DE9308424U1 - Step selector with multiple coarse selector for step switches - Google Patents

Description

362aMe/Gl

Tap selector with multiple coarse selector for tap switches

The innovation concerns a tap selector with multiple coarse selectors for tap switches on tap transformers for a particularly high number of voltage steps.

In the case of tapped transformers, it has long been known to provide a coarse step on the main winding, to which one or the other end of the fine step winding can be selectively connected using a coarse selector. In the case of transformers for special purposes, such large setting ranges are sometimes required, or such a fine-step voltage setting with a large number of operating positions is required, that this can only be achieved using a multiple coarse selector in conjunction with several coarse steps on the main winding of the tapped transformer.

A step switch is already known from the applicant's publication "Technical data - step switch type M", imprint: TD 50/85 de-0390/500, whose step selector has a fine selector with selector contacts arranged in two levels for each phase and a multiple coarse selector, which in turn consists of two conventional simple coarse selectors. The two coarse selectors are mounted on both sides of the fine selector. To operate the selector, two Geneva wheels, driven jointly by a Geneva driver, are arranged above, with each Geneva wheel operating one fine selector level for each phase and one of the two coarse selectors on the side.

This means, for example, that 107 operating positions can be achieved with a five-stage coarse winding and a fine-stage winding with 18 taps.

The disadvantage of this well-known step selector with multiple coarse selectors is that the arrangement on both sides results in a

very large selector with a housing that is oval in cross-section or otherwise deviates from a circular shape, which requires considerable space and is difficult to accommodate in the transformer tank and where the mechanical connection to the diverter switch is also problematic.

Another disadvantage is the large number of special components required, including the special selector housing with a cross-section that deviates from the circular shape, which must be kept in stock for a version with multiple coarse selectors, which is one of the special versions and is usually only manufactured on special customer request.

In the case of the known selector structure as a cage made of laminated paper or GRP rods, this means that a cage that differs from the cylindrical shape with special base and head sections is required.

In the case of tap selectors with closed insulating cylinders as housings, it must also be taken into account that these insulating housings, which are usually made of GRP, can only be manufactured with reasonable effort using winding technology as cylindrical, i.e. rotationally symmetrical parts; the different cross-section required according to the state of the art makes production of such selectors complex and expensive.

The aim of the innovation is therefore to create a space-saving step selector of the type mentioned, which consists of as few special components as possible, but rather can be constructed in a modular manner from the gear components required for the fine selector anyway and which allows a selector housing with a circular cross-section.

This object is achieved by a step selector with the features of the first claim; the subclaims contain particularly advantageous developments of the invention.

The new step selector therefore consists of two separate housings; one housing accommodates the

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Fine selector; the other housing contains the complete multiple coarse selector.

A frame made of hard paper or GRP rods or a closed insulating cylinder can be used as the housing. The new multiple coarse selector has, in addition to the circular cross-section of the housing, the particular advantage that the coarse selector uses essentially the same drive parts as the fine selector, in particular the same Geneva wheels with the same number of parts can be used, corresponding to the number of fine selector stages.

Furthermore, the new tap selector with its two cylindrical housings allows for more flexible installation in the transformer, since the two housings can also be arranged far apart from each other, whereby the distance between the housings can be varied depending on the respective installation conditions.

The innovation will be explained in more detail below using examples.

Show it:

Fig. 1 the new multiple coarse selector of the

Step selector alone in schematic sectional view
from the beginning

Fig. 2 also shows the drive schematically in
perspective representation

Fig. 3 the complete step selector, consisting of
Fine selector housing and multiple coarse selector housing in basic arrangement

The entire multiple coarse selector consists of a drive head 1 and a cylindrical housing 2, which, as already explained, can consist of insulating rods or a cylinder.

In the wall of the housing 2 there are the fixed coarse selector contacts 2.1, 2.3,...,2.In in a horizontal plane I as well as the fixed coarse selector contacts 2.2, 2.4,...,2.m+1 in a further horizontal plane II.

The drive head 1 contains a gear, explained in more detail below, which converts the rotary motion of a drive shaft 3 coming from the motor drive 17 into a rotary motion of two concentrically mounted Geneva wheels 4, 5.

These Geneva wheels 4, 5 are connected to concentrically mounted, independently rotating drive shafts 6, 7, each of which carries a rotating coarse selector contact 8, 9. The coarse selector contact 8 actuates the fixed coarse selector contacts 2.1, 2.3,...,2.m of the first horizontal level I and the coarse selector contact 9 actuates the fixed coarse selector contacts 2.2, 2.4,...,2.m+1 of the second horizontal level II. The movable coarse selector contacts are designed in a manner known per se as contact bridges, for example according to DE 39 28 359, which each connect a fixed contact in the wall of the housing 2 to a concentric electrically conductive discharge ring 10, 11, which is each connected to a contact discharge (not shown in more detail).

