US3693070A - Tap changing apparatus for transformers - Google Patents

Tap changing apparatus for transformers Download PDF

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US3693070A
US3693070A US130711A US3693070DA US3693070A US 3693070 A US3693070 A US 3693070A US 130711 A US130711 A US 130711A US 3693070D A US3693070D A US 3693070DA US 3693070 A US3693070 A US 3693070A
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tapping
winding
fine
coarse
contact
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John Douglas Shorrock
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    • 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
    • H01F29/04—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings having provision for tap-changing without interrupting the load current
    • 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

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  • ABSTRACT Tap changing apparatus for a transformer includes an off-load tapping selector switch having its contacts connected to tappings on a coarse tapping winding, and a rotary diverter switch connected to the tapping selector switch and to tappings on a fine tapping winding. The arrangement enables any required part of the fine tapping winding to be connected in series with any required part of the coarse tapping winding.
  • Tap changing apparatus is provided for power transformers to enable the output voltage of the transformer to be maintained substantially constant under varying load conditions, or to enable the output voltage to be varied.
  • the tappings may be on either the primary or the secondary side of the transformer, and the tap changing apparatus is usually designed so that the tappings may be changed without disconnecting the load.
  • On-load tap changing apparatus consists basically of tapping selector switches arranged to operate only under no-load conditions and arranged to provide electrical connection to two adjacent tappings on the transformer winding, and an on-load diverter switch operable to select one or the other of the two positions of the selector switch. Changing the tapping on such an arrangement is thus a case of operating the diverter switch and the selector switches alternately, only moving the selector switch contacts which are not carrying current. In such a basic arrangement the number of output steps is equal to the number of tappings on the transformer winding.
  • tap changing apparatus of this type is that for each output step a separate lead has to be brought out from the transfonner winding. This may present a considerable problem when a large number of steps, possibly up to 30, is provided.
  • Tap changing apparatus is also known in which two selector switches are provided connected to tappings on coarse and fine tapping windings respectively, the selector switches still operating only off-load.
  • the onload diverter switch is still required, and hence three switches are necessary. This arrangement reduces the number of tapping leads but requires the use of an additional switch.
  • tap changing apparatus for use with a transformer having electrically-isolated coarse and fine tapping windings in which the number of turns between adjacent tappings on the coarse tapping winding is n times the number of turns between adjacent tappings on the fine tapping winding and in which the fine tapping winding comprises (n-l) sections, n being a positive integer greater than 2, the apparatus including an onload rotary diverter switch arranged to be connected to the tappings on the fine tapping winding and an offload tapping selector switch arranged to be connected to the tappings on the coarse tapping winding, the tappings on the fine tapping winding being so connected to the tapping selector switch and the rotary diverter switch that a selected part of the fine tapping winding is connectable in series with a selected part of the coarse tapping winding.
  • tapping is taken to include, where appropriate, an end of the winding in question.
  • FIG. 1 is a schematic diagram of a transformer connected to tap changing apparatus embodying the invention.
  • FIGS. 2 to 6 illustrate the operation of the tap changing apparatus of FIG. 1.
  • a transformer primary winding has a fine tapping winding 10 and a coarse tapping winding 11.
  • the coarse tapping winding has a number of equally spaced tapping points, and the number of turns of the winding between adjacent tappings is n times the number of turns between the adjacent tappings on the fine tapping winding 10.
  • the fine tapping winding comprises (n-l sections such that the voltage across the entire winding is equal to the voltage across one section of the coarse tapping winding.
  • the four tapping points on the fine tapping winding are denoted a, b, c and d, a and d being the two ends of the winding.
  • the coarse tapping winding 11 has one end connected to a terminal 12 and has five tapping points e, f, g, h and i, tapping e being the end of the winding opposite to that connected to the terminal 12.
  • the tap changing apparatus shown to the right of the chain-dotted line in FIG. 1, includes an off-load tapping selector switch 13 and an on-load rotary diverter switch 14.
  • the tapping selector switch has two rows of fixed contacts 15 and 16, corresponding contacts in each row being connected together as shown. These pairs of fixed contacts are each connected to a separate one of the tappings on the coarse tapping winding 11, and the fixed contacts are denoted by the reference 15 or 16 as appropriate, together with a letter denoting the tapping to which the contact is connected.
  • the tapping selector switch 13 also has two movable contacts 17 and 18. One of these, 17, makes electrical connection with one of the fixed contacts 15, whilst the other movable contact makes a connection with one of the fixed contacts 16.
  • the two movable contacts are provided with current collectors 19, and one of these, shown as 19d, is connected to the end d of the fine tapping winding 10.
