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
  • H01H9/0027—Operating mechanisms
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F29/00—Variable transformers or inductances not covered by group H01F21/00
  • H01F29/02—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
  • H01F29/025—Constructional details of transformers or reactors with tapping on coil or windings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H19/00—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand
  • H01H19/02—Details
  • H01H19/03—Means for limiting the angle of rotation of the operating part
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H19/00—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand
  • H01H19/02—Details
  • H01H19/10—Movable parts; Contacts mounted thereon
  • H01H19/11—Movable parts; Contacts mounted thereon with indexing means
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H19/00—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand
  • H01H19/54—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand the operating part having at least five or an unspecified number of operative positions
  • H01H19/60—Angularly-movable actuating part carrying no contacts
  • H01H19/635—Contacts actuated by rectilinearly-movable member linked to operating part, e.g. by pin and slot
  • H01H19/6355—Contacts actuated by rectilinearly-movable member linked to operating part, e.g. by pin and slot using axial cam devices for transforming the angular movement into linear movement along the axis of rotation

Definitions

• the present invention relates generally to tap changers for transformers, and in particular to an arrangement for
• on-load tap changers In power transformers, on-load tap changers (OLTC) are used to change tapping connections of transformer windings while the transformer is energised. Since the transformer is in use, arcing will occur when the tapping connections are changed.
• Pre-selectors are used in on-load tap changers to enable connecting or disconnecting turns of the transformer winding. Pre-selectors may also be used to connect a whole part of a winding. Also in the contacts of the pre-selector, arcing will occur when the contacts are moved. If arcing is not
• tie-in-resistors are used to limit arcing in the contacts of the pre-selector. Instead of causing an arc, the energy stored when breaking the contacts of the pre-selector is released in the form of a controlled current through the tie-in-resistor. Although serving as a good working solution, there are some drawbacks with the tie-in-resistors.
• the pre-selector is securely locked when positioned in the appropriate position.
• the locking function of the pre-selector is achieved by two surfaces being in contact with each other by high friction.
• high friction between the surfaces is also caused when it is not wanted, i.e. when the pre ⁇ selector contacts are to be separated. If the contacts are not separated quickly, more arcing will occur during separation leading to unnecessary wear of the contacts and risk of damaging the transformer winding.
• This object is achieved by providing an arrangement for operating a pre-selector of a cylindrical tap changer that includes a cylinder provided with tap contacts and pre ⁇ selector contacts extending inside the cylinder, the
• the pre-selector arrangement comprises a contact carrier provided with at least one movable contact for mating the pre-selector contacts of the cylinder, and a drive mechanism for providing a rotational movement to the contact carrier, which contact carrier during use is rotated by means of the drive mechanism so that the movable contact selectively mate with the pre-selector contacts on the inside of the cylinder.
• the pre-selector arrangement is characterised in that the drive mechanism is operatively connected to the contact carrier via a staggering mechanism arranged to provide a rotation with varying angular velocity to the contact carrier.
• the geometric positioning of the contacts are provided so that the varying angular velocity is largest upon disconnection of the movable contact from the corresponding cylinder contact.
• the staggering mechanism includes a cam structure and a cam follower, which cam follower act on the cam structure during rotation.
• the cam follower act on the cam structure during rotation.
• the staggering mechanism comprises at least one end groove arranged to provide a first resting position for the mechanism coinciding with the movable contact being in a contact position with one of the cylinder contacts.
• the cam structure and cam follower provides the resting position, wherein the cam follower comprises a first and a second groove providing a first and second locking position for the cam follower, which locking positions provide the first and a second resting position of the mechanism.
• positions corresponds to an in-contact position of the movable contact and the corresponding contact of the cylinder.
• the cam structure comprises a first and a second cam and provides a groove between the first and second cam.
• This groove is an intermediate groove for controlling and limiting the rotational speed of the (cam follower and thereby the) movable contact during the movement between two
• the movable tap changing contacts of the tap changer are driven at essentially constant speed by the drive mechanism.
• the varying speed during operation of the preselector is essentially solely provided by the staggering mechanism, such as by the cam structure and cam follower construction .
• the tap changing contacts be movable by means of a
• the tap changer comprises vacuum interrupters for breaking currents in the tap changer during switching.
• Figure 1 illustrates the mechanism with the cam follower positioned in a first locking end position.
• Figure 2 illustrates the mechanism with the cam follower moved to a first cam position.
• Figure 3 illustrates the mechanism in an intermediate
• Figure 4 illustrates the cam follower moved to a second cam.
• Figure 5 illustrates the system where the cam follower is positioned in a second locking and end position.
• Figure 6 illustrates a perspective view of parts of a pre ⁇ selector .
• Figure 7 illustrates a transformer with a tap changer.
• Figure 8 illustrates the main parts of a tap changer and means for switching the tap changer.
