HK1202978B - Distribution transformer for voltage regulation of local distribution networks - Google Patents

Description

The invention relates to a distribution transformer for local power supply voltage regulation, which is often referred to in the technical literature as a local power supply transformer.

The standard voltage control in distribution systems is already at the medium voltage level. The increasing establishment of renewable energy generation possibilities has led to a major change in the conditions at the low voltage level - close to the consumer. On the one hand, it is noted that by supplying renewable energies at points close to the consumer, the power flows in the electricity networks change their direction depending on the input situation, i.e. depending on whether more electricity is taken or regeneratively fed.

The classical networks used to date have used distribution transformers for the connection of the medium and low voltage levels, which operate with a fixed transmission ratio. The short-term and quite significant voltage fluctuations described, which were not previously observed because of the absence of regenerative energy input, could not and cannot be compensated by such unregulated distribution transformers.

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DE 10 2008 064 487 A1 describes another design of such a adjustable distribution transformer, whereby a connected step-change device is based on one or more mechanical switches. Only when switching from one winding socket to another, the current is passed briefly through semiconductor switch elements to ensure uninterruption. This is also a hybrid switching device. i.e. a combination of mechanical and semiconductor switching technology.

The following is a further embodiment of a controllable distribution transformer, which is known from DE 10 2009 014 243 A1, whereby the primary side windings can be short-circuited by means of a switch matrix of power semiconductors or charged with a single-phase or counter-phase voltage by rapid switching, while maintaining the output voltage uninterrupted during switching operations.

WO 2010/144805 A1 also describes another adjustable distribution transformer that operates exclusively with semiconductor switching elements for switching, with the semiconductor switching elements and the complete solid-state step switcher located in a special pocket-like area on the top of the distribution transformer.

Each of these concepts has specific advantages and disadvantages. In the case of designs with semiconductor components, it should be noted that these are relatively temperature sensitive and, in general, cannot be placed directly in the insulating oil of the distribution transformer. This increases the design effort of such distribution transformers. The purpose of the invention is to specify a solution of a controllable distribution transformer which uses the vacuum technology proven in step switches, i.e. as switching elements or actuators to switch between the different winding starts on the control side of the distribution transformer vacuum tube.

Such vacuum switches have been proven for many years in the step switches offered by the applicant, in particular the VACUTAP® VV®, VACUTAP® VR® and VACUTAP® VM® types. However, due to their design and their large volume insulating cylinders used to cover the step switch, they are not suitable for use in transformers for space reasons. For functional reasons, such known step switches, even those of other manufacturers, which are fitted with vacuum technology, cannot be simply reduced to such a degree that they would be suitable for operation in upper stage transformers. However, such a reduction is obviously unsuccessful, for example, because the maximum output of the known step transformer is driven by a continuous drive of the step transformers. The first step of the transformers is usually to be carried out by a mechanical force or a rotary load. The first step of the transformers is to be fitted with a load-free load-bearing system, and the first step is to be fitted with a load-free load-bearing system.

The general idea of the invention is to provide for an adjustable distribution transformer with a step control device in which both the selector contact unit and the switches for continuous load switching can be operated by means of a common motor drive without an energy storage intermediate circuit.

In a preferred embodiment, this is achieved by transferring a rotational motion produced by a motor drive via a drive module to a spindle in contact with a spindle matrix provided for a central slide, so that a longitudinal displacement of the central slide along guide rods is produced, while the remaining slides are connected to the central slide via a longitudinally sliding slide on the second side of a support plate, also on the central slide, and are in direct contact with the mechanical slide-coupled guide frame, so that the remaining slides are in turn connected to the central slide-coupled guide frame, which is connected to the central slide-coupled guide frame, while the mechanical slide-coupled guide frame is connected to the central slide-coupled guide frame, which is connected to the central slide-coupled guide frame, thus simultaneously controlling both the load-carrying unit and the vacuum-controller's voltage.

In another embodiment of the invention, the distribution transformer has a gear module attached to the bottom of its cover which interacts with the motor drive located on the opposite outside of the cover. The gear module has a flange-like seal module directly located on the bottom of the cover and soluble connected to the motor drive, in particular screwed, to which the gear module is also attached the entire step control of the transformer. This gives the gear module the function both of holding the step control and of sealing the transformer by means of the diode module against the outer control of the transformer.

Another preferred embodiment of the invention is a support plate made of a dielectric material, in particular a plastic, on which the selector contact unit is placed on one side and the switches for continuous switching on the other side, so that the support plate provides the ground clearance necessary for the step control device.

