DE1280398B - Variable transformer with locally polished adjusting winding - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

HOIf

German class: 21 d2- 53/02

Number: 1280 398

File number: P 12 80 398.4-32 (R 37000)

Filing date: January 17, 1964

Opening day: October 17, 1968

The invention relates to a variable transformer with a locally bare adjusting winding, those of two or more wound parallel to each other on the transformer core and at their ends consists of wires connected via resistors and on which a pantograph with a main brush grinds, the two auxiliary brushes of resistance contact material are adjacent in the grinding direction, the are electrically and mechanically connected to the main brush.

Variable transformers with multiple windings and a metal brush as a sliding contact can be operated with currents ten times higher than variable transformers with single-wire windings, in which carbon brushes are used. The width of the metal brush in the grinding direction must be less than (n-I) B, where B means the width of a wire of a winding, so that a short circuit in the winding is avoided, which consists of η wires parallel to each other on such a variable transformer are wrapped. If the width of the metal brush is less than (n- 1) B, there is no danger that the brush comes into contact with (n + 1) wires, which would cause a short circuit in the tap winding.

If the metal brush touches (n-1) or wires, it is known that resistors, as explained in the following paragraph, essentially prevent the formation of a short-circuit current. Despite the presence of a low short-circuit current, there are no tear-off sparks which could cause damage to the metal brush and the pick-off windings. However, a small spark is generated between adjacent turns at the moment the metal brush is lightly brought into contact with η or (n- 1) wires. These sparks can damage the surface of the metal brush or the pick-up coils. They always occur when the brush is moved towards the corresponding neighboring turn.

It is known that resistors are used to avoid such short-circuit currents (French patent 824 578), each of these resistors being between the corresponding Ends of the turns coming into contact with the sliding contact and the middle of one each of these resistors is connected to the input terminal. It is also known that the Sliding contact to avoid sparks from several pantographs, such as B. Brushes, Sanders or rollers. The mutual distance between these pantographs is so-called variable transformer with locally polished control winding

Applicant:
Keiichiro Ryu, Tokyo

Representative:

Dr. F. Zumstein,

Dipl.-Chem. Dr. rer. nat. E. Assmann and Dipl.-Chem. Dr. R. Koenigsberger, Patent Attorneys, 8000 Munich 2, Bräuhausstr. 4th

Named as inventor:
Keiichiro Ryu, Tokyo

ao selects that in all positions in which a pantograph stands on the insulating joint of two consecutive turns, the second and third Current collector on one turn of one or the other branch without touching an insulating joint fully applied, with a current divider choke being provided between the two current branches the center of which the current is fed to.

Variable transformers with such devices to avoid short-circuit currents or arcing have the disadvantage that the sliding contacts and the associated resistors a Complex construction requires that the distance adjustment of the pantographs is very precise and expensive construction requires that these distances by mechanical changes during prolonged operation on the sliding contact can not be maintained and that finally when translating the turn a small amount of sparking cannot be ruled out in relation to the winding.

According to the invention, these disadvantages are thereby eliminated in a variable transformer of the type mentioned at the outset eliminates the fact that the main brush is made of metal, is cylindrical and has a diameter, which is approximately equal to the diameter or the width of a winding wire and that the two Auxiliary brushes are combined into a cylinder ring which tightly encloses the cylindrical main brush. Such an arrangement of the cylindrical main brush with the auxiliary brushes surrounding it in a ring shape has the advantage that this compact design makes it easy to manage the inventive Sliding contact is possible and that a

809 627/939

mechanical change in the distance between the main and auxiliary brushes during a long period Operation remains excluded. The fact that in this design a material for the auxiliary brushes With a high electrical resistance can be used, resistors are advantageous or choke coils, which are connected between the main and auxiliary brushes, are unnecessary. Because of the simple production and the low material costs of the sliding contacts according to the invention there is a considerable reduction in price. Sparking is due to the exact translation of the turn to Winding switched off due to the exact and unchangeable brush dimensions.

With reference to the drawing, which represents an example embodiment of the invention, the variable transformer according to the invention explained in more detail. Fig. 1 shows a side and front view of a Brush;

Fig. 2 shows schematically a variable transformer ao with a sliding contact consisting of a brush according to FIG.

Fig. 1 shows the construction of a brush for a variable transformer with sliding contact. A is the side view and B is the plan of the brush. The current collector 1 connected via the line 4 has a main brush 2, the diameter of the main brush being as large as the width of a wire of a winding. An auxiliary brush in the form of a cylinder ring 3 made of a material with high resistance, e.g. B. coal od.

In the case of the variable transformer in FIG. 2, two winding wires α and b are wound parallel to one another on a transformer core 5, which results in the turns of a voltage regulator provided for the sliding contact. Resistors 8, 9 and 8 ', 9' are connected to both ends of the individual windings, thereby avoiding a short circuit, and the center points 10, 10 'are connected to terminals 6 and 7. The positions of the turns of the winding wires α and b provided for the sliding contact are indicated by a _v b _x .. .O _n , b _n. 11 and 12 are the output terminals of the variable transformer.

The sliding contact shown in FIG. 1 is used, in which the main brush 2 made of metal touches both winding wires O ₂ and b ₂ when the current collector 1 assumes the position shown below. If the current collector is then moved up or down in the illustration in the drawing, then touches the surface of the auxiliary brush, which is made of a material of high resistance, e.g. B. consists of silver-carbon, the winding wires b ₃ or a _v At the moment of contact, a spark would _{be expected due to the tension between the winding wires O 8} and a ₂ or b ₂ and O ₁ , but this spark is actually formed does not work because the contact is made through a material of high resistance, so that practically no damage is caused. Immediately before the current collector is moved in such a way that the main brush 2 only touches a winding wire Ct ₂ or b ₂ , the winding wire O ₂ or b ₂ is not yet free of the current collector, since the auxiliary brush made of silver-carbon that surrounds the main brush 2 , still touches both winding wires α and B. As a result, no sparking occurs, so that damage to the sliding contact surface of the winding and the sliding surface of the current collector are prevented, whereby the service life of the variable transformer is greatly increased.

The output current of the transformer according to the invention is taken from the main metal brush, and the short-circuit current of the short-circuited circuit formed by the main brush is avoided by the resistors preventing the short-circuit current. The sparking is caused by a metal brush that is surrounded with a material of high resistance avoided that the outer periphery of the auxiliary brush initially the successive turns of the Winding touches, whereupon the metal brush itself comes into contact with these windings. So the auxiliary brush gradually decreases part of the load current in stages, thereby adjusting the voltage he follows.

Claims (1)

Claim: Variable transformer with locally bare winding, which consists of two or more wires wound parallel to each other on the transformer core and connected at their ends via resistors and on which a current collector grinds with a main brush, which is adjacent in the grinding direction to two auxiliary brushes made of resistance contact material, which with the main brush are electrically and mechanically connected, characterized in that the main brush (2) is made of metal, is cylindrical and has a diameter which is approximately equal to the diameter or the width of a winding wire (a, b) and that the two auxiliary brushes are combined to form a cylinder ring (3) which tightly encloses the cylindrical main brush (2). Considered publications:
German Patent No. 633,948;
German utility model No. 1878 081;
Swiss Patent No. 14 734;
French patent specification No. 824 578. 1 sheet of drawings 809 627/939 10.65 © Bundesdiucketei Berlin