• Figure 7 illustrates an overview of a transformer 11 having a first 12 and a second 13 set of terminals for transforming electricity between a first voltage level and a second voltage level.
• the transformer 11 is provided with a tap changer 10, having three sets of tap changing contacts, one for each phase, symbolically illustrated, below a pre-selector having three output contacts 26, 27, 28.
• Figure 7 illustrates a known type of transformer tap changer which can benefit from being equipped with a pre-selector arrangement of the invention.
• Figure 8 illustrates main parts of a tap changer, including a pre-selector arrangement in accordance with the invention.
• the tap changer 10 includes a motor 22 for driving the tap
• the tap changer operatively connected via linking means 23 to a drive mechanism 21 of the tap changer.
• the tap changer also serves as a drive mechanism 21 of the tap changer.
• the transformer housing the cylinder is provided with annular tap changing contacts, and a switching shaft is arranged inside the cylinder.
• the switching shaft 25 carries movable contact parts, i.e. moves with the shaft, which contacts is arranged to selectively mate with the corresponding contact parts of the cylinder.
• the drive mechanism 21 is arranged to provide a driving torque to rotate the switching shaft 25 whereby the contacts of the tap changing part of the tap changer is manoeuvred.
• the drive mechanism is also operatively connected to the pre-selector and is arranged to drive a contact carrier 9 of the pre-selector that carries the movable pre-selector contacts 8.
• the movable pre-selector contacts 8 are arranged to selectively mate with the fixed pre-selector contacts 26, 27, 28 of the cylinder, when rotated by the drive mechanism 21.
• the drive mechanism 21 may include a Malteser wheel gear for providing rotation to both the switching shaft 25 of the tap changer and the contact carrier 9 of the pre-selector.
• Tap changers having Malteser wheel gears have been provided in several versions by ABB AB (for example the UC tap changer with a BUE or BUL drive mechanism, or of type UZE/UZF with drive BUF 3) , and this gear mechanism will not be described in further detail herein.
• the pre-selector also includes a mechanism 1 for varying the speed of the movable contact.
• This mechanism 1 is provided to transform a uniform rotating motion input from the drive mechanism 21 into a staggered rotating motion applied to the contact carrier 9.
• the staggering mechanism 1 provides a staggering rotation, wherein the speed varies and the
• staggering mechanism 1 is operatively connected the contact carrier 9 so that the greatest speed coincides with the disconnection moment for the movable contact 8, i.e. the moment where the movable contact 8 leaves the fixed cylinder contact 26, 27 or 28.
• the staggering mechanism makes a faster separation of the contacts possible.
• the staggering mechanism of the preferred embodiment comprises a cam structure 5 and a cam follower 2 that is arranged to cooperate with the cam structure to provide an alternately halting and accelerating motion.
• the cam follower 2 is secured to a shaft 3, which is coupled to the drive mechanism 21, and is arranged to impart a rotating motion to the cam follower 2 from the drive mechanism 21.
• the cam follower 2 is spring loaded by means of a spring 4 into contact with the surfaces of the cam structure.
• the cam structure 5 comprises a first 16 and a second 18 groove, providing a first and a second end position for the cam follower in the cam structure.
• first 5a and a second 5b cam are arranged and between these cams 5a, 5b are a third groove 17 arranged, provided as an intermediate position for the cam follower 2.
• the staggered motion is created by moving the cam follower 2 between the grooves 16, 17, 18 passing the cams 5a, 5b.
• Figure 6 illustrates a perspective view of parts of the pre ⁇ selector arrangement with movable contact 8 and staggering mechanism.
• the tap changer cylinder is provided with external pre-selector tap contacts 7 extending into the cylinder and providing the interior cylinder contacts 26-28 of the pre ⁇ selector that are arranged to selectively mate the movable contact 8 carried by the contact carrier 9.
• FIG. 1-5 illustrates passages for the cam follower 2 running over the cam structure 5 during a switching operation of the pre-selector .
• the cam follower 2 is situated in the first groove 16 providing the first end position for the staggering mechanism. This end position corresponds to a contact position for the movable contact of the pre-selector, thus, in the end position the movable contact 8 mate with a first one of the fixed cylinder
• Figure 5 shows the opposite end position wherein the movable contact 8 of the pre-selector switch mates a second one of the fixed contacts of the cylinder 2.
• This acceleration phase increase the speed up to a top speed, which suitably is made to coincide substantially with the switching phase where the movable contact 8 loses contact and
• the top speed is reached slightly after the point in time where the contacts separate so that the risks for arcs are minimal.
• FIG. 3 illustrates the cam follower 2 entering the
• Figure 4 illustrates the cam follower 2 reaching the top of the second cam 5b, where the rotational speed has decreased to minimum again.
• the cam follower 2 will run down the second cam 5b, wherein the compressed spring 4 contributes once again to the rotational speed and the cam follower 2 enters into the second end groove 18.
• the entering into the second end groove is made to coincide with the entering of the movable contact 8 into contact with a second contact of the fixed contacts on the cylinder.
• the end position is

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=43567576

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (2)

Citations (4)

Family Cites Families (2)

• 2010
  • 2010-07-06 WO PCT/EP2010/059678 patent/WO2012003864A1/en active Application Filing
  • 2010-07-06 KR KR1020137003045A patent/KR101465910B1/ko active IP Right Grant
  • 2010-07-06 EP EP20100731730 patent/EP2591484B1/en active Active
• 2011
  • 2011-07-05 CN CN201110193915.5A patent/CN102315029B/zh active Active
  • 2011-07-05 CN CN2011202396842U patent/CN202275735U/zh not_active Expired - Lifetime

Patent Citations (4)

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