  • the rotary diverter switch 14 has four fixed contacts 20 arranged symmetrically around a circular path, and a movable contact 21 pivoted at the center of the path.
  • One of the fixed contacts 20w is connected to the current collector 19w of movable contact 18 of the tapping selector switch, whilst the other three fixed contacts 20 are connected to the three remaining tappings a, b and c on the fine tapping winding, and are given appropriate references on the drawing.
  • the movable contact 21 is connected to a terminal 22.
  • the movable contact 21 in fact has three separate contact surfaces. One of these is the main contact 23 which is connected directly to the terminal 22.
  • the other two contact surfaces are auxiliary contacts 24 and 25 located one on each side of the main contact, and each is connected to the main contact through a separate diverter resistance 26 and 27 respectively.
  • the angular spacing between the three contact surfaces, and the size of each fixed contact 20 is such as to give the diverter switch 14 the usual make-before-break action required for on-load switching.
  • the transformer will have a secondary winding which has not been shown.
  • the supply is connected between terminals 12 and 22.
  • the connection is thus from terminal 12 through the coarse tapping winding 11 to tapping g, through fixed contact 15g and movable contact 17 of the tapping selector switch 13 onto the current collector 19d, through the entire fine tapping winding 10 from tapping d to tapping a, via fixed contact 20a of the rotary diverter switch 14 to the movable contact 21, and hence to terminal 22.
  • the trailing" auxiliary contact makes contact with the fixed contact segment 20a and the main contact 23 leaves the same fixed contact.
  • the tapping a on the fine tapping winding 10 is thus connected to the terminal 22 by way of the diverter resistance 27.
  • Further movement of the movable contact causes the leading auxiliary contact 24 to make contact with the fixed contact segment 20b, and hence that part of the fine tapping winding between tappings a and b is bridged by the two diverter resistances 26 and 27 in series, the junction between the two resistances being connected to terminal 22.
  • Continued movement of the movable contact brings the main contact 23 onto the contact segment 20b and the transition is complete.
  • a further reduction in the number of turns on the transformer primary is effected by moving the rotary diverter switch further in a clockwise direction, until the main contact 23 rests on auxiliary contact 20c.
  • the current path through the primary is as shown in FIG. 4.
  • the next step of the diverter switch causes the lower end of the fine tapping winding 10 to be disconnected from the current path by the engagement of contact 23 with auxiliary contact 20w, the moving contact 18 of the selector switch now being on fixed contact 16g and carrying current to the current collector 19d of the selector switch, as shown in FIG. 5.
  • the upper end d of the winding 10 is now connected to fixed contact 15g through collector 19d and contact 17 to prevent the winding from floating.
  • the movable selector contact 17 will have to be moved from fixed contact 15g to fixed contact 15h whilst the other movable selector contact 18 is carrying the current. Further clockwise rotation of the diverter switch then causes the full fine tapping winding 10 to be brought back into circuit in series with the selector contact 17 and current collector 19d.
  • the rotary diverter switch 14 is rotated in the opposite, anticlockwise, direction.
  • the first step therefore cuts out the fine tapping winding 10 and connects terminal 22 to tapping f on the coarse tapping winding, via the fixed contact 20w of the diverter switch and movable contact 18 and fixed contact 16f on the tapping selector switch.
  • the current path is then as shown in FIG. 6, the step described following that shown in FIG. 2.
  • the upper end of winding 10 is connected to a tapping on the coarse winding 1 l to prevent it from floating.
  • the tap-changing apparatus may be applied to the secondary of the transformer if required, both fine and coarse windings then being secondary windings.
  • the rotary diverter switch has been described as having four positions, but this number may be varied, so long as it is greater than two. Since the object of the invention is to reduce the number of tappings on the windings whilst providing the required number of tapping steps, the optimum number of positions on the rotary diverter switch depends upon the required number of steps. However, four appears to be a convenient number.
  • Tap changing apparatus for use with a transformer having electrically isolated coarse and fine tapping windings in which the number of turns between adjacent tappings on the coarse tapping winding is n times the number of turns between adjacent tappings on the fine tapping winding and in which the fine tapping winding comprises (n-l) sections, n being a positive integer greater than two, the apparatus including an onload rotary diverter switch having n fixed contacts (n-l of which are arranged to be connected to successive tappings on the coarse tapping winding and a movable contact capable of rotation in either direction and arranged to be connected to an output terminal, and an off-load tapping selector switch arranged to be connected to the tappings on the coarse tapping winding, the tappings on the fine tapping winding being so connected to the tapping selector switch and the rotary diverter switch that a selected part of the fine tapping winding is connectable in series with a selected part of the coarse tapping winding.
  • tape changing apparatus as claimed in claim 1 in which the movable contact of the rotary diverter switch comprises a main contact and a pair of auxiliary contacts located one on each side of the main contact and each connected thereto through a separate diverter resister.
  • tapping selector switch has a plurality of fixed contacts arranged in electrically-interconnected pairs with each pair arranged to be connected to a separate tapping on the coarse tapping winding, each l0