In another embodiment of the invention, the at least one contact unit is moved during a switch along two conductors, which are arranged in essentially parallel, ensuring a linear conduction of at least one contact unit and are held by several cross-sections arranged on the support plate.

In another embodiment of the invention, the movable contact points are each incorporated into a contact holder and interact with fixed contact points placed on the support plate, so that the individual fixed contact points can be switched along the guide rod by a longitudinal displacement of the movable contact points including the slide, i.e. the contact unit. By moving the contact unit back and/or forth, the individual fixed contact points are switched and thus the control area of the step control device passes through. In a particularly simple way, the several crossings at which the control poles are held form a mechanical connection for the control area, so that the control area is also mechanically limited.

In another embodiment, the continuous-shift actuators are placed directly on the respective slide of the corresponding switchgear unit, and in this embodiment, the continuous-shift actuators and the switchgear unit are operated by a common motor drive without an energy storage intermediate, by means of a transfer gear, which drives a central winding spindle which in turn converts the rotation into a longitudinal shift of the switchgear, so that both the movable switchgear contacts and the switching contacts on the switchgear unit can be operated under the direction of the step-regulator transformer.

In another embodiment of the invention, the motor drive is driven by both a threaded spindle which in turn is connected to the switchgear unit and a camshaft which operates the switches for continuous switching, which makes it particularly advantageous to operate the switchgear unit easily independently of the switches for continuous switching of the step control device of the distribution transformer.

The following is a more detailed description of the invention and its advantages, by reference to the accompanying drawings:Fig. 1a schematic representation of a distribution transformer according to the invention with step-control device;Fig. 1a schematic perspective view of the distribution transformer according to the invention;Fig. 1a schematic diagram of a distribution transformer according to the invention with step-control device;Fig. 2a second side view from the first side of the distribution transformer according to Fig. 1, where the two side view figures are arranged;Fig. 2a second side view from the first side of the distribution transformer, where the two side view figures are arranged;Fig. 2a second side view from the distribution transformer, which provides a more detailed perspective of the distribution transformer, which provides a more detailed perspective of the distribution transformer.Fig. 7a shows the dimensions of a load-contactor;Fig. 4a shows the dimensions of a load-contactor;Fig. 7a shows the dimensions of a first side view; 6a shows the dimensions of a second side view; 7a shows further details of a second side view; 6a shows the dimensions of a second side view; 7a shows the dimensions of a second side view; 7a shows further details of the first side view; 6a shows the first side view of a transformer; 7a further details of the first side view of the transformer; 7a further details of the first side view of the transformer; 6a further details of the transformer; 7a further details of the first side view of the transformer; 7a further details of the transformer.

Figures 1a, 1b and 1c show a step control device 1 in conjunction with a distribution transformer 40 according to the invention, which is located directly below a transformer cover 2 of the distribution transformer 40. Such a control transformer 40 comprises a transformer boiler filled with insulating oil in which at least one winding 42.1...42.3 is arranged at an iron jock 41. This winding 42.1...42.3 is divided in a control transformer 40 in conjunction with a main winding 43 and a control transformer 44, where several winding winding winding winding 45.1...45.5 are connected to form the entire power supply area. The winding winding of the control transformer 44 is connected to the power supply area. The control transformer 1 is designed to operate in a direction opposite to the direction of the power supply. For example, the control transformer 1 is designed to be mounted on a motor 2 and the control transformer 3 is mounted on a motor 2 in such a way that the power supply is connected to the power supply area. The control transformer 1 is mounted on a control transformer 3 in such a way that the power supply is connected to the power supply area.

