Load transfer switch for a load tap changer and a method of manufacturing a load transfer switch

Abstract

The invention relates to a load changeover switch (2) for an on-load tap changer (1), comprising: - a housing (21); - a carrier (24) with elements (32) for carrying out a load changeover; wherein - the carrier (24) and the elements (32) are at least partially embedded in the housing (21).

Description

[0001] The invention relates to a load switch for a load tap changer and a method for manufacturing such a load switch.

[0002] Load tap changers are known from the prior art and typically comprise a load changer and a selector. The load changer incorporates vacuum switching tubes arranged in a vessel filled with insulating oil. The vacuum switching tubes are arranged in a frame around an actuating mechanism. The use of semiconductor switching elements as an alternative switching medium to vacuum switching tubes presents new challenges for the design and assembly of load tap changers.

[0003] Document FR 1396115 A discloses a load switch according to the preamble of claim 1.

[0004] The object of the invention is therefore to create a load changeover switch for a load tap changer that is resistant to insulating materials, has a high dielectric strength and is simple and compact in design.

[0005] This problem is solved by a load switch according to claim 1. The features of the dependent claims constitute advantageous further developments of the invention.

[0006] A further object of the invention is to create a method for manufacturing a load switch that is fast, simple and precise.

[0007] This problem is solved by a method according to claim 7.

[0008] According to a first aspect, the invention proposes a load changeover switch for a load tap changer, comprising: a housing; a carrier with elements for performing load switching; wherein the carrier with the elements is at least partially cast into the housing; and on which an optical communication interface and electrical contacts are arranged, which are at least partially cast or encapsulated.

[0009] By encasing or potting the carrier containing the elements used for load switching within the load transfer switch housing, these elements are protected from the insulating oil. Chemical reactions between the elements and the insulating oil are prevented. This significantly extends the service life of the elements and, consequently, the entire load transfer switch. Furthermore, the potting protects the elements against vibrations and other external mechanical stresses. Potting also increases the insulation distances between the individual elements. Flashovers are prevented, while simultaneously allowing for an increase in the operating voltage level.

[0010] For the purposes of the invention, "at least partially cast" or "encapsulated" means that the majority of the support and the elements are encased in a casting resin or silgel. However, due to the manufacturing process, individual edges or surfaces of the elements and the support may protrude, be exposed, or not be encased in the casting resin or silgel after casting. This applies, for example, to the contact surfaces between the support and a bridge in the housing to which the support is fixed.

[0011] The housing can be designed in any way, in particular in the shape of a bowl or cup. The housing can have a first region in which the support is arranged. Preferably, the first region is large enough that the support can be arranged at least partially or completely within it. The housing encloses the support at least partially or completely. The support is preferably designed as a circuit board, printed circuit board, or printed circuit.

[0012] The support and the elements for performing load switching are preferably at least partially encased or cast within the support using a casting resin or a silicone gel. The casting resin is preferably a polyurethane or epoxy resin. The silicone gel is preferably a silicone rubber that cures to a silicone gel.

[0013] The load switch may also include semiconductor switching elements and / or varistors and / or controllers and / or resistors and / or capacitors and / or MOSFETs and / or control units and / or transformers and / or rectifiers and / or current sensors, which are used as elements to perform load switching.

[0014] According to the invention, the carrier comprises an optical communication interface and electrical contacts, which are at least partially encapsulated or potted. The optical communication interface and the electrical contacts are preferably encapsulated at the interfaces to the controller and the selector only to the extent that contact with these parts is possible. Furthermore, the carrier can also have another communication interface that uses Bluetooth, WLAN, or radio, which is at least partially encapsulated or potted. This additional communication interface is preferably encapsulated at the interfaces to the controller and the selector only to the extent that contact with these parts or communication with these parts is possible. The load switch is preferably connected to a controller and a selector via the optical communication interface and the electrical contacts.The load switch can also be connected to the controller and selector via an additional communication interface, such as Bluetooth, Wi-Fi, or radio, and its electrical contacts. The load switch, selector, controller, and a motor drive together form a load tap changer. The load tap changer is located inside the transformer housing of a tap transformer.