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Housings And Mounting Of Transformers (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

Tap changing apparatus for a transformer includes an off-load tapping selector switch having its contacts connected to tappings on a coarse tapping winding, and a rotary diverter switch connected to the tapping selector switch and to tappings on a fine tapping winding. The arrangement enables any required part of the fine tapping winding to be connected in series with any required part of the coarse tapping winding.

Description

United States Patent Shorr0ck 1 Sept. 19, 1972 TAP CHANGING APPARATUS FOR TRANSFORMERS [72] Inventor: John Douglas Shorrock, 49 Cavendish Road, Heaton Mersey, Stockport, England [22 Filed: April2, 1971 21 Appl.No.: 130,711
[30] Foreign Application Priority Data Feb. 27, 1970 Great Britain ..9,494/70 [52] US. Cl. ..323/43.5 R, 336/ 146 [51] Int. Cl. ..H02p 13/06, H02m 5/12 [58] field of Search ..336/146; 323/435 R [5 6] References Cited UNITED STATES PATENTS 3,122,698 2/1964 Ladd ..323/43.5 R
3,423,668 l/l969 Brennan ..323/43.5 R 3,174,097 3/1965 Bleibtreu ..323/43.5 R 3,461,379 8/1969 Okita ..323/43.5 R
Primary Examiner-Gerald Goldberg Attorney-Cameron, Kerkam & Sutton [57] ABSTRACT Tap changing apparatus for a transformer includes an off-load tapping selector switch having its contacts connected to tappings on a coarse tapping winding, and a rotary diverter switch connected to the tapping selector switch and to tappings on a fine tapping winding. The arrangement enables any required part of the fine tapping winding to be connected in series with any required part of the coarse tapping winding.
4 Claims, 6 Drawing Figures TAP CHANGING APPARATUS FOR TRANSFORMERS This invention relates to tap changing apparatus for transformers.
Tap changing apparatus is provided for power transformers to enable the output voltage of the transformer to be maintained substantially constant under varying load conditions, or to enable the output voltage to be varied. The tappings may be on either the primary or the secondary side of the transformer, and the tap changing apparatus is usually designed so that the tappings may be changed without disconnecting the load.
On-load tap changing apparatus consists basically of tapping selector switches arranged to operate only under no-load conditions and arranged to provide electrical connection to two adjacent tappings on the transformer winding, and an on-load diverter switch operable to select one or the other of the two positions of the selector switch. Changing the tapping on such an arrangement is thus a case of operating the diverter switch and the selector switches alternately, only moving the selector switch contacts which are not carrying current. In such a basic arrangement the number of output steps is equal to the number of tappings on the transformer winding. One of the problems arising from the use of tap changing apparatus of this type is that for each output step a separate lead has to be brought out from the transfonner winding. This may present a considerable problem when a large number of steps, possibly up to 30, is provided.
Tap changing apparatus is also known in which two selector switches are provided connected to tappings on coarse and fine tapping windings respectively, the selector switches still operating only off-load. The onload diverter switch is still required, and hence three switches are necessary. This arrangement reduces the number of tapping leads but requires the use of an additional switch.
It is an object of the invention to provide transformer tap changing apparatus capable of providing the required number of output steps whilst requiring a considerably reduced number of tappings on the transformer and using only two switches.
According to the present invention, there is provided tap changing apparatus for use with a transformer having electrically-isolated coarse and fine tapping windings in which the number of turns between adjacent tappings on the coarse tapping winding is n times the number of turns between adjacent tappings on the fine tapping winding and in which the fine tapping winding comprises (n-l) sections, n being a positive integer greater than 2, the apparatus including an onload rotary diverter switch arranged to be connected to the tappings on the fine tapping winding and an offload tapping selector switch arranged to be connected to the tappings on the coarse tapping winding, the tappings on the fine tapping winding being so connected to the tapping selector switch and the rotary diverter switch that a selected part of the fine tapping winding is connectable in series with a selected part of the coarse tapping winding.
In this specification the term tapping is taken to include, where appropriate, an end of the winding in question.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a transformer connected to tap changing apparatus embodying the invention; and
