DE3038705A1 - Current transformer with annular head - has divided primary conductors in outer head section with inner section through head and brought out terminals - Google Patents

Abstract

The current transformer part with annular head is enclosed in a housing. Round the head are arranged switchable primary conductors in at least one winding turn. The primary conductors (4) are divided in an outer section arranged round the outer periphery of the head (8). Through the latter is passed an inner section (4) of the primary. The terminals of the sections are brought out from the housing (9,10). Preferably the outer sections are embedded in casting resin (1). For this purpose a surrounding plastics ring may be provided for retaining each semi-circular outer section. Through apertures for the inner sections may be provided in the plastics ring near the outlet apertures for the outer sections. A solid conductor can be used as the inner sections. In one embodiment four inner sections and three outer sections may be used.

Description

Top current transformer

The present invention relates to an overhead current transformer with a current transformer part with an annular head accommodated in a housing and primary conductors which can be switched in at least one winding around the annular head are.

Such top current transformers belong to the state of the art, they serve to transform larger currents in order to allow them to be measured by ammeters to make accessible. The current transformers are conventionally manufactured so that the required number of windings with the help of stranded conductors around the ring-shaped Head of the current transformer part are wound.

The current transformer part is usually bandaged for insulation.

This method of assembly is relatively laborious and consequently labor-intensive. The object of the invention is to manufacture top current transformers to simplify.

The object is achieved in that the primary conductors are divided into an outer section guided past the outer circumference of the annular head and an interior portion passing through the annular head, with terminals on guide the two sections out of the housing.

The division of the primary conductor into inner sections and outer sections leads to. that a stranded wire is not wound around the ring-shaped current converter part towards the head must be, but that the two sections are prefabricated and used separately can be.

In the event that the primary conductor does not just turn in one turn the annular head is to be passed through, but a winding around the Ring is to be formed on the connections led out of the housing to the outside Connections are provided with the help of which the intended current flow is established can be.

A preferred embodiment provides that the outer sections are embedded in plastic, preferably cast resin. This manufacturing has different Advantages. On the one hand, this makes it possible to combine the outer sections in one Gießhar 'component to accommodate, which are prepared separately from the top current transformer production can and can be introduced as a prefabricated unit during assembly.

Another factor is the dynamic strength of the head current transducer an extraordinarily large problem, especially in the case of short-circuit current loads. The stranded wire according to the prior art must be attached to the current transformer part which makes additional work steps necessary. There is also the risk of that this stranded conductor is in contact with the outer conductive layer of the current transformer part come, which cause damage, especially with dynamic loads can. However, by the structure in this preferred embodiment, the outer portions determined by the embedding in plastic, in particular cast resin, the Cast resin is readily able to cope with dynamic stresses to become.

Furthermore, the outer sections no longer come into contact with the outer guidance position. Thus, with simplified production, the fastening problems arise at the same time solvable in the manner according to the invention.

It is favorable that for embedding the outer sections a opf surrounding plastic ring is provided, which each half-ring-shaped outer sections records. This embodiment is very easy to carry out in terms of production technology. A ring is cast in which the outer sections are embedded and the, usually around 900 opposite your ring-shaped head of the current transformer part pivoted, the outer sections on both sides of the head. Included semicircular outer sections are guided past both sides of the head.

Another favorable embodiment is that in the plastic ring In the vicinity of the outlet openings for the outer sections, through openings for the interior sections are provided. The plastic ring forms in this way at the same time the insulated holder for the inner sections. It will be in the plastic ring Openings which are adapted to the cross-sectional shape of the inner sections are provided and the inner portions held by the ring are formed through the center of the ring-shaped Head passed through. The outlet openings of the inner sections and the outer sections are then close together in this case.

Solid conductors are usually provided as inner sections. Such Conductors are best able to cope with the high currents and at the same time are easy to manufacture and also offer sufficient mechanical strength when forces are exerted by the thermal and dynamic short circuit current.

An embodiment that is important for practical use provides that four inner sections and three outer sections are provided. It can be make several switchings in this way, in particular the one for practice essential 1: 2: 4 primary switching possible in this way.

It proves to be advantageous that the emerging from the housing Connections for the sections can optionally be connected with switch tabs. By these switch tabs easily create the circuit between each Primary inner sections and primary;, tl section sections closed, whereby the number of turns can be adjusted by removing or attaching the switch tabs is.

One possibility of execution is that the one made in cast resin Plastic ring is integrated into the housing and on its upper and lower sides Has sealing grooves for connection to the upper part of the housing and the lower part of the housing. Since the inside of the housing is usually filled with insulating oil, it must The housing of the top current transformer is designed to seal against the oil outlet be. rs is therefore provided in this embodiment of the invention that on the lower housing part, which closes off in a ring shape at its upper part, the cast resin ring is placed, with a groove in the cast resin ring receiving, for example, an O-ring seal. At the same time, the openings for the primary inner conductor are provided in the cast resin ring. Furthermore, as already described, the primary outer conductors are embedded in the casting ring. The top of the cast resin ring in turn has a groove that forms the seal of the upper part of the housing, which closes the top current transformer like a cover, against the Cast resin ring ensures.