[0015] According to a second aspect, the invention proposes a method for manufacturing a load switch, wherein: In a first step, the support with elements for carrying out load switching is placed or arranged in a first area of ​​the housing; in a second step, the support is at least partially encased in the first area and thus connected to the housing; in a third step, the housing with the encased support is dried.

[0016] The casting or encapsulation is preferably carried out using a casting resin or a silicone gel, wherein the carrier is at least partially encapsulated or encapsulated. The casting resin is preferably a polyurethane casting resin or an epoxy resin. The silicone gel is preferably a silicone rubber that becomes a silicone gel after curing.

[0017] The invention and its advantages are described in more detail below with reference to the accompanying drawings. These show: Fig. 1 a step-down transformer with a load switch; Fig. 2 a load switch according to the invention; Fig. 2 a sectional view of the load switch according to the invention; Fig. 3 a schematic sectional view of the load switch according to the invention.

[0018] Figure 1Figure 1 shows a load tap changer 1 with a load switch 2 and a selector 3, which are arranged in a tap changer 6. The load tap changer 1 also includes a motor drive 4 and a control unit 5. Unlike the other components, the control unit 5 is located outside the transformer housing 6.1. The tap changer 6 is filled with an insulating material 7, such as insulating oil, which surrounds those parts of the load tap changer 1 that are located inside the transformer 6. When the load tap changer 1 is actuated, the selector 3 preselects a winding tap of the tap changer 6 to be connected using its selector contacts. The load switch 2 performs the actual switching operation under load, switching from the current winding tap to the preselected winding tap. The control unit 5 controls the entire switching operation such that it acts on the motor drive 4 and thus on the selector 3.Furthermore, the control unit 5 acts on the load switch 2 and its elements 32, which are necessary for carrying out a load switching operation.

[0019] Figure 2a , Figure 2b and Figure 3The load switch 2 has a housing 21, which is designed in a vessel shape. On a first side 22 of the vessel-shaped housing 21, a first area 23 is formed in which a support 24 is arranged. The support 24 is preferably designed as a circuit board. The first area 23 has a base 25 and a circular wall 26 surrounding the base 25. The support 24 is preferably completely enclosed by the first area 23, or the support 24 is preferably located completely, but at least partially, within the first area. The support 24 is mechanically fixed in the housing 21 at defined points. Furthermore, the support 24 is encapsulated or cast in the first area 23 using a casting resin 30 or a silgel 31. The casting resin 30 can be an epoxy resin or a polyurethane casting resin. The polyurethane resin preferably consists of a triisocyanate-diisocyanate mixture and a triol-diol mixture.The casting resin 30 can also be designed as an epoxy resin, which is a synthetic resin with an epoxy group.

[0020] Various elements 32 of the load changeover switch 2 are arranged on or attached to the carrier 24. The load changeover switch 2 is a switching device used with a selector 3 to switch currents on and off in branches that have already been preselected by the selector 3. In other words, a load changeover switch 2 is the part of a load tap changer 1 that performs the actual switching from one winding tap to an adjacent winding tap under load. During this process, the selector 3 remains stationary such that its selector arms or selector contacts do not move.

[0021] Among other things, the elements 32 that perform or are necessary or required for the load switching are located on or attached to the carrier 24. These elements 32 are, for example, several semiconductor switching elements (IGBTs, TRIACs), varistors, resistors, capacitors, MOSFETs, control units, transformers, rectifiers, current sensors, and controllers.

[0022] Furthermore, at least one optical communication interface 40 and electrical contacts 41, designed as flat connectors, are located on or attached to the carrier 24. The optical communication interface 40 and the electrical contacts 41 are also at least partially encapsulated or potted. These can be directly adjacent to the housing 21 or extend through it. The load switch 2 is connected to the control unit 5 via the communication interface 40. The load switch 2 is electrically connected to the selector 3 and its selector contacts via the contacts 41. The carrier 24 also has recesses 42 through which air can escape during potting. This prevents air inclusions from forming between the carrier 24 and the housing 21 during potting.

