polarity changer, three single insulators are used so that a free oil path exists between the individual phases of the movable part of the polarity changer 9. A portion 13 is provided, which prevents electrical bridge formation between the phases despite the smaller circumference compared to the oil container 1. This insulating material section 13 tapers towards its lower end, which carries the contact bridge 14, so that large oil passages are obtained here and there between the insulating material sections. A larger spacing between the movable contact bridges 14 can also be achieved by extending the contact bridges in the longitudinal direction of the insulating pipe 5. In order to prevent undesirable soot deposits on the insulation part 13, the insulation part is provided with a protrusion 20 running around it. In particular, this improves the voltage strength between the contact bridge 14 of the polarity changer 9 and the earth potential present in the drive part.

[Brief explanation of drawings]

The attached figure is a longitudinal sectional view of a load tap selector according to the invention. The main reference numbers in the figure are as follows. 5... Insulating pipe, 9... Polarity switch, 12... Drive ring, 13... Insulating material portion, 14... Contact bridge, 20... Convex portion.

Claims (1)

[Claims] 1. A cylindrical oil container having a fixed tap contact on the inner wall, an insulating pipe located at the center inside the oil container, the insulating pipe carrying a movable contact fixed at the upper end. It can be rotated step-by-step by means of a Maltese cross,
Three movable polarity switching contact bridges are provided around the insulating pipe between the tap contact and the maltese cross, and each of the said polarity switching contact bridges is also provided with three fixed polarity switching contact bridges located on the inner wall of the oil container. In a three-phase load tap selector for a tap-changing transformer, such a three-phase load tap selector for a tap-changing transformer is movable in cooperation with a contact by a drive ring mounted on the upper end of the insulating pipe and rotatable in a finite manner relative to the insulating pipe. Each contact bridge 14 of the polarity changer 9 is located at the lower end of a respective vertically extending bowl-shaped insulation portion 13 of the insulation pipe 5, said insulation portion being held by a drive ring 12. A three-phase load tap selector for a tap-changing transformer as described above, characterized in that the U-shaped contact bridge 14 likewise extends in the longitudinal direction of the insulating pipe. 2. A load tap selector according to claim 1, wherein the insulating material portion (13) tapers towards the end carrying the contact bridge (14). 3 Several protrusions 2 are provided in the insulating material part 13 between the polarity switching contact bridge 14 and the drive ring 12 transversely to the longitudinal extension and surrounding the insulating material part.
Claim 1 or 2 comprising 0
Load tap selector as described in section.