Method for carrying out a switchover of at least one switching means for equipment, and drive system for at least one switching means for equipment

Abstract

The invention relates to a method for carrying out a switchover of equipment (20). The equipment (20) comprises at least one first switching means (17), which can be an on-load tap changer, and / or at least one second switching means (18), which can be a two-way commutator (18). The invention additionally relates to a drive system (3) for at least the first and the second switching means (17, 18) of equipment (20). Each first switching means (17) and each second switching means (18) is paired with a dedicated motor (12, 13) which is connected to the first switching means (17) and each second switching means (18) via a driveshaft (16). At least one parameter can be ascertained for the first switching means (17) and each second switching means (18) by a respective feedback system (6, 7) paired with the first motor (12) and each second motor (13). The ascertained parameters determine the locking conditions for the first switching means (17) and the second switching means (18).

Description

[0001] The invention relates to a method for performing a switching operation of at least one switching device of an operating device.

[0002] Furthermore, the invention relates to a drive system for at least one switching device of an operating device.

[0003] Document WO 2012 / 135209 A1 discloses a method for performing a switching operation of at least one switch using at least one operating device, according to the preamble of claim 1.

[0004] German patent application DE 10 2014 110 732 A1 discloses a load tap changer with a motor drive for switching between winding taps of a tap changer. A drive shaft is driven by the motor drive. The rotary motion of the motor drive is provided via two switchable coupling devices: one for a drive shaft associated with the selector and the other for a load tap changer. The selector and the load tap changer can be configured to be switchable independently of the initial rotary motion of the motor drive.

[0005] Voltage regulation in power transmission and distribution networks requires the installation of different types of switches in transformers. Various factors influence the operation of the transformer and, consequently, the switches. For example, in transformers with two integrated tap changers, the operation of both must be coordinated. This is achieved using a rigid linkage between the two tap changers, driven by a common motor. Incorrect coupling of the linkage can cause malfunctions during operation, which in extreme cases can have serious technical and economic consequences.

[0006] It is therefore an object of the present invention to provide a method for performing a switching operation of at least one switching device of an operating device, which increases the safety and reliability of the switching device and the operating device.

[0007] This problem is solved by a method for performing a switching of a switching device of an operating device, comprising the features of claim 1.

[0008] Another task is to specify an improved concept for a drive system of a switching device, which increases the safety of the switching device and the operating equipment.

[0009] Another object of the invention is to provide a drive system for at least one switching device of an operating device, which increases the safety and reliability of the switching device and the operating device during the switching process.

[0010] The above problem is solved by a drive system for at least one switching device of an operating device, comprising the features of claim 9.

[0011] The inventive method for performing a switching operation of at least one switching element assigned to a device is characterized in that a control unit or control device receives a switching signal. The control unit selects at least one of the switching elements for switching. This selection is made based on the switching signal. At least one parameter is queried by the control unit from a feedback system. A feedback system can be assigned to a motor of each switching element. The switching operation is performed with the selected switching element by means of a motor connected to the respective switching element via a drive shaft. The switching operation only takes place when the corresponding locking condition for the selected switching element is met.

[0012] The switching signal can be generated, for example, by a voltage regulator, manual input, or in any other way. The voltage regulator monitors voltage fluctuations in the network. As needed, a signal is sent to the control unit, so that the voltage is adjusted accordingly when the switching device is actuated.

[0013] The method according to the invention is based on the idea that, before a switching device in an operating device, such as a transformer, is actuated or switched and a switching operation is carried out, an interlock condition is checked in a control unit or control device. A parameter is queried for this check. If the interlock condition is met by the queried parameter, the switching operation takes place.

[0014] In a first possible embodiment of the method according to the invention, a load tap changer is assigned to the transformer as a first switching element and a double reversing unit as a second switching element. For the switching operation, a power section assigned to the transformer is controlled by the control unit to actuate the load tap changer or the load tap changer and the double reversing unit. Depending on the switching operation, a first motor connected to the load tap changer via a drive shaft and / or a second motor connected to the double reversing unit via a drive shaft are actuated.

[0015] According to another possible embodiment of the method according to the invention, three on-load tap changers are assigned to the transformer as a first switching element. For the switching operation, a power unit assigned to the transformer is controlled by the control unit to actuate one of the three on-load tap changers. Depending on the switching operation, the power unit actuates a first motor of each on-load tap changer via a drive shaft connected to the on-load tap changer.

