Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/0005—Tap change devices
  • H01H9/0016—Contact arrangements for tap changers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H3/00—Mechanisms for operating contacts
  • H01H3/32—Driving mechanisms, i.e. for transmitting driving force to the contacts
  • H01H3/42—Driving mechanisms, i.e. for transmitting driving force to the contacts using cam or eccentric
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/0005—Tap change devices
  • H01H9/0027—Operating mechanisms

Definitions

• the present disclosure is related to a contact system for an tap changer and a corresponding tap changer.
• Tap changers realize a mechanism in transformers which allows for variable turn ratios to be selected in distinct steps, for example.
• a contact system for a tap changer comprises a first and a second fixed or stationary contact unit each with at least one fixed electrical contact element.
• the contact system further comprises a movable contact unit with at least one movable electrical contact element that is configured to make electric connection to the respective contact element of the associated fixed contact unit.
• the moveable contact unit comprises a two-level driving contact with contact portions which are arranged offset to each other with respect to a rotation axis of the moveable contact element.
• the contact system further comprises a driving unit that is configured to rotationally drive the movable contact element bidirectionally around the rotation axis of the moveable contact element towards the respective fixed contact element of the associated fixed contact unit.
• the driving unit also comprises a two-level driving contact with protrusions which are arranged offset to each other with respect to a rotation axis of the driving unit.
• the movable contact unit and the driving unit are configured in coordination with each other so that a respective protrusion is temporarily in contact with the associated contact portion to drive the movable contact element so that a first state and a second state can be set or adjusted.
• the first state the movable contact element is in electrical contact with the contact element of the first fixed contact unit.
• the moveable contact element is in electrical contact with the contact element of the second fixed contact unit.
• an electric connection mechanism for a tap changer is feasible that allows for a stable and reliable functioning and that contributes to low wear and low friction of interacting components and less precision requirements.
• the contact system enables fast motion for a tap changer acting independently of the positioning of a driving shaft of the driving unit.
• Such a motion resistor contact system is applicable for a vacuum-type on-load tap changer (OLTC), and can be controlled by a two-level cam and independent of an end positions of a driving shaft of the driving unit.
• the moveable contact element is formed with ramifications comprising a first and a second arm realizing the contact portions of the two-level driving contact of the moveable contact unit.
• the driving unit comprises a cam or control disc element with a first and a second protrusion realizing the two-level driving contact of the driving unit.
• the arms and the protrusions are configured in coordination with each other so that the first protrusion is temporarily in contact with the first arm and the second protrusion is temporarily in contact with the second arm to respectively drive the movable contact element and to set the first state or the second state of the contact system.
• the control disc element and the first and second protrusions are formed integrally in one piece.
• the moveable contact element and the first and second arms are formed integrally in one piece.
• the respective protrusion of the driving unit comprises a circumferentially tapering shape along a circular path around the rotation axis of the driving unit so that the respective protrusions each have a wider section and a narrower section.
• the respective wider sections are preferably facing each other circumferentially in relation to a top view of the control disc element, for example.
• the respective wider section is configured to contact the associated contact portion for driving the movable element so that the first state and the second state of the contact system are settable independent of a rotational end position of the driving unit.
• the respective contact elements of the fixed contact units each comprise a chamfered or wedge-shaped contact section.
• the movable contact element comprises a rod-shaped electrical contact portion with rounded contact tips at opposite ends of the rod-shaped contact portion.
• the moveable contact element and the electrical contact portion are formed integrally in one piece.
• the electrical contact portion comprises buffer protrusions at opposite sides which are configured in coordination with buffer elements of the fixed contact units to set a rotational end position of the movable contact element.
• the fixed contact units each comprise two or more contact elements formed spaced apart from each other with a given distance in between that is formed in coordination with a thickness of a contact portion of the moveable contact element.
• the moveable contact unit and the fixed contact units can be configured in reverse so that the moveable contact unit comprises two or more contact elements formed spaced apart from each other with a given distance in between that is formed in coordination with a thickness of a contact portion of the respective fixed contact unit.