FIGS. 2 to 6 illustrate the operation of the tap changing apparatus of FIG. 1.
Referring now to FIG. 1, a transformer primary winding has a fine tapping winding 10 and a coarse tapping winding 11. The coarse tapping winding has a number of equally spaced tapping points, and the number of turns of the winding between adjacent tappings is n times the number of turns between the adjacent tappings on the fine tapping winding 10. The fine tapping winding comprises (n-l sections such that the voltage across the entire winding is equal to the voltage across one section of the coarse tapping winding. The four tapping points on the fine tapping winding are denoted a, b, c and d, a and d being the two ends of the winding. The coarse tapping winding 11 has one end connected to a terminal 12 and has five tapping points e, f, g, h and i, tapping e being the end of the winding opposite to that connected to the terminal 12.
The tap changing apparatus, shown to the right of the chain-dotted line in FIG. 1, includes an off-load tapping selector switch 13 and an on-load rotary diverter switch 14. The tapping selector switch has two rows of fixed contacts 15 and 16, corresponding contacts in each row being connected together as shown. These pairs of fixed contacts are each connected to a separate one of the tappings on the coarse tapping winding 11, and the fixed contacts are denoted by the reference 15 or 16 as appropriate, together with a letter denoting the tapping to which the contact is connected. The tapping selector switch 13 also has two movable contacts 17 and 18. One of these, 17, makes electrical connection with one of the fixed contacts 15, whilst the other movable contact makes a connection with one of the fixed contacts 16. The two movable contacts are provided with current collectors 19, and one of these, shown as 19d, is connected to the end d of the fine tapping winding 10.
The rotary diverter switch 14 has four fixed contacts 20 arranged symmetrically around a circular path, and a movable contact 21 pivoted at the center of the path. One of the fixed contacts 20w is connected to the current collector 19w of movable contact 18 of the tapping selector switch, whilst the other three fixed contacts 20 are connected to the three remaining tappings a, b and c on the fine tapping winding, and are given appropriate references on the drawing. The movable contact 21 is connected to a terminal 22. The movable contact 21 in fact has three separate contact surfaces. One of these is the main contact 23 which is connected directly to the terminal 22. The other two contact surfaces are auxiliary contacts 24 and 25 located one on each side of the main contact, and each is connected to the main contact through a separate diverter resistance 26 and 27 respectively. The angular spacing between the three contact surfaces, and the size of each fixed contact 20 is such as to give the diverter switch 14 the usual make-before-break action required for on-load switching.
It will be noted that only nine tapping connections have been brought out of the windings. As will be described later, this enables a very much larger number of tapping steps to be obtained.
As is well-known in the art, it is necessary to provide an operating mechanism and synchronizing means for ensuring the correct sequence of operations for the two movable selector contacts 17 and 18 and the movable diverter contact 21. However, such arrangements do not form part of the present invention.
The transformer will have a secondary winding which has not been shown.
The operation of he tap changing apparatus will now be described with reference to FIGS. 2 to 6.
If the two windings and 11 are considered as primary windings, then the supply is connected between terminals 12 and 22. The connection, as shown also in FIG. 2, is thus from terminal 12 through the coarse tapping winding 11 to tapping g, through fixed contact 15g and movable contact 17 of the tapping selector switch 13 onto the current collector 19d, through the entire fine tapping winding 10 from tapping d to tapping a, via fixed contact 20a of the rotary diverter switch 14 to the movable contact 21, and hence to terminal 22.
In order to increase the voltage from the secondary winding (not shown) or to compensate for a fall in voltage due to an increased load, it is necessary to reduce the number of effective turns on the primary of the transformer. This is done by rotating the movable contact of the diverter switch to fixed contact 20b, when the current path is as shown in FIG. 3.
As the movable contact 21 of the diverter switch is rotated in a clockwise direction the trailing" auxiliary contact makes contact with the fixed contact segment 20a and the main contact 23 leaves the same fixed contact. The tapping a on the fine tapping winding 10 is thus connected to the terminal 22 by way of the diverter resistance 27. Further movement of the movable contact causes the leading auxiliary contact 24 to make contact with the fixed contact segment 20b, and hence that part of the fine tapping winding between tappings a and b is bridged by the two diverter resistances 26 and 27 in series, the junction between the two resistances being connected to terminal 22. Continued movement of the movable contact brings the main contact 23 onto the contact segment 20b and the transition is complete.