[0016] According to another possible embodiment of the method according to the invention, a load tap changer can be assigned to the transformer as a first switching means and two double reversing units as a second switching means. For the switching operation, a power unit assigned to the transformer is controlled by the control unit to actuate the load tap changer and at least one of the two double reversing units. Depending on the switching operation, the power unit actuates a first motor connected to the load tap changer via a drive shaft and a second motor connected to each of the two double reversing units via a drive shaft.

[0017] According to the inventive method, the parameters determined by the feedback systems are available for switching the at least one load tap changer and / or for switching the at least one double reversing switch for a position of the respective load tap changer and the respective double reversing switch. Furthermore, the parameter determined by the feedback systems for the load tap changer and double reversing switch required for switching can indicate whether the load tap changer and / or the double reversing switch are currently being actuated.

[0018] According to the method according to the invention, the parameters queried from the at least one on-load tap changer and the at least one double reversing switch are evaluated and combined in the control unit. Based on the result of the evaluation, the at least one on-load tap changer and / or the at least one double reversing switch can be controlled as required. According to another embodiment of the method according to the invention, three transformers are provided. Each of the three transformers is assigned a power unit. The power units are controlled by the central control unit, wherein the on-load tap changer of each of the three transformers is grouped into a first switching device group, the first double reversing switches of each of the three transformers into a second switching device group, and the second double reversing switches of each of the three transformers into a third switching device group.

[0019] In all embodiments of the inventive method described herein, a control unit monitors the existing load tap changers and double reversing devices. This monitoring determines the position of the load tap changer or the double reversing device. The parameter for the interlocking condition to be monitored is therefore the position of the load tap changer and / or the double reversing device, which is determined by the feedback system.

[0020] The feedback system can be a encoder, a multi-turn rotary encoder, a single-turn rotary encoder, a resolver, a switch, a microswitch, a sensor, a contact, etc. It is obvious to any expert that this list of possible feedback system configurations is not exhaustive.

[0021] The feedback system serves to determine the parameter necessary for verifying a locking condition. This parameter depends on the feedback system itself. Depending on the design, the parameter could be a value, a range of values, a simple signal, etc.

[0022] The feedback system, which is queried by a control unit, can be assigned to or configured as a temperature controller, circuit breaker, or similar device, depending on requirements. This allows any parameter queried by a feedback system to be used for an interlock condition. For example, a specific temperature parameter from a thermometer can be used to fulfill an interlock condition. Alternatively, a parameter from the status of a circuit breaker can be used. In this case, the feedback system is a sensor that outputs the parameter indicating whether the circuit breaker is open or closed, or is currently being opened or closed. Based on the interlock condition, the status of the circuit breaker is used to check whether the switching device to be actuated can / may be operated.The drive system according to the invention for at least one on-load tap changer and / or at least one double reversing unit of a transformer is characterized by a first motor connected to the at least one on-load tap changer via a drive shaft. A second motor is connected to each of the at least one double reversing unit via a drive shaft. A feedback system is assigned to each of the first motors and each of the second motors to determine at least one parameter of the at least one on-load tap changer and / or the at least one double reversing unit. A control unit, which is communicatively connected to a power unit, can actuate the on-load tap changer with the first motor and the double reversing unit with the second motor. Actuation of the on-load tap changer or the double reversing unit only occurs if the locking conditions determined by the at least one parameter are met.As an alternative to the parameter of the second feedback system on the second switching device, the parameter can also be determined by another feedback system, for example a protective contact or thermometer.

[0023] According to one possible design of the drive system, the transformer is assigned a single load tap changer and a single double reversing switch.

[0024] According to a possible further configuration of the drive system, three on-load tap changers are assigned to the transformer. Specific switching states or positions of the switching devices can be stored in the memory, which are, for example, assigned to a value for the position of the drive shaft.

[0025] According to a further embodiment of the drive system, a single load tap changer and two double tap changers are assigned to the transformer.

[0026] In a comprehensive configuration of the drive system, several transformers are assigned to it. Each transformer is assigned a power unit, and the power units are communicatively connected to a single central control unit. The on-load tap changers of the multiple transformers are grouped into a first switching device group. The first double reversing units of the multiple transformers are grouped into a second switching device group. The second double reversing units of the multiple transformers are grouped into a third switching device group. Each motor can be assigned its own power unit. A single power unit can also drive all motors.