• the fixed contact units each comprise two pivotable contact elements with respective contact sections which are configured to make electrical contact to the movable contact element in the first or the second state.
• the fixed contact units each further comprise a spring element that is arranged between and coupled to the respective contact arms so that the contact arms are pretensioned and the associated contact sections are pressed towards each other.
• the moveable contact unit and the fixed contact units can be configured in reverse so that the movable contact unit comprises two pivotable contact elements with respective contact sections which are configured to make electrical contact to a contact portion of the respective fixed contact unit in the first or the second state.
• the contact portions of the movable element each comprise a rotatable roller element that is configured to get in contact with the associated protrusion of the driving unit when the movable contact element is to be rotated.
• the protrusions of the driving unknit each comprise a curved contact surface facing and configured to get in contact with the associated contact portion of the movable contact unit when the movable contact element is to be rotated.
• the protrusions of the driving unit are formed at a given radial distance from the rotation axis of the driving unit.
• the contact portions of the movable contact element are arranged in coordination with the radial distance of the associated protrusion so that, when the interacting contact portion and protrusion are free of contact and the driving unit rotates, the protrusion is moved towards the contact portion, contacts the contact portion and drives the moveable element towards one of the fixed contact units.
• a tap changer e.g. an on-load tap changer, for setting a gear ratio
• a tap changer for setting a gear ratio
• the driving unit of the contact system is coupled to the shaft.
• some designs for contact concepts or switching schemes with diverter switches with vacuum interrupters include an acting main and resistor contact system.
• the main contact system is usually actuated in a middle of a stroke of a symmetrically rotating main shaft.
• the resistor contact system can be actuated at both ends of a set angle of rotation of the shaft.
• Such a set up requires a plurality of additional drive parts and it is difficult to perform or assemble.
• such a set up includes the adverse effect that a driving surface of the driving element mounted on the main shaft after pushing a driven contact continues its movement together with it until a final position of the shaft is reached.
• the contact portions and the protrusions can also be referred to as upper and lower contact portion or protrusion, respectively.
• the contact system is feasible with a clear, compact and simple design of a rotatable fast-motion resistor contact system which acts near an end of the stroke of a main driving shaft, performing a switching operation. Due to the specific design, a single rotating contact can be driven by control surfaces located on the respective two-level driving contact of a specially profiled cam or control disc element and the one of the moveable contact unit, one for each of the two directions of rotation.
• the control disc element is mounted on the main driving shaft, which after performing the switching operation continues its movement as long as necessary until its final position is reached.
• the cam profile provides locking of the contact in the desired position when final position of the shaft is reached.
• the described configurations of the contact system and the corresponding tap changer each enable a simple fast motion contact system with acting independently of the positioning of the driving shaft.
• the contact system and the tap changer enable or provide at least some of the following features and/or advantageous:
• the figures 1-6 each illustrate a perspective view of components for a tap changer, e.g. an on-load tap changer, for a transformer which can allow for variable turn ratios to be selected in distinct steps without a supply interruption during a tap change.
• the on-load tap changer comprises a contact system 1 that enables a stable and reliable electrical connecting mechanism and contributes to low wear and low friction of interacting components.
• the contact system 1 comprises a first and a second fixed contact unit 20 and a movable contact unit with a movable electrical contact element 10.
• the fixed contact units 20 each comprise two plate-shaped fixed electrical contact elements 24.
• the associated contact elements 24 are formed spaced apart from each other with a given distance in between that is formed in coordination with a thickness of a contact portion 14 of the moveable contact element 10.
• the movable contact element 10 is configured to make electrical connection to the respective contact elements 24 of the associated fixed contact unit 20.
• the moveable contact element 10 comprises a two-level driving contact with contact portions 11 and 12 which are arranged offset to each other with respect to or along a rotation axis R2 of the moveable contact element 10.
• the contact system 1 further comprises a driving unit 3 that is configured to rotationally drive the movable contact element 10 bidirectionally around the rotation axis R2 towards the respective fixed contact elements 24 of the associated fixed contact unit 20.
• the driving unit 3 comprises a two-level driving contact with protrusions 6, 7 which are arranged offset to each other with respect to or along a rotation axis R1 of the driving unit 3.