A further reduction in the number of turns on the transformer primary is effected by moving the rotary diverter switch further in a clockwise direction, until the main contact 23 rests on auxiliary contact 20c. The current path through the primary is as shown in FIG. 4.
The next step of the diverter switch causes the lower end of the fine tapping winding 10 to be disconnected from the current path by the engagement of contact 23 with auxiliary contact 20w, the moving contact 18 of the selector switch now being on fixed contact 16g and carrying current to the current collector 19d of the selector switch, as shown in FIG. 5. The upper end d of the winding 10 is now connected to fixed contact 15g through collector 19d and contact 17 to prevent the winding from floating.
If the number of turns on the transformer primary is to be reduced still further, then the movable selector contact 17 will have to be moved from fixed contact 15g to fixed contact 15h whilst the other movable selector contact 18 is carrying the current. Further clockwise rotation of the diverter switch then causes the full fine tapping winding 10 to be brought back into circuit in series with the selector contact 17 and current collector 19d.
To increase the number of turns on the primary winding of the transformer, the rotary diverter switch 14 is rotated in the opposite, anticlockwise, direction. The first step therefore cuts out the fine tapping winding 10 and connects terminal 22 to tapping f on the coarse tapping winding, via the fixed contact 20w of the diverter switch and movable contact 18 and fixed contact 16f on the tapping selector switch. The current path is then as shown in FIG. 6, the step described following that shown in FIG. 2. As before, the upper end of winding 10 is connected to a tapping on the coarse winding 1 l to prevent it from floating.
Further anticlockwise rotation of the diverter switch reconnects the fine tapping winding via segment 20c of the diverter switch.
With the tap-changing arrangement described above, a total of 20 tapping steps are available, although only nine tapping connections have been brought out of the windings.
As already stated, means are known for synchronizing the movements of the three movable contacts 17, 18 and 21 so that the selector switch contacts move only when-they are not carrying current. As is usual, the diverter switch has a very rapid action so as to reduce the change-over time to a minimum.
The tap-changing apparatus may be applied to the secondary of the transformer if required, both fine and coarse windings then being secondary windings.
The rotary diverter switch has been described as having four positions, but this number may be varied, so long as it is greater than two. Since the object of the invention is to reduce the number of tappings on the windings whilst providing the required number of tapping steps, the optimum number of positions on the rotary diverter switch depends upon the required number of steps. However, four appears to be a convenient number.
What I claim is:
1. Tap changing apparatus for use with a transformer having electrically isolated coarse and fine tapping windings in which the number of turns between adjacent tappings on the coarse tapping winding is n times the number of turns between adjacent tappings on the fine tapping winding and in which the fine tapping winding comprises (n-l) sections, n being a positive integer greater than two, the apparatus including an onload rotary diverter switch having n fixed contacts (n-l of which are arranged to be connected to successive tappings on the coarse tapping winding and a movable contact capable of rotation in either direction and arranged to be connected to an output terminal, and an off-load tapping selector switch arranged to be connected to the tappings on the coarse tapping winding, the tappings on the fine tapping winding being so connected to the tapping selector switch and the rotary diverter switch that a selected part of the fine tapping winding is connectable in series with a selected part of the coarse tapping winding.
2. Tap changing apparatus as claimed in claim 1 in which the movable contact of the rotary diverter switch comprises a main contact and a pair of auxiliary contacts located one on each side of the main contact and each connected thereto through a separate diverter resister.
3. Tap changing apparatus as claimed in claim 1 in which the tapping selector switch has a plurality of fixed contacts arranged in electrically-interconnected pairs with each pair arranged to be connected to a separate tapping on the coarse tapping winding, each l0