[0027] The control unit and / or the power unit include a memory. This memory can store specific switching states or positions of the switching devices, which are, for example, assigned to a value for the position of the drive shaft.

[0028] The invention and its advantages will now be explained in more detail with reference to the accompanying drawings, using exemplary embodiments, without thereby limiting the invention to the embodiment shown. The proportions in the figures do not always correspond to the actual proportions, as some shapes are simplified and others are enlarged in relation to other elements for better illustration.

[0029] They show Figure 1 shows a drive system for at least one switching element in a transformer, according to one embodiment of the invention; Figure 2 shows a further embodiment of a drive system for at least one switching element in a transformer, according to another embodiment of the invention; Figure 3 shows yet another embodiment of a drive system for at least one switching element in a transformer; Figure 4 shows an embodiment of a drive system for several transformers; and Figure 5 shows a process sequence for carrying out a switching operation of at least one switching element in a transformer by means of a drive system according to the invention.

[0030] Identical reference numerals are used for identical or equivalently functioning elements of the invention. Furthermore, for the sake of clarity, only those reference numerals necessary for describing the respective figure are shown in the individual figures.

[0031] Figure 1Figure 1 shows a transformer 20 used for power transmission. This transformer has a first switching device 17, designed as a load tap changer, and a second switching device 18, designed as a double reversing switch. The load tap changer 17 is actuated by a first motor 12. The first motor 12 has a drive shaft 16 connected to the load tap changer 17. Furthermore, the first motor 12 is associated with a first feedback system 6, which determines the position or step position of the load tap changer 17. The double reversing switch 18 is actuated by a second motor 13. This second motor 13 is also connected to the double reversing switch 18 via a drive shaft 16. A separate feedback system 7 of the second motor 13 allows the position or step position of the double reversing switch 18 to be determined.A control unit 10 is connected to the first and second motors 12 and 13, and thus also to the feedback systems 6 and 7 of the on-load tap changer 17 and the double reverser 18. The control unit 10 receives signals to actuate the on-load tap changer 17 and the double reverser 18. Furthermore, the control unit 10 evaluates and combines different values ​​from the respective feedback systems 6 and 7. The control unit 10, the motors 12 and 13, and the feedback systems 6 and 7 form the drive system 3 for the on-load tap changer 17 and the double reverser 18 of the transformer 20.

[0032] The control device 2 according to the invention comprises the control unit 10, which receives switching signals during operation. If, for example, the voltage in the network drops, it must be adjusted, for example, by actuating the load tap changer 17 of the transformer 20. By using a double tap changer 18 with a corresponding connection of the windings (not shown) of the transformer 20, the control range or functional range of the transformer 20 is extended. After receiving the signal that the voltage needs to be changed, it is first determined whether the load tap changer 17 or the double tap changer 18, or both sequentially, need to be actuated. After it has been determined that the load tap changer 17 needs to be actuated, the interlocking conditions defined between the double tap changer 18 and the load tap changer 17 are checked.For example, a load tap changer 17 must not be actuated if the double reversing unit 18 is currently being actuated. This check is performed by the second feedback system 7 of the second motor 13 of the double reversing unit 18 reporting its current status or transmitting parameters to the control unit 10. The position of the double reversing unit 18 is determined and transmitted via the second feedback system 7. Furthermore, the second feedback system 7 reports whether the double reversing unit 18 is currently being actuated. If the determined parameters meet the interlocking conditions, the load tap changer 17 is actuated. If the interlocking conditions are not met, the load tap changer 17 is not actuated. Alternatively, the switching or actuation of the load tap changer 17 can be delayed until the interlocking conditions are met, i.e., until the double reversing unit 18 is in a specific position or no longer moving.

[0033] The control device 2 comprises the control unit 10 with a memory 5 and at least one power unit 11 with a memory 5. The memory 5 can, for example, store the assignment of switching positions of the load tap changer 17 and the double reversing switch 18. Likewise, the values ​​for the positions of the individual drive shafts 16 can be stored in the memory 5.

[0034] Figure 2Figure 3 shows the previously described drive system for three identical on-load tap changers 17, which are assigned to a single transformer 20. Here, too, each on-load tap changer 17 has its own first motor 12 and its own first feedback system 6. Upon receiving a switching signal, the system first determines which of the three on-load tap changers 17 is to be operated. It is also possible to select a sequence for operating the on-load tap changers 17. The interlocking conditions are also checked here. This is done using the transmitted parameters of the respective first feedback systems 6. The system also checks the position of the on-load tap changer(s) 17 that are not to be operated, and whether it is currently being operated. If the determined parameters meet the interlocking conditions, the selected on-load tap changer 17 can be operated.