• the movable contact unit and the driving unit 3 are configured in coordination with each other so that a respective protrusion 6, 7 is temporarily in contact with the associated contact portion 11, 12 to drive the movable contact element 10 so that a first state and a second state can be set.
• the movable contact element 10 is in electrical contact with the contact elements 24 of the first fixed contact unit 20 (e.g.
• the moveable contact element 10 In the second state, the moveable contact element 10 is in electrical contact with the contact elements 24 of the second fixed contact unit 20 (e.g. see Fig. 5 ).
• the Figs. 4 and 6 show a transition between the first and the second state, wherein the movable contact element 10 is not in contact with the contact elements 24 of the first and the second fixed contact unit 20.
• the contact system 1 can be implemented in one of the phases of a diverter switch for an on-load tap changer.
• the contact system 1 is mounted on an insulating plate 2 and comprises the two fixed contact units 20 each including two opposite fixed insulating blocks 21 of insulating material which are associated to the respective pair of clip contact elements 24.
• the contact elements 24 are rotatable or pivotable around a corresponding rotation axis R3 (see Fig. 1 ).
• a contact pressure is set by an associated spring 26.
• the axle 16 is arranged inside an axle recess 17 of the movable contact element 10 (see Figs. 7 and 8 ).
• the moveable contact element 10 is formed with ramifications comprising a first arm 11 and a second arm 12 realizing the contact portions of the two-level driving contact of the moveable contact unit.
• the driving unit 3 comprises a control disc 5 with the first protrusion 6 and the second protrusion 7 realizing the two-level driving contact of the driving unit 3.
• the arms 11, 12 and the protrusions 6, 7 are configured in coordination with each other so that the first protrusion 6 is temporarily in contact with the first arm 11 and the second protrusion 7 is temporarily in contact with the second arm 12 to respectively drive the movable contact element 10 and to set the first state or the second state of the contact system 1.
• the first arm 11 can also be referred to as the upper arm and the second arm 12 can also be referred to as the lower arm.
• the first protrusion 6 can also be referred to as the upper protrusion and the second protrusion 7 can also be referred to as the lower protrusion.
• the movable contact element 10 comprises a rod-shaped electrical contact portion 14 with rounded contact tips 15 at opposite ends of the contact portion 14 (see Figs. 4 and 6-8 ).
• the respective contact elements 24 of the fixed contact units 20 each comprise a chamfered or wedge-shaped contact section 25 interacting with the rounded contact tips 15 of the movable contact element 10 proving a precise and reliable contact making.
• the movable contact element 10 is arranged between the fixed contact units 20 and the driving unit 3. In a rear part of the contact element 10 there are two levels of rollers 13, the axes of which do not coincide, but are shifted at an appropriate predetermined angle.
• the drive of the movable contact 10 is carried out by the control disc 5, which has the two convex cam profiles or teeth forming the protrusions 6 and 7 located at two levels, which correspond to the levels on which the rollers 13 are located on the contact element 10.
• the contact makes the electrical connection between the corresponding contact elements 24.
• the current transmitting contact element 10 is locked between an outer surface of the corresponding protrusion 6, 7 and a buffer 22 of the respective fixed contact unit 20 (see Fig. 2 ).
• the buffer 22 then contacts a respective buffer protrusion 18 of the movable contact element 10 (see Fig. 8 ).
• the control disc 5 When performing a switching operation, initially the control disc 5 passes a set idle travel, after which the corresponding protrusion 6, 7 hits the respective roller 13, which starts the movement of the movable contact element 10 (see Fig. 4 ). Arrows shown in Fig. 3 indicate a movement direction of the corresponding movable elements. In this movement, the other roller 13 moves freely, and preferably does not touch anything, and does not participate in the steering. Thus, there can be a gap between the roller 13 and the associated protrusion 6, 7 after the desired rotation of the moveable contact element 10. Upon completion of the switching operation, the contact element 10 engages between the two contact elements 24 making an electrical connection between them.
• the roller 13 has turned to such an angle that it can no longer be pushed by the associated protrusion 6, 7 but can roll against an outer cylindrical surface, whereupon the movement of the contact 10 stops to the buffer 22 (e.g. see Fig. 5 ).
• the movement of a diverter switch control shaft 4, on which the control disc 5 is mounted can continue without restrictions, until reaching the angle set for it.
• the shaft 4 with the control disc 5 is rotated in the opposite direction, using the other protrusion 7 and the roller 13, located at the upper level to drive the contact element 10, as shown in Figure 6 , until reaching the other end position shown in the Figs. 1 and 2 .

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Citations (4)

• 2024
  • 2024-06-14 EP EP24182240.2A patent/EP4664501A1/de active Pending
• 2025
  • 2025-05-22 WO PCT/EP2025/064056 patent/WO2025256881A1/en active Pending

Patent Citations (4)

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