GB2542107A - Winding former - Google Patents

Abstract

A winding former 20 is disclosed for forming a coil 22 for use as a distributed winding in a rotating electrical machine. The winding former is arranged to be inserted into slots 44 in the electrical machine together with the coil. This may facilitate insertion of the coil and help to achieve a higher slot fill. Once inserted, the former itself ay act as an insulating barrier between the coil and the slots. The winding former and coil are arranged for axial insertion into slots in the stator 40 of the machine., the coil being wound on the former in planar form and the end 26 then being bent up supported by the lugs 36,38 so that the assembly can be inserted in the core slots When fully inserted the end turns 26 an be shaped as required and may be realigned in an axial direction out of the slots. Single, double or partially lapped windings may be formed, coils being inserted one at a time.

Description

WINDING FORMER

The present invention relates to techniques for installing distributed windings in rotating electrical machines, as well as to a former for use in the installation of such windings.

Rotating electrical machines, such as motors and generators, generally comprise a rotor and a stator separated by a small air gap. A magnetic flux developed by the rotor crosses the air gap and combines with stator windings. In the case of a generator, when the rotor is rotated by a prime mover, the rotating magnetic field causes an electrical current to flow in the stator windings, thereby generating the electrical output. In the case of a motor, an electrical current is supplied to the stator windings and the thus generated magnetic field causes the rotor to rotate.

Conventional stator core assemblies consist of a pre-built stator core made from steel laminations with slots stamped into the inner circumference. During manufacture, the stator windings may be wound into the slots in situ, or else preformed coils of windings may be inserted into the slots. The slots are typically lined using an insulation paper which prevents the coils from making direct contact with the steel core.

The windings used in electrical machines can generally be classified as either concentrated or distributed. In the case of concentrated windings, all the winding turns are wound together to form one multi-turn coil for each pole. In the case of distributed windings, the winding turns are distributed in two or more slots spaced around the machine. Distributed windings may provide various advantages over concentrated windings, such as relatively good spatial sinusoidal magneto-motive force with lower harmonics, lower operational vibration, and better thermal efficiency. For these reasons, many rotating electrical machines such as induction motors and synchronous machines use distributed windings in order to help achieve performance requirements.

Coils for distributed windings are commonly formed by tumble winding multiple turns of enamel coated copper wire onto a winding former using a winding machine. These coils are then removed from the winding former and placed loosely onto “draw-in” tooling that pulls the coils through the stator core whilst pushing them down through the slot openings.

The known techniques for winding and inserting distributed windings may suffer from various disadvantages. These include high frictional forces being placed onto the coils by the insertion tooling which can damage the enamel coating, loose coils becoming damaged during transfer between the winding tooling and the insertion tooling, wires from separate coil turns being inadvertently mixed together, low slot fill, and high labour requirements. Furthermore, once removed from the winding former, all tension and placement of the wires is lost, making the process of producing high density coils difficult. Due to the lack of control over the flexible, loose coils, full automation may be difficult or impossible.

According to a first aspect of the present invention there is provided a winding former for forming a coil for use as a distributed winding in a rotating electrical machine, wherein the winding former is arranged to be inserted into slots in the electrical machine together with the coil.

The present invention may provide the advantage that, by providing a winding former which is arranged to be inserted into slots in the electrical machine together with the coil, the coil can be more easily inserted into the slots whilst retaining its shape. This may facilitate insertion of the coil, thereby reducing labour requirements when installing distributed windings. The present invention may also help to achieve a higher slot fill, by at least partially retaining tension and/or placement in the coil. Furthermore, once inserted the former itself may act as an insulating barrier between the coil and the slots. This may help to prevent short circuits between the coil and the slots during the machine’s operation.

In a preferred embodiment, the winding former is used to form a coil for a distributed stator windings. Thus the slots may be slots in the stator of the electrical machine. However the present invention may also be used to install windings in the rotor of a rotating electrical machine.

The former is preferably arranged to be inserted into two slots which are not adjacent to each other. This may allow the formation of distributed windings in the electrical machine.

The stator of a rotating electrical machine typically comprises a number of teeth which define the stator slots. The teeth may have teeth tips extending in a generally circumferential direction, in order to partially close the slots. This may help with the electromagnetic properties of the stator. However the partially closed slots may make insertion of the coils more difficult.