[0035] Figure 3Figure 1 shows another embodiment of the described drive system 3. In this case, a load tap changer 17 and two double reversing switches 18 are provided as a second switching device 18. The load tap changer 17 and the two double reversing switches 18 are each actuated by their own first motor 12 and second motor 13, respectively. Each of the motors 12 and 13 is assigned a first feedback system 6 and a second feedback system 7, respectively. Here, too, different locking conditions can be checked in the control unit 10 by querying the parameters of the feedback systems 6 and 7. Thus, in this embodiment, actuation of the second double reversing switch 18 is only possible if the first double reversing switch 18 is in a safe position and the load tap changer 17 is in the center position (not shown). A safe position is defined as a specific first or second position of the double reversing switch 18.

[0036] Figure 4Figure 3 shows another embodiment of the described drive system. Three transformers 20 are shown here. The embodiment described here is a phase shifter with longitudinal and transverse control. Each of the transformers 20 has a load tap changer 17 (first switching element) and two double reversing elements 18 (second switching element). The configuration of the transformer 20 corresponds to the configuration of the embodiment from Figure 3. Figure 3 .Upon receiving a switching signal, the system first checks which of the on-load tap changers 17 and / or double reversing units 18 must be actuated. For this purpose, switching device groups 30, 40, and 50 can be formed. Thus, a first switching device group 30 consists of the on-load tap changers 17 in the respective transformers 20. A second switching device group 40 comprises the first double reversing units 18. A third switching device group 50 comprises the second double reversing units 18. Before actuation, it is then checked whether the specified switching device group 30, 40, or 50 meets the interlocking conditions. For example, the position of each of the first double reversing units 18 is checked, and whether any of them are moving. The interlocking conditions are checked using the parameters of the respective feedback systems 6 and 7.One of the interlocking conditions is that one of the switching device groups 40, 50 can only be operated if the load tap changers 17 of the first switching device group 30 are in a so-called neutral position (not shown). The power unit 11, which is assigned to each drive system 3 of each transformer 20, is connected via a bus 19 to a central and single control unit 10. The central control unit 10 coordinates and controls the operation of the respective load tap changers 17 or double reversing switches 18 for each of the three transformers 20. As shown in the... Figures 1 to 3 As shown, the power unit 11 accesses or operates the motors 12 or 13 assigned to the load tap changer 17 or double reversing switch 18.

[0037] Figure 5Figure 1 shows a process sequence according to the invention. Here, the control device 2 receives a switching signal for actuating a load tap changer 17 and / or a double reversing switch 18. This switching signal can be generated, for example, by manual input during maintenance work. Alternatively, the switching signal can be provided by a voltage control device when, for example, the voltage at the transformer 20 falls or rises. After receiving the switching signal, the control unit 10 queries at least one parameter. In the example from Figure 1The parameter being queried is the position of the double reversing switch 18, i.e., the second switching device 18, which determines the associated feedback system 6 of the first motor 12. The control unit 10 stores at least one interlock condition in a memory 5, which can be fulfilled or not fulfilled by this parameter. If the interlock condition is fulfilled during the check, the load tap changers 17 are switched by means of the first motor 12 assigned to them. If the interlock condition is not fulfilled during the check, the actuation of the load tap changer 17 can be aborted; thus, no switching occurs. Furthermore, an error message can be generated. However, the switching can also be carried out despite the interlock condition not being fulfilled in an emergency situation.Control unit 10 can then wait until the parameter meets the locking condition and then perform the switchover. Alternatively, the switchover can be aborted before it begins. Based on the example in . Figure 1Before actuating a load tap changer 17, the position of the double reversing unit 18 would first be checked, and / or it would be verified that the unit is currently being moved, i.e., actuated. Due to the interlocking conditions in this example, the load tap changer 17 must not be actuated if the double reversing unit 18 is currently being actuated or, for example, is in an unsuitable / unauthorized position. The parameters necessary for checking the interlocking conditions are output by the second feedback system 7 of the second motor 13 of the double reversing unit 18. The feedback system 6 or 7 is, for example, designed as a multiturn rotary encoder, which is connected directly or indirectly to the drive shaft 16 located between the second motor 13 and the double reversing unit 18. The multiturn rotary encoder then determines the parameters, such as the position of the double reversing unit 18, based on the position of the drive shaft 16.The first feedback systems 6 of the load tap changers 17 are designed analogously.

