FR2484129A1 - HIGH VOLTAGE MEDIUM AND HIGH FREQUENCY TRANSFORMER - Google Patents

Abstract

HIGH VOLTAGE MEDIUM AND HIGH FREQUENCY TRANSFORMER, CHARACTERIZED IN THAT IT IS CONSTITUTED BY HOLLOW CONDUCTORS FULLY COOLED BY THE CIRCULATION OF A REFRIGERANT FLUID AND IN THAT THE WINDINGS 1, 6; 2, 3, 4, 5 ARE COILS TWO BY TWO IN REVERSE DIRECTION AND SET IN PARALLEL TO ALLOW E-E INTRODUCTION AND S-S EVACUID OF THE REFRIGERANT FLUID AT ZERO POTENTIAL.

Description

The present invention relates to a high voltage transformer with

  medium and high frequencies. It is known that aperiodic generators used for high and medium frequency heating consist of two parts. on the one hand the generator itself and on the other hand an oscillating circuit which includes the inductor and the capacitors these two parts being connected by an aperiodic transformer which

is the centerpiece of the generator.

  At present these aperiodic transformers are produced using insulated copper foil strips

  by a special film with low dielectric losses. This dis-

position allows very compact transformers to be produced with excellent efficiency. However, known transformers have the following disadvantages by constitution: - the voltage gradient in the coil is very high, which makes it difficult to avoid strikes between turns

  - their very structure does not allow suitable cooling

  filler which leads to a rise in temperature at the heart of the transformer and consequently a deterioration of the insulators X - they have a distributed capacity, source of parasitic connection between the generator and the oscillating circuit. This invention proposes to provide a transformer

  aperitif without the above drawbacks.

To this end, it targets a high voltage transformer with

  medium and high frequencies, characterized in that it is

killed by creUx conductors fully cooled by the

  circulation of a coolant and in that the

elements are wound two by two in opposite directions and put in parallel

the the. The combination: hollow conductors traversed by a coolant and winding in opposite directions of the windings ensures perfect cooling of the transformer while allowing

  the introduction and evacuation of the coolant to a point

  zero tential, which removes most of the related easements

refrigerant.

According to the invention the hollow conductors are preferably

tubular conductors with circular or rectangular sections

  laires with rounded edges, presenting no sharp angle in order to avoid the corona effect. Preferably the conductors are

2 2484129

  covered with an insulating sheath, for example in "Teflon", without

no discontinuity.

The invention also relates to a transformer as defined

above, transformed into an auto-transformer by a con-

  xion outside the magnetic circuit to avoid creation

half a turn.

  Other features and advantages of this invention

will emerge from the description given below with reference to

  appended drawings which illustrate various examples of embodiment devoid of any limiting nature. On the drawings

- Figure 1 shows schematically a transformer

  aperiodic mater according to the invention;

  - Figure 2 schematically illustrates a self-transforming-

  matrix derived from the transformer according to figure 1, and - figure 3 schematically represents the arrangement

  turns and insulators of the auto-transformer shown

felt in figure 2. -

  Figure 1 shows schematically a transformer

according to the invention.

  The secondary winding 1 is placed in the center of the coil, then two layers 2, 3 of the primary winding are arranged, the end of this winding being connected to the high voltage, then two other layers are wound in the opposite direction. , of the primary winding and finally outside, the last layer of the secondary winding 6 is wound, in the opposite direction

of layer 1.

  In this figure 1 we have designated by E and E 'the inputs

  refrigerant and by S and S 'their respective outputs.

We see that in the various windings the fluid of re-

  coldening is introduced and is evacuated to ground potential. Figure 2 illustrates an auto-transformer derived from

transformer shown in Figure 1.

  The secondary winding II comprising a single layer is placed in the center of the coil, then two layers 12, 13 of the primary winding are arranged, the end of this winding being connected to the potential of the anode A. Next are

  wound in opposite directions, two other layers 14, 15 of the

  primary bearing and finally outside the last layer 16

  this the secondary winding, wound in opposite direction to the first

layer 11.

In this figure 2, we see that in the different windings

Lements, the coolant circulates well in series and goes from the mass to the mass while passing by the highest potential. By cons, electrically the two primary are mounted in parallel as well as the two secondary. We also see that the connection between two layers is made so that the tension between two turns of successive layers does not exceed

  not the tension between the extreme turns of a layer.

  In Figure 3 we have schematized the relative arrangement

turns and insulators.

  This figure shows schematically at 20 the magnetic circuit

tick. The first inner turn 11 of the second winding

  daire is soldered on a rigid copper sheet 11 'covering

  the entire height of the winding. This copper foil serves as a

  tension notch between the windings and the magnetic circuit 20. The other turns of the secondary are wound around this first turn which is isolated inside and on all

  its height by an insulating sheet T for example in "Teflon".

  The last outer coil 16 is produced in an identical manner.

  The primary consists of two layers insulated from each other and from the secondary by an insulator, preferably a sheet of "Teflon" T. The whole of this winding is molded

  in araldite. The cooling of the conductors being par-

  fact, there is no need to fear the risk of dilation, dilata-

  tions that could cause cracks in the long term altering

  the electrical isolation of the assembly ..

  The magnetic circuit 20 is of the battleship type: it is

made up of U ferrites.

Alternatively, if the supply of coolant

  dissement allows, we can remove the reverse windings.

  For this purpose an insulating fluid column is formed and the outer layer of the winding of the winding is very carefully isolated.

  magnetic circuit. A good result is obtained by 10 mm of aral-

said and 10 mm of air. In this case it is better to climb

  the entire transformer on isolation pads.

  Of course, this invention is not limited to

  mitée with the examples of realization described and represented but

  that it encompasses all variants.

RLVEiNLCATICN S

  1.- High voltage transformer at medium and high fre-

  quences, characterized in that it is constituted by conduc-

hollow cores fully cooled by the circulation of a coolant and in that the windings (1,6; 2,3,4,5) are wound in pairs in opposite directions and placed in parallel to allow introduction (E- E ') and an evacuation (S-S')

refrigerant with zero potential. -

  2.- transformer according to claim 1, characterized in that the hollow conductors are tubular conductors whose sections do not have a sharp angle to avoid

the corona effect.

  3.- transformer according to claim 2, characterized in that the tubular conductors are of circular section

or rectangular with rounded edges.

4.- transformer according to any one of claims

  above, characterized in that said conductors are re-

continuously covered by an insulating sheath.

  5.- Transformer according to any one of the claims

  tions, characterized in that it consists of

multi-layer bearings wound so that the nominal voltage between two turns of successive layers does not exceed

  not the tension between two outer turns of the same layer.

  6.- Transformer according to any one of the claims

  tions, characterized in that the secondary is

hoeed on an isolated screen with ground potential in order to avoid

  aromas due to the roughness of the magnetic circuit.

  7.- Auto-transformer obtained from a transforma-

tor according to any one of the preceding claims, to

  using an external connection to the magnetic circuit for

  avoid the creation of a half-turn.

  8.- Transformer or auto-transformer according to one

  any one of the preceding claims, characterized in

  that it does not include a reverse winding, the potential of the refrigerant being brought to ground by a column of this fluid and in that the magnetic circuit, consisting of ferrites, is isolated from the high potential conductors, by a layer

of insulation, of the araldite type, and an air seal, the reinforcement

preferably placed on insulators.

i