DE2939934C2 - Current transformer with a core shell - Google Patents

Description

35

The invention relates to a current transformer with a core shell in which at least one iron core is located is held with applied secondary winding by means of fastening means.

In a known current transformer of this type (US-PS 33 80 009) contain the fastening means U-shaped support part, which with its bent legs the iron cores on their one implementation facing sections encompassed. The bent legs carry welded approaches with a Threaded hole into which fastening bolts are screwed; the fastening bolts are in turn guided through holes of a fastening device. By tightening the fastening bolts, the Iron cores with secondary winding together with the U-shaped bent support part against the fastening device pressed, with the core shell being fixed at the same time.

The fastening means of the known current transformer are therefore designed to be relatively complicated; the known current transformer is therefore also with regard to the mounting of the iron cores in the core shell in the Assembly relatively complex.

There is also a transformer with housing known (DE-GM 69 16 811), in which the inner spaces be filled with a filler made of a casting resin with a high proportion of a filler a material with good thermal conductivity. In the case of the known transformer, there is thus a Filling the gaps with a certain casting resin.

Furthermore, an encapsulated coil is known (DE-AS 18 11 797), which has an insulation made of synthetic resin The insulation is constructed in such a way that it contains staple glass fibers or fibers made of plastic with a length of 1 to Contains 20 mm; these fibers are filled by the resin compound during casting, so that cracks due to Shrinkage of the resin composition can be completely avoided.

The invention is based on the object of proposing a current transformer with a core shell which is the at least one iron core with applied secondary winding in a simple manner in the Can attach core shell

In order to achieve this object, there are according to the invention in a current transformer of the type specified at the outset the fasteners made of resin-impregnated plastic particles that fill the space between the Fill the iron core with the secondary winding and the core shell; the plastic particles are due to heat treatment glued to each other and to the core shell and the iron core with secondary winding

A major advantage of the current transformer according to the invention is that its fastening means consist only of resin-impregnated plastic particles that have any shape can and only have to meet the requirement that they compared to the dimensions of the room between the core shell and the iron grain relatively are small. Such plastic particles are easy to obtain and therefore with little effort Available. In addition, it can be introduced into the core shell in a simple manner. There the heat treatment of the plastic particles in the filled state can also be carried out with little effort is, the current transformer according to the invention can be with respect to the support of its at least one Manufacture iron core with secondary winding in the core shell with very little effort. Another The advantage of the current transformer according to the invention is that the bonding of the individual plastic particles takes place in such a way that, in the case of a current transformer filled with oil, the in The core shell heat generated by the windings is possible because the oil is between the plastic particles can fill the remaining small spaces well.

As already indicated above, the plastic particles can have almost any shape. For reasons of cost in particular, however, it is considered advantageous if the plastic particles are shell-like plastic bodies that are common in the packaging industry. Such Namely, plastic bodies can be obtained easily and at low cost.

However, it can also be advantageous to use thread-like plastic elements as plastic particles. Such plastic elements are also commercially available and can be made available at low cost. If necessary, it can also be appropriate, instead of thread-like plastic elements, of similar design Body made of wood — wool materials to be used.

With regard to the plastic particles, the only requirement to be met is that they are at the required Heat treatment does not change their external shape, for example do not melt.

In another embodiment of the current transformer according to the invention, the plastic particles are advantageously part of a foamed plastic with large, open pores. Even with such formed plastic particles can be the fastening

supply of the at least one iron core with applied Achieve secondary winding in the core shell with little effort. The large, open pores allow a: I here in the case of an insulated current transformer oil access to the pores, so that a derivation of the the warmth generated by the windings is made possible in a sweet way

It is already known (DE-GM 70 20 538), with a single-line bushing current transformer for encapsulated Generator discharge lines the housing of such a converter with a complete, gas-impermeable Sealing in the area of the housing to be filled with foamed plastic, however Here the plastic has a closed cell structure. The foamed plastic is not used for Holder of the iron core with secondary winding in the housing.

In the current transformer according to the invention with resin-impregnated plastic particles or with foamed Plastic, the plastic particles advantageously contain a thermally conductive substance. at this substance can be, for example, quartz powder. Plastic particles formed in this way allow the heat generated by the windings to be dissipated to the outside particularly well.

To explain the invention, in the figure, in section, that in connection with the invention shown essential part of an embodiment of the current transformer according to the invention.

The current transformer 1 shown contains a housing 2 which is filled with oil, for example. The housing 2 is designed toroidally and has a passage 3 on, through which a primary conductor 4 is passed.

Inside the housing 2 there is a core shell 5, which in a manner not shown in Housing 2 is held in a predetermined position. In the core shell 5 there are three iron cores 6, 7 and 8 with applied secondary windings, not shown in detail. The space between the seeds 6 to 8 and the core shell 5 is impregnated with resin Plastic particles 9 filled. These plastic particles form after heat treatment and hardening Support skeleton that holds the iron cores 6 to 8 firmly in the core shell 5 It is not necessary to hold the iron cores 6 to 8 in the core shell 5.

Secondary outlets 10 of the secondary windings are in the usual way within a bushing 11 out, which is located at the bottom of the housing 2 of the current transformer 1

The invention proposes a current transformer with a core shell, in which the at least one iron core with applied secondary winding can be attached in a simple manner as a result of the use of plastic particles filling the space between the at least one iron core and the core shell.

1 sheet of drawings

Claims (5)

Patent claims: 1. Current transformer with a core shell in which at least one iron core with attached secondary winding is held by means of fastening means, characterized in that the Fasteners made from resin-impregnated plastic particles (9) consist of the space between the iron core (6, 7, 8) with secondary winding and the core shell (5) fill, and that the plastic particles (9) as a result of heat treatment with one another and are glued to the core shell (5) and the iron core (6, 7, 8) with a secondary winding. Z current transformer according to claim 1, characterized in that the plastic particles (9) are shell-like plastic bodies common in the packaging industry. 3. Current transformer according to claim 1, characterized in that the Kunststoffteilcheri thread-like Plastic elements are. 4. Current transformer with a core shell in which at least one iron core with attached secondary winding is held by means of fastening means, characterized in that the fastening means made of plastic particles that form the space between the iron core with secondary winding and fill the core shell, and that the plastic particles are part of a foamed Are plastics with large open pores. 5. Current transformer according to one of the preceding claims, characterized in that the plastic particles contain a thermally conductive substance.