[0038] Depending on the design of the drive system 3, different parameters can be combined with different locking conditions. For example, as in the embodiment shown in Figure 3 Before actuating the load tap changer 17, the position of both double reversing switches 18 is checked. Alternatively, before actuating the second double reversing switch 18, the locking conditions, i.e., the parameters of the load tap changer 17 and the first double reversing switch 18, are checked. Here, too, the parameters are queried via the respective feedback systems 6 and 7, which are designed as multiturn rotary encoders.

[0039] The parameters to be queried can be defined arbitrarily and be of any type. The parameters can be determined from feedback systems 6 and 7 on the motors 12 and 13 of the respective load tap changers 17 and the respective double reversing tap changers 18, which can be simple safety switches of the transformer 20 or even customer-specific enabling buttons. Furthermore, the feedback systems 6 and 7 could be part of the control unit 10, which counts the switching operations or times a period and provides the single parameter to be queried for an interlock condition.

[0040] The feedback systems 6 and 7 are connected directly or indirectly to the drive shafts 16, which are arranged between the respective motors 12 and 13 and the load tap changer 17 and the double reversing unit 18, respectively. The parameters for the load tap changers 17 and the double reversing unit 18, such as step position, movement, etc., are determined from the positions of the drive shafts 16.

[0041] The interlocking conditions define which states must be met for a changeover to be prevented from being "locked," i.e., blocked. These conditions are linked to parameters that are formed or defined by the positions of the load tap changer 17 or the double reversing switch 18, the current status, and movement states.

[0042] The locking conditions can use one or more parameters from one or any number of feedback systems 6, 7.

[0043] The parameters include, for example, the movement states of the load tap changers 17 or the double reverser 18, the position of the load tap changers 17 or the double reverser 18, the position range of the load tap changers 17 or the double reverser 18, temperatures, customer-specific switching signals, safety devices and similar. Reference sign

[0044] 2 Control device 3 Drive system 5 Storage 6 First feedback system 7 Second feedback system 10 Control unit 11 Power section 12 First motor 13 Second motor 16 Drive shaft 17 Load step switch, first switching device 18 Double reverser, second switching device 19 Bus 20 Transformer 30 First switching device group 40 Second switching device group 50 Third switching device group

Claims

1. Method for bushing an advanced retard switch of at least one switching means (17, 18) of at least one equipment (20), wherein the equipment (20) is in each case a transformer, and wherein the switching means is in each case an on-load tap-changer (17) or a double-reversing tap-changer (18), characterized by the following steps: - in that a control unit (10) receives a switching signal; - in that the at least one switching means (17, 18) is selected for the advanced retard switch by means of the control unit (10) on the basis of the switching signal; - in that a respective interlocking condition for the selected at least one switching means (17, 18) is checked on the basis of at least one parameter; and - in that the advanced retard switch is bushed by means of the selected at least one switching means (17, 18) by means of a respective motor (12, 13) of the selected at least one switching means (17, 18) if the corresponding interlocking condition is fulfilled; wherein the at least one parameter comprises a position and / or a movement state of the selected at least one switching means (17, 18); and wherein a respective interlocking condition based on the at least one parameter defines whether a respective advanced retard switch is inhibited, such that the advanced retard switch can take place when the interlocking condition is fulfilled.

2. The method according to claim 1, wherein a plurality of parameters for the selected at least one switching means (17, 18) are evaluated in the control unit (10), and d ies plurality of parameters further comprises: one or more temperatures, customer-specific switching signals, a status of a circuit breaker or a safety device .

3. Method according to one of the preceding claims, wherein the at least one parameter is queried by the control unit (10) from a feedback system (6, 7) which is associated with a first motor (12) of a first switching means (17) and / or a second motor (13) of an at least second switching means (18).

4. The method according to claim 3, wherein the feedback system (6, 7) is associated with a drive shaft (16) for the first motor (12) and / or a drive shaft (16) for the second motor (12).