[0023] The support 24, arranged in the vessel-shaped housing 21, rests at least partially on the base 25 of the first section 23. Furthermore, several webs 27 can be arranged on the base 25, by which the support 24 can be fixed at a distance from the base 25. The base 25 also has several protrusions 28 and depressions, which can likewise serve to support and fix the support 24. The support 24 can rest on the protrusions 28 and / or depressions. During casting, the support 24 and the elements 32 are preferably arranged below the outer wall edge 29, so that in the installed state they are preferably completely enclosed or embedded in the casting resin 30.

[0024] The support 24 and the elements 32 on or attached to the support 24 are preferably completely encapsulated or surrounded by the casting resin 30 or silgel 31. The housing 21, located in the insulating oil 7 of the transformer 6, and thus the support 24 and the elements 32, are protected from chemical reactions with the insulating oil 7 by the encapsulation. A further advantage of the encapsulation is that any contamination in the oil no longer shortens the insulating plugs, thus preventing their weakening. The optical communication interface 40 and the electrical contacts 41 are preferably encapsulated at the interfaces to the control unit 5 and the selector 3, respectively, only to the extent that contact with these parts is always possible.

[0025] The method for manufacturing or assembling the load transfer switch 2 is as follows. In a first step, the carrier 24 with the elements 32 for performing load switching is placed or arranged in a first area 23 of the housing 21. Here, the carrier 24 can be placed either on the base 25 of the housing 21, on at least one raised section 28, or on at least one web 27. By screwing or positively interlocking it with a web 27 or the housing 21, the carrier can be secured or fixed and aligned in the housing 21. In the next step, the carrier 24 together with the elements 32 is preferably completely encapsulated. This is done by pouring in a casting resin 30 or a silgel 31. After encapsulation, the load transfer switch 2 is dried in a curing oven under predefined parameters. A specified time, temperature, and humidity must be maintained during this process. During the drying of the casting resin 30 or silgel 31, the load transfer switch 2 is cured.The Silgels 31 then creates a connection between the carrier 24 and the housing 21, and the carrier 24 is protected from the insulating oil 7. Reference sign

[0026] 1 Load step switch 2 Load changer 3 Selector 4 Motor drive 5 Control 6 Step transformer 6.1 Transformer housing 7 Insulating oil 21 Housing 22 First side of 21 23 First area of ​​21 24 Support 25 Floor 26 Wall 27 Webs 28 Raises 29 Wall edge 30 Cast resin 31 Silgel 32 Elements 40 Communication interface 41 Electrical contacts 42 Recess

Claims

1. Diverter switch (2) for an on-load tap-changer (1), comprising: - a housing (21); - a carrier (24) with elements (32) for performing diverter switch operation; wherein - the carrier (24) and the elements (32) are at least partially encapsulated in the housing (21), characterized in that - an optical communication interface (40) and electrical contacts (41) are arranged on the carrier (24), which are at least partially encapsulated or potted.

2. Diverter switch (2) according to claim 1, wherein - the housing (21) is designed in a bowl- or cup-shaped configuration; - the housing (21) has a first region (23); - the carrier (24) is arranged at least partially in the first region (23).

3. Diverter switch (2) according to claims 1 to 2, wherein - the carrier (24) is configured as a circuit board.

4. Diverter switch (2) according to claims 1 to 3, wherein - the carrier (24) and the elements (32) are at least partially or completely encapsulated or potted in the housing (21) with a casting resin (30) or a silicone (31).

5. Diverter switch (2) according to claims 1 to 4, wherein - the elements (32) for performing a diverter switch operation comprise at least one semiconductor switching element and / or a voltage dependent resistor and / or a controller.

6. Diverter switch (2) according to claims 1 through 5, wherein - the diverter switch (2) is connected to a controller (5) via the optical communication interface (40) and to a selector (3) via the electrical contacts (41).

7. A method for manufacturing a diverter switch (2) according to any one of claims 1 to 6, wherein: - in a first step, the carrier (24) with elements (32) for performing a diverter switch operation is arranged in a first region (23) of the housing (21); - in a second step, the carrier (24) with the elements (32) is at least partially encapsulated in the first region (23) and thereby connected to the housing (21); - in a third step, the housing (21) with the encapsulated carrier (24) and the elements (32) is dried.

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