It goes without saying that within the scope of the present invention other geometric shapes than that of an exactly circular cast resin ring are possible. In particular, given by the shape of the outer conductor and the current transformer part, the cast resin embedding for the outer sections approximate the rectangular shape. Just in these cases are the problems of adaptation and the difficulties involved the seal through the cast resin cover, the upper and lower parts together connects, particularly easy and elegant to solve.

The invention is described below with reference to the figures: Fig. 1 shows various wiring options for the current transformer according to the invention; 2 shows the cast resin part with its outlet openings for outer and inner sections; and FIG. 3 shows a section through the head structure according to the invention.

A top current transformer according to the invention is shown in the figures. The lower end of the top current transformer is formed by the insulator 11 on which the lower housing part 9, which includes the top current transformer, is seated. The upper edge of the lower part of the housing 9 is completed by the cast resin ring 1, on which in turn the upper part of the housing 10 is put on. Close housing lower part 9, cast resin ring 1 and housing upper part 10 the annular head 8 of the current transformer.

Usually, the annular head 8 lies in the vertical, whereas the cast resin ring 1 is horizontally aligned i ~ v.

In the cast resin ring 1, the outer sections 2 are embedded, the thus also lie in the horizontal and guided around the ring-shaped head 8 on the outside will. With the help of switching pans 3 connections of the outer sections are made the cast resin ring 1 outwards.

Furthermore, openings are provided in the cast resin ring through which the primary conductor inner sections 2, which are preferably designed as solid conductors Appropriate seals at the outlet openings are inserted through prevent the leakage through the lower housing part 9, the cast resin ring 1 and the upper housing part 10 icing oil included.

There are still primary connections on the outside of the housing 6 provided through which the power is supplied or

is removed.

The primary connections 6 must be used to produce a current flow Using switch tabs 5 with the corresponding number of primary conductor sections get connected.

The various wiring options can be found in FIG. 1 will. In order to achieve a turn, for example, all of the inner sections can be connect in parallel, the outer sections will not be in at all operation taken. In order to verify further practical wiring options, it is advisable to have one inner section and three outer section. Then lets For example, to achieve two turns, an inner section on one Connect one side to the primary connector, on the other side with an outer section. This outer section leads the current back again and becomes at its other end connected to a further inner section, the one on its opposite side is linked to the outgoing primary connection. With the help of four interior sections and two outer sections, two such turns can be connected in parallel.

Finally, there is the option of using the four Wincungen different sections by placing all sections alternately inside and outer sections, to be connected in series.

Preferably, the cast resin ring 1, which, depending on the geometric conditions, does not necessarily have to form a circular ring on its A sealing groove 7 on the top or bottom to ensure the sealing effect between the upper part of the housing 10 or lower housing part 9 and the cast resin ring 1 to improve.

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Claims (9)

PATENT CLAIMS 1) top current transformer, with) one in a housing housed current transformer part with ring-shaped head and b) primary conductors, the are switchable in at least one winding around the ring-shaped head, characterized in that that c) the primary conductors (2, 4) are divided into one on the outer circumference of the annular Head passed outer section (2) and d) one through the annular head (8) leading inner section (4), where e) connections to the sections from the Guide out the housing (9,10). 2) top current transformer according to claim 1, characterized in that the Outer sections (2) are embedded in plastic, preferably cast resin (1). 3) top current transformer according to claim 2, characterized in that for Embedding of the outer sections (2) a plastic surrounding the head (8) (1) is provided, which receives the respective semicircular outer sections (2). 4) top current transformer according to claim 3, characterized in that in the KunsQ * dRring (1) near the exit openings for the outer sections through openings are provided for the inner sections (4). 5) top current transformer according to claims 1 to 4, characterized in that that solid conductors are provided as inner sections (4). 6) top current transformer according to one of claims 1 to 5, characterized in that that four inner sections (4) and three outer sections (2) are provided. 7) top current transformer according to one of the preceding claims, characterized characterized in that the connections emerging from the housing (9,10) for the sections can optionally be connected with switch tabs (5). 8) top current transformer according to claim 7, characterized in that the Connections by extending the sections themselves through the housing are formed. 9) top current transformer according to one of claims 1 to 8, characterized in that that the plastic ring (1) is integrated into the housing and at its upper or Sealing grooves (7) on the lower sides for connecting to the upper part of the housing (10) and the lower part of the housing (9).