Figures 2a and 2b show the step control unit 1 of the distribution transformer according to the invention in two different perspective side views. Mechanically connected to the transmission module 3 is a support plate 6 of dielectric material to which the individual components of the step control unit 1 can be attached. The support plate 6 is made of electrically insulating material and is designed to accommodate all the essential components of the step control unit 1. Figure 2a shows the first side of the step control line 1 of the distribution transformer according to the invention, where the orientation of the components of the at least one selector contact unit 7.1, 7.2 and 7.3 is fixed to the support plate 6a.Each of the connecting contacts 7.1 to 7.3 comprises several adjustable fixed connecting contacts 8.1 to 8.5, electrically connected to the winding connections of the transformer's Rule 44 winding, a connecting rail 9 connected to a load line LA and a connecting bearing 10.1 to 10.3 with two spring-loaded, movable connecting wavelengths 11.1 and 11.2 each.The second fixed contact, for example the fixed contact 8.2, adjacent to the first fixed contact, is switched on as a stationary operating position of the step control unit 1. This allows, according to the rectifier switch principle, for 5 fixed contacts 8.1...8.5 shown here nine stationary operating positions, while for a step control unit 1 after the resistance fast-shift zipper, in which no means are allowed, there are only 5 operational switches.12.3 on two parallel plates, on which the support plate 6 is fixed by means of several cross-sections 13.1... 13.3, the guide rods 14.1 and 14.2, so that the individual fixed contact points 8.1 ... 8.5 can be charged by a longitudinal displacement of the movable contacts 11.1 ... 11.3 including the slide 12.1 .... 12.3 along the guide rods 14.1 ... 14.2.The various cross-sections 13.1 ... 13.3 on which the guide bars 14.1 and 14.2 are held also form a mechanical link for the longitudinally travelled guide bars 10.1 ... 10.3 ... 12.3 ... 10.3 ... 12.3 ... 10.3 ... 12.3 ... 12.3 ... 10.3 ... 12.3 ... 12.3 ... 12.3 ... 10.3 ... 12.3 ... 12.3 ... 10.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 10.3 ... 10.3 ... 12.3 ... 12.3 ... 12.3 ... 12.3 ... 10.3 ... 10.3 ... 10.3 ... 10.3 ... 12.3 ... 12.3 ... 12.3 ... 10.3 ... 10.3 ... 10.3 ... 10.3 ... 10.3 ... 10.3 ... 12.3 ... 12.3 ... 12.3 ... 10.3 ... 10.3 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

Figure 2b shows the second side of the support plate 6 of the step control device 1 of the distribution transformer according to the invention, on which the switches are arranged for continuous switching. The switches for continuous switching in the embodiment of Figure 2b are vacuum switches 19.1 to 19.6, with two vacuum switches 19.1 and 19.2 and 19.3 and 19.4 and 19.5 and 19.6 respectively, each oriented in a phase 1 direction of the step control and interacting with a corresponding selector contact unit 7.1 to 7.3.Each of the vacuum tubes 19.1 to 19.6 comprises a movable switch contact 20.1 to 20.6 which is articulated on the other side of the support plate 6 with a coupling 21.1 to 21.6 and a control lever 22.1 to 22.6. At the joint connection between the corresponding coupling 21.1 to 21.6 and the control lever 22.1 to 22.6, on the side facing the support plate 6 there is a rotating coil 23.1 to 23.6 which partially extends along the contact lock on the top 24 of the guide frame 17. The top 24 of the guide frame 17 has a profile in the form of nochal ligaments so that the vacuum drives on 19.1 to 17.1 rotate on a roll of lead, depending on the profile of the guide frame 17i.e. can be opened or closed.

Figure 3 shows a simplified detailed view of the mechanical coupling of the slides 12.1 to 12.3 with the guide frame 17. The gear module 3 is shown, which transmits a rotation to the spindle 15 via gears not shown here, which in turn transmits the rotation to a spindle nut 16 provided for in the middle slide 12.2 so that the rotation of the spindle 15 is converted into a slide motion of the middle slide 12.2 along the guide bars 14.1 and 14.2.

Figures 4a and 4b show and illustrate in two different perspectives a further detailed view of the switchgear 7.1 of a phase 1 step control unit; the switchgear 7.2 and 7.3 are identical in construction, so the following explanations also apply to these switchgear 7.2 and 7.3. The fixed switchgear 8.1 to 8.5 are placed on a plastic contact 25.1 such as a screw connection shown here. On the support plate 6, the switchgear 25.1 is attached by two spacers 27.1 to 27.2 each, which are not to be used as a connection to a designated overclocking or overclocking switch or to a generated overclocking switch.In addition, the contact strip 25.1 has a control panel 26.1 on its longitudinal side, on which several pins 28.1...28.4 are arranged on either side to move vertically the spring-loaded voter contacts 11.1 and 11.2 of the corresponding voter contact unit 7.1 when the corresponding slide 7.1 is moved along the length of the slide 12.1 by means of the pins 28.1...28.4 provided for in the control panel 26.1, depending on the contour of the several pins 28.1...28.4.The first is the first, where the power supply is switched on, and the second is the first, where the power supply is switched on again, where the moving switch 11.1 and 11.2 are placed on two adjacent fixed switches 8.1 ... 8.5 according to the reactor switching principle, while the next fixed switch is switched on according to the resistance-fast switching principle.