Claims (4)

1. Tap changing apparatus for use with a transformer having electrically isolated coarse and fine tapping windings in which the number of turns between adjacent tappings on the coarse tapping winding is n times the number of turns between adjacent tappings on the fine tapping winding and in which the fine tapping winding comprises (n-1) sections, n being a positive integer greater than two, the apparatus including an on-load rotary diverter switch having n fixed contacts (n-1) of which are arranged to be connected to successive tappings on the coarse tapping winding and a movable contact capable of rotation in either direction and arranged to be connected to an output terminal, and an off-load tapping selector switch arranged to be connected to the tappings on the coarse tapping winding, the tappings on the fine tapping winding being so connected to the tapping selector switch and the rotary diverter switch that a selected part of the fine tapping winding is connectable in series with a selected part of the coarse tapping winding.
2. Tap changing apparatus as claimed in claim 1 in which the movable contact of the rotary diverter switch comprises a main contact and a pair of auxiliary contacts located one on each side of the main contact and each connected thereto through a separate diverter resistor.
3. Tap changing apparatus as claimed in claim 1 in which the tapping selector switch has a plurality of fixed contacts arranged in electrically-interconnected pairs with each pair arranged to be connected to a separate tapping on the coarse tapping winding, each contact of a pair being engageable by a different one of two movable contacts.
4. Tap changing apparatus as claimed in claim 3 in which one movable contact of the tapping selector switch is connected to the remaining fixed contact on the rotary diverter switch and the other movable contact of the tapping selector switch is arranged to be connected to one end of the fine tapping winding.
US130711A 1970-02-27 1971-04-02 Tap changing apparatus for transformers Expired - Lifetime US3693070A (en)

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GB949470 1970-02-27
FR7113453A FR2133516A1 (en) 1970-02-27 1971-04-16

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106463247A (en) * 2014-05-19 2017-02-22 赖茵豪森机械制造公司 Switching arrangement for a tap-changing transformer and method for operating a switching arrangement of this kind

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106463247A (en) * 2014-05-19 2017-02-22 赖茵豪森机械制造公司 Switching arrangement for a tap-changing transformer and method for operating a switching arrangement of this kind
CN106463247B (en) * 2014-05-19 2018-07-20 赖茵豪森机械制造公司 Method for the circuit system of adjustable transformer and for running this circuit system

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DE2108794A1 (en) 1971-09-09

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