5. Method according to claim 4, wherein a power unit (11) assigned to at least one of the at least one piece of equipment (20) is actuated by the control unit (10) for actuating the selected at least one switching means (17, 18) and the power unit (11) actuates the respective selected switching means (17, 18) with the respective motor (12, 13) via the respective drive shaft (16) as a function of the determined interlocking condition .

6. Method according to one of the preceding claims, wherein three pieces of equipment (20) are provided and a power section (11) is assigned to each of the three pieces of equipment (20) and the power sections (11) are controlled by the control unit (10), wherein on-load tap-changers (17) of the three pieces of equipment (20) are combined to form a first switching means group (30), first double turners (18) of the three pieces of equipment (20) are combined to form a second switching means group (40) and second double turners (18) of the three pieces of equipment (20) are combined to form a third switching means group (50).

7. Method according to claim 1, wherein three on-load tap-changers (17) are assigned to the transformer (20) as switching means, wherein, for the bushing of the advanced retard switch, a power section (11) assigned to the transformer (20) is controlled by the control unit (10) to actuate one of the three on-load tap-changers (17) and the power section (11) actuates a motor (12) of the respective on-load tap-changer (17) via a drive shaft (16) as a function of the bushing of the advanced retard switch.

8. Method according to claim 1, wherein a load tap-changer (17) is assigned to the transformer (20) as a first switching means and a double tap-changer (18) is assigned to the transformer (20) as a second and third switching means, wherein, for the bushing of the advanced retard switch, a power section (11) assigned to the transformer (20) is actuated by the control unit (10) for actuating the load tap-changer (17) and at least one of the two double tap-changers (18), and the power section (11) actuates a first motor (12) connected to the on-load tap-changer (17) via a drive shaft (16) and a respective second motor (13) connected to one of the two double reversers (18) via a drive shaft (16) as a function of the bushing of the advanced retard switch.

9. Drive system (3) for at least one switching means (17, 18) of an equipment (20), wherein the equipment (20) is a transformer, and wherein the switching means is in each case an on-load tap-changer (17) or a double-reverser (18), characterized by: - a first motor (12), which is mechanically coupled via a drive shaft (16) to a first of the at least one switching means (17) of the equipment (20); - a control unit (10) which is communicatively connected to a power section (11) in order to actuate the first of the at least one switching means (17) with the first motor (12), provided that interlocking conditions based on at least one determined parameter and checked by the control unit (10) are fulfilled, wherein the at least one parameter comprises a position and / or a movement state of the at least one switching means (17, 18); and wherein a respective locking condition based on the at least one parameter defines whether a respective advanced retard switch is locked, such that the advanced retard switch can take place when the locking condition is fulfilled.

10. Drive system (3) according to claim 9, wherein the drive system is provided for two switching means (17, 18) of the equipment (20), the drive system (3) further comprising: - a second switching means (17, 18); - a second motor (13) which is mechanically coupled to the second switching means (18) via a drive shaft (16); wherein - the control unit (10) is communicatively connected to a power unit (11) to actuate the second switching means (18) with the second motor (13), provided that interlocking conditions based on the at least one determined parameter and checked by the control unit (10) are fulfilled.

11. Drive system (3) according to claim 10, wherein one feedback system (6, 7) each is assigned to the first motor (12) and the second motor (13) in order to determine at least one parameter of the first switching means (17) and at least one parameter of the second switching means (18).

12. The drive system (3) according to claim 11, wherein the feedback system (6, 7) is associated with the drive shaft (16) for the first motor (12) and the drive shaft (16) for the second motor (12), respectively.

13. Drive system (3) according to one of the preceding claims 9 - 12, wherein the drive system (3) is provided for three pieces of equipment (20), a power unit (11) is assigned to each piece of equipment (20) and the power units (11) are each connected to a single control unit (10) via a bus (19), wherein on-load tap-changers (17) of the equipment (20) are combined to form a first switching equipment group (30), first double tap-changers (18) of the equipment (20) are combined to form a second switching equipment group (40) and second double tap-changers (18) of the equipment (20) are combined to form a third switching equipment group (50).

14. Drive system (3) according to claim 9, wherein three on-load tap-changers (17) are assigned to the transformer (20).

15. Drive system (3) according to claim 9, wherein a single on-load tap-changer (17) and two double tap-changers (18) are associated with the transformer (20).

16. The drive system (3) according to any one of claims 9 to 15, wherein the control unit (10) and / or the power unit (11) comprise a memory (5).

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