Figure 5 shows the contact strip 25.1... 25.3 with the control backing 26.1... 26.3 and the several pins 28.1... 28.4 in each case in a detailed view, by means of which the corresponding movable switchgear 11.1 and 11.2 or 11.3 and 11.4 or 11.5 and 11.6 of each switchgear 7.1 ... 7.3 move vertically during a switch operation, depending on the contour of the pins 28.1 ... 28.4.

In the built-in state of the step control unit 1 in the distribution transformer according to the invention, the movable switchgear contacts 20.1 to 20.6 of the vacuum switching tubes 19.1 to 19.6 are electrically connected to the spacer holders 27.1 to 27.2 corresponding to the respective phase and thus ultimately to the corresponding switching thresholds or switching resistors, while the corresponding fixed contact 18.1 to 18.6 of the corresponding vacuum switching tube 19.1 to 19.6 is electrically connected to the contact rail 9 of the corresponding phase.

In Figures 6a and 6b, a further embodiment of a step control device 1 for a distribution transformer according to the invention is shown. The description of the figures merely explains the differences with the previous figures, addressing identical components with the same reference marks as in Figures 1 to 5. In this embodiment of the step control device 1, the switching devices for continuous switching, i.e. the switching tubes 19.1 to 19.6, are located directly on the corresponding sliders 12.1 to 12.3 of the respective switchgear 7.1 to 7.3 and are designed along the entire length of the wire spindle 15. A switchgear 7.1 to 7.3 is not feasible in this embodiment, but each switchgear has its own configuration, which is not feasible in this embodiment.Spindle nut 16 is arranged in the corresponding slide 12.1 ... 12.3 so that the selector contact units 7.1 ... 7.3 are thus mounted in synchronous motion along the winding spindle 15. The winding spindle 15 is composed of several parts and has a clutch tube 28.1 ... 28.2 formed of electrically insulating material between each of the corresponding parts. In addition, an angle gear 29 is provided to transmit the rotational motion of the motor drive 3 to the winding spindle 15. Between the motor drive 3 and the angle gear 29 is an insulating shaft 30 of the gliding material, which directs the rotational motion of the motor drive 3 into the angle of a fixed contact.The movable switch contacts 20.1...20.6 of the vacuum switch tubes 19.1...19.6 are connected by a mechanical link with a tilt-pipe arrangement 32.1...32.6 which each have a role 33.1...33.6. In the built-in state of the step-control line 1, the movable switch 20.1...20.6 of the vacuum switch tubes 19.1....19.6 are connected electrically with the movable switch contacts 11.1...11.2 of the associated electrical phase. The corresponding tilt-pipe contacts 20.1...33.3 are connected to the corresponding tilt-pipe arrangement 32.1...33.3 of the switch, so that the respective switch 20.1...20.6 of the vacuum switch tubes 19.1....19.6 moves along a profile of the switch, so that the corresponding tilt-pipe arrangement 19.1...1...12.3 is moved away from the corresponding rolling roller.The fixed connectors 8.1 to 8.5, of which only the fixed connectors 8.3 to 8.5 are shown in this figure, are located directly on the support plate 6 and, on the opposite side, not shown here, the support plate 6 is electrically connected to the corresponding winding contacts of the control winding of the distributor.

In Figures 7a and 7b, a further embodiment of a step control device 1 for a distribution transformer is shown. Again, this figure describes the differences from the previous figures, referring to identical components with the same reference marks as in Figures 1 to 5. In Figures 7a and 7b, the motor drive 3 drives both a threaded spindle 15 which is in turn mechanically connected to each of the selector contacts 7.1 to 7.3 and a camshaft 35 by means of which the slide means are uninterrupted, i.e. the vacuum switches 19.1 to 19.1 are connected. Figures 6 and 15 are shown here with the total of the threaded spindle 6 and the total of the threaded spindle 6 being disconnected in each of the 12 sections.The other switch connector 7.1...7.3 is constructed in the same way as the switch connector 7.1...7.3 described in Figures 1 to 5. To operate the rotary valve tubes 19.1...19.6 each movable switch connector 20.1....20.6 is mechanically coupled to a lever 36.1...36.6 which is located on the corresponding switch connectors 20.1...36.6 and is located on the axis of the controller 35.1...37.6 which is not connected to the controller 37.1...37.6 which is connected to the controller 20.1...36.6 by a vacuum corresponding to the last movement of the controller 36.1...37.6 and corresponding to the last movement of the controller 36.6...37.Depending on the switching sequence used for the step control device 1, several control knots 37.1 to 37.6 are provided for each vacuum switch 19.1 to 19.6 at the circumference of the camshaft 35.