The gear in the drive head 1 consists of a Geneva driver 12, which is operated via a deflection gear directly by the drive shaft 3 coming from the motor drive 17. This Geneva driver 12 has an upper driver cam 12.1 and a lower driver cam 12.2 on both sides, offset by 180° when viewed horizontally. The upper driver cam 12.1 engages in notches in the upper Geneva wheel 4, and the lower driver cam 12.2 engages in those in the lower Geneva wheel 5.

The upper Geneva wheel 4 in turn has an upper Geneva cam 4.1, the lower Geneva wheel 5 a lower Geneva cam 5.1, which each engage in an upper slotted wheel 13 or a lower slotted wheel 14. The rotational movement of the upper slotted wheel 13 is transmitted to the

the inner drive shaft 6, that of the lower slotted wheel 14 via a lower gear pair 16.1, 16.2 to the outer drive shaft 7.

The mode of action is as follows:

At each switchover, the motor drive 17 (not shown in detail) triggers a rotary movement of a motor drive shaft 18,
which is transmitted to a drive shaft 19 of the fine selector (FW) as well as to the drive shaft 3 of the multiple coarse selector (GW) and there generates a rotation of the Geneva driver 12 by 180° in each case. With each switchover, the upper driver cam 12.1 alternately engages the upper Geneva wheel 4 or the lower driver cam 12.2 engages the lower Geneva wheel 5 and rotates the respective Geneva wheel by an angle that depends on their division. This division results from the number of fine selector contacts in each actuation level of the fine selector (FW).
After a full revolution of each Geneva wheel 4, 5, ie after the complete passage of all fine selector contacts, either the upper Geneva cam 4.1 engages the upper slotted wheel 13 or the lower Geneva cam 5.1 engages the lower slotted wheel 14 and rotates it by a certain angle.

This rotary motion is then transmitted to the inner drive shaft 6 and the outer drive shaft 7 by the upper gear pair 15.1, 15.2 and the lower gear pair 16.1, 16.2. The inner drive shaft 6 thus switches the coarse selector contacts in level II, and the outer drive shaft 7 switches those in the horizontal level I.

It has already been explained that the Geneva wheels 4, 5 have the same number of parts as those for driving the separate fine selector. However, while in the fine selector the Geneva wheels alternately switch a contact level of the fine selector with each switching, in the multiple coarse selector they run idle; only after a complete rotation of 360° is a switching movement for the coarse selector generated via the respective Geneva cam.

Claims (1)

-6- Protection claims L. Tap selector for tap changers on tap transformers for a high number of voltage steps, consisting of a fine selector with fixed selector contacts arranged in a circle in two levels in the wall of a housing for each phase, which can be swept over by contact bridges guided on concentric drive shafts, whereby the drive shafts can be operated individually by a Geneva gear connected to the tap changer drive, further consisting of a multiple coarse selector which has further fixed contacts which are each connected to an output of a coarse step of the main winding of the tap transformer and can be swept over by further movable contact bridges, characterized in that that the fine selector (FW) and coarse selector (GW) are designed as separate assemblies within separate housings, such that the fixed coarse selector contacts (2.1 ... 2.m+l) are arranged in the wall of a further housing (2) and the further movable contact bridges (8, 9) which pass over them are connected to further concentric drive shafts (6, I) ₁ which run vertically centrically through the further housing (2) and that the drive shafts (6, 7) can be actuated by a further Geneva gear which is connected to the step switch drive (17). Step selector according to claim 1,
characterized, that the further Geneva gear consists of a Geneva driver (12) which can be driven by a drive shaft (3) and which, in a manner known per se, has an upper driver cam (12.1) and a lower driver cam (12.2) offset by 180°, whereby the upper driver cam (12.1) engages in an upper Geneva wheel (4) and the lower driver cam (12.2) engages in a lower Geneva wheel (5), that on each Geneva wheel (4, 5) there is a Geneva cam (4.1, 5.1) which, after a complete rotation of the associated Geneva wheel (4, 5), engages in an upper slotted wheel <13) or a lower slotted wheel (14) and that each slotted wheel (13, 14) is connected to one of the further concentric drive shafts (6, 7). 3. Step selector according to claim 1 or 2,
characterized, that the drive shaft (3) of the further Geneva gear, which operates the multiple coarse selector (GW) and the drive shaft (19) of the Geneva gear, which operates the fine selector (FW), have an equal transmission ratio of the rotary movement of the motor drive (17). 4. Step selector according to one of the preceding claims, characterized in that the Geneva wheels of the Geneva drive operating the fine selector (FW) and the Geneva wheels (4, 5) of the further Geneva drive operating the multiple coarse selector (GW) have the same number of parts. 5. Step selector according to one of the preceding claims, characterized in that the number of notches of the upper slotted wheel (13) and the lower slotted wheel (14) corresponds to the number of fixed coarse selector contacts arranged in a circle in a horizontal plane.