In summary, the step control unit 1 can be used both on the reactor switch and on the resistance-fast switch principle, depending on the switch principle used, whereas the five fixed switch contacts 8.1 to 8.5 shown here allow 9 stationary positions for the reactor switch, the step control unit 1 for the resistance-fast switch principle only allows 5 stationary positions.

List of reference marks

The following is a list of the components of the system: 1. the power supply, 2. the power supply, 3. the power supply, 3. the power supply, 4. the power supply, 4. the power supply, 4. the power supply, 4. the power supply, 5. the power supply, 5. the power supply, 5. the power supply, 5. the power supply, 5. the power supply, 5. the power supply, 5. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 6. the power supply, 7. the power supply, 7. the power supply, 7. the power supply, 7. the power supply, 7. the power supply, 7. the power supply, 7. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the power supply, 8. the 7. the power supply, 8. the 7. the 7. the power supply, 8. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 7. the 8. the 8. the 8. the 8. the 8. the 8. the 8. the 8. the 8. the 8. the 8. the 8. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the 9. the

Claims (17)

1. Distributing transformer (40) for voltage regulation of local mains, comprising

   - a main winding (43) and a regulating winding (44) with a plurality of winding taps,

   - a step regulating device (1) for uninterrupted switching over between different winding taps of the regulating winding (44) of the distributing transformer (40),

   - a transmission module (3),

   - a motor drive (4) for introducing a drive movement into the step regulating device (1) by way of the transmission module (3) and

   - two vacuum interrupters (19.1, 19.2 or 19.3, 19.4 or 19.5, 19.6) for uninterrupted switching over for each phase,

   wherein

   - at least one selector contact (7.1 ... 7.3) with a respective plurality of fixed selector contacts (8.1 ... 8.5) respectively electrically connected with the individual winding taps is arranged along a line,

   - the fixed selector contacts (8.1 ... 8.5) are actuable by two longitudinally displaceable movable selector contacts (11.1, 11.2),

   - the entire step regulating device (1) is arranged by means of the transmission module (3) at the underside of a transformer cover (2) and

   - the at least one selector contact unit (7.1 ... 7.3) and the vacuum interrupters (19.1 ... 19.6) are so directly actuable by means of the common motor drive (4) that the introduction of the drive movement of the motor drive (4) into the at least one selector contact unit (7.1 ... 7.3) and the vacuum interrupters (19.1 ... 19.6) takes place without interposition of a mechanical energy store.
2. Distributing transformer according to the preceding claim, wherein

   - a rotational movement generated by the motor drive (4) is transmissible by means of a transmission module (3) to a threaded spindle (15) engaged with a spindle nut provided at a centre slide carriage (12.2) so that a longitudinal displacement of the centre slide carriage (12.2) along guide rods (14.1, 14.2) can thereby be produced,

   - the remaining slide carriages (12.1, 12.3) are operatively connected with the centre slide carriage (12.2) by way of a similarly longitudinally displaceable guide link, which is mechanically coupled with the centre slide carriage (12.2), so that the remaining slide carriages (12.1, 12.3) in turn are so mechanically coupled with the centre slide carriage (12.2) by way of the guide link (17) that not only the selector contact units (7.1 ... 7.3), but also the vacuum interrupters (19.1 ... 19.6) are thereby simultaneously actuable.
3. Distributing transformer according to any one of the preceding claims, wherein

   - the transmission module (3) comprises a flange-like sealing module (5).
4. Distributing transformer according to any one of the preceding claims, wherein

   - a support plate (6) of a dielectric material, at the first side of which the at least one selector contact unit (7.1 ... 7.3) and at the second side of which the vacuum interrupters (19.1 ... 19.6) are arranged, is provided.
5. Distributing transformer according to any one of claims 2 to 4, wherein

   - the at least one selector contact unit (7.1 ... 7.3) comprises a respective slide carriage (12.1 ... 12.3), a respective contact carrier (10.1 ... 10.3) and respective movable selector contacts (11.1, 11.2) which co-operate with at least one fixed selector contact (8.1 ... 8.5).
6. Distributing transformer according to any one of claims 2 to 5, wherein

   - the slide carriage (12.1 ... 12.3) is received by two parallelly arranged guide rods (14.1, 14.2) which are in turn arranged at the support plate by means of cross members (13.1 ... 13.3).
7. Distributing transformer according to any one of claims 4 to 6, wherein

   - the movable selector contacts (11.1, 11.2) are each received in a contact carrier (10.1 ... 10.3) and co-operate with fixed selector contacts (8.1 ... 8.5) arranged at the support plate (6).
8. Distributing transformer according to any one of claims 2 to 7, wherein

   - the at least one selector contact unit (7.1 ... 7.3) is arranged to be so displaceable along the guide rods (14.1, 14.2) by means of the respective slide carriage (12.1 ... 12.3) that it is thereby possible to run through the regulating range of the step regulating device (1).
9. Distributing transformer according to any one of claims 2 to 5, 7 or 8 and claim 6, wherein

   - the plurality of cross-members (13.1, 13.3) forms a mechanical abutment for the at least one selector contact unit (7.1 ... 7.3), which is displaceable along the guide rods (14.1, 14.2), in such a way that the regulating range of the step regulating device (1) is mechanically limited.
10. Distributing transformer according to any one of the preceding claims, wherein

    - the movable selector contacts (11.1, 11.2) of a phase in each stationary operational setting connect at least one fixed selector contact (8.1 ... 8.5) of the same phase of the step regulating device (1).
11. Distributing transformer according to any one of the preceding claims, wherein

    - in each instance two movable selector contacts (11.1, 11.2) are received in a contact carrier (10.1 ... 10.3) to be resiliently mounted.
12. Distributing transformer according to any one of claims 4 to 11, wherein

    - the movable switch contact (20.1 ... 20.6) of the corresponding vacuum interrupter (19.1 ... 19.6) is respectively pivotably and mechanically operatively connected with a coupling element (21.1 ... 21.6) and a control lever (22.1 ... 22.6), and provided at the pivotable connection between the corresponding coupling element (21.1 ... 21.6) and the control lever (22.1 ... 22.6) on the side facing the support plate (6) is a roller (23.1 ... 23.6) which rolls along a profiled upper side (24) of the guide link (17) under partially maintained contact so that the respective vacuum interrupter (19.1 ... 19.6) is connectible by a longitudinal displacement of the guide link (17) in dependence on the profiling of the upper side (24) thereof.
13. Distributing transformer according to any one of claims 4 to 12, wherein

    - the fixed selector contacts (8.1 ... 8.5) are arranged at a contact strip (25.1 ... 25.3), which contact strips are in turn fastened to the carrier plate (6) by means of respective spacers (27.1 ... 27.3).
14. Distributing transformer according to any one of the preceding claims, wherein

    - the contact strip (25.1 ... 25.3) has at its longitudinal side a control link (26.1 ... 26.3) at which several lobes are arranged on both sides.
15. Distributing transformer according to any one of the preceding claims, wherein

    - the profile of the lobes is so dimensioned that the movable selector contacts (11.1, 11.2) of the corresponding selector contact unit (7.1 ... 7.3) between two adjacent fixed selector contacts (8.1 ... 8.5) lift off the currently connected fixed selector contact, since the movable selector contacts (11.1, 11.2) again connect the next fixed selector contact after switching over has been completed.
16. Distributing transformer according to any one of the preceding claims and claim 2, wherein

    - two respective vacuum interrupters (19.1 and 19.2, 19.3 and 19.4, 19.5 and 19.6) per phase are directly arranged at the corresponding slide carriage (12.1 ... 12.3) of the respective selector contact unit (7.1 ... 7.3),

    - the motor drive (4) drives a central threaded spindle (15) by means of an angle transmission (29)

    - each slide carriage (12.1 ... 12.3) has a separate spindle nut (16) and

    - the threaded spindle (15) co-operates with the spindle nut (16) of each slide carriage (12.1 ... 12.3) and the rotational movement can be converted into a synchronous longitudinal displacement of the plurality of slide carriages (12.1 ... 12.3) in such a manner that not only the movable selector contacts (11.1, 11.2), but also the vacuum interrupters (19.1 ... 19.6) are thereby actuable.
17. Distributing transformer according to any one of the preceding claims, wherein

    - the motor drive (4) drives not only a threaded spindle (15), which in turn is operatively connected with the selector contact unit (7.1 ... 7.3), but also a camshaft (35), by way of which the vacuum interrupters (19.1 ... 19.6) are actuable, in such a manner that both the movable switching contacts (11.1, 11.2) and the vacuum interrupters (19.1 ... 19.6) are thereby actuable.