In a preferred embodiment of the invention, the winding former is arranged for axial insertion of the former and the coil into the slots. By arranging the winding former for axial insertion into the slots, it may be possible to insert the coil with minimum disruption to the placement of wires in the coil. This may help to achieve a higher slot fill, thereby improving the performance of the machine. A coil for a distributed winding typically comprises two side windings for insertion into the slots, and two end windings which, following insertion, extend outside of the slots. The two side windings typically run in a substantially axial direction through the machine, while the two end windings typically loop between two slots.

Preferably the former is arranged to support at least two side windings and one end winding of the coil. For example, the former may be substantially U-shaped, and may be arranged to extend around the two side windings and one end winding. This may facilitate winding of the coil on the former, and allow the former to help retain the shape of the coil.

The former is preferably arranged such that one end winding of the coil is unsupported by the former. In this case the former may be arranged such that the unsupported end winding can be re-shaped. For example, the winding former may be arranged such that the unsupported end winding can be reshaped so as to sit clear of the slots during axial insertion of the former and the coil into the slots. This may be achieved by bending the unsupported end winding out of the plane of the rest of the coil. For example, the unsupported end winding may be bent so as to exit the slots in a radial direction during insertion. This may facilitate axial insertion of the former and the coil into the slots. Preferably the reshaping also ensures that the wires which pass through the slots are suitably placed to minimize frictional forces placed on them during insertion.

Alternatively the end winding may be shaped during winding to sit clear of the slots. In either case, the former may be arranged such that the end winding can be reshaped following insertion so as to exit the slots in an axial direction. This may help to minimize the machine’s dimensions and to ensure optimal shape of the windings for cooling.

The former may comprise a lug for protecting the unsupported end winding as it is inserted into the slots. The lug may be arranged to extend in a substantially radial direction through and/or out of a slot. For example, where the slots are formed by teeth having teeth tips, the lug may help to protect the unsupported end winding from the teeth tips. In this case the lug is preferably shaped so as to correspond to the shape of the teeth tips, in order to assist with insertion of the former into the slots.

The former is preferably arranged to be wound with the coil, for example using a winding machine. For example, the former may be arranged such that multiple turns of wire can be wound onto it in order to form the coil. Alternatively the coil may be wound separately and then placed into the former.

Preferably the former is arranged to provide an insulating barrier between the coil and the slot, once inserted. This may allow the former to replace the insulation paper which might otherwise be provided inside the slots. Thus the former itself may prevent the coil from making direct contact with the slots, thereby preventing short circuits between the coil and the slots.

Preferably the former is arranged to at least partially enclose the coil for at least part of its length. For example, the former may be arranged to at least partially enclose at least that part of the coil which is to be inserted into the slots (for example, the side windings). For example, that part of the coil which is to be inserted into the slots may be enclosed on at least three sides. This can allow the former to provide an insulating barrier between the coil and the slot, once inserted. Furthermore, the former may act as a barrier between the coil and the slot during insertion, which may help to prevent damage to the coil. If desired, the former may enclose more than three sides, for example, the whole of the coil, for at least part of its length.

In order to at least partially enclose the coil, the former may comprise an interior side wall, a base and an exterior side wall. The interior side wall may extend around at least part of the inside of the coil, the exterior side wall may extend around at least part of the outside of the coil, and the base may extend around at least part of the lower surface of the coil. Thus the former may have a substantially U-shaped cross-section for at least part of its length.

In order to facilitate winding of the coil onto the former, the former may comprise a side wall which can be folded down for winding. For example, the former may be arranged such that the exterior side wall can be folded down. For example, the exterior side wall may be folded down into substantially the same plane as the base. This may make it easier for the coil to be wound on the former using, for example, a winding machine. Preferably the side wall can be folded back up next to the coil, for insertion of the former and coil into the slots.

The winding former is preferably formed from an insulating material with a certain degree of malleability. For example, the former may be formed from a plastic, such as a polymer, or a resin impregnated material, or any other suitable material. This may help with insertion of the former into the slots without damaging the slots, and allow the former to provide an insulating barrier.

According to another aspect of the present invention there is provided a winding set comprising a coil and a winding former in any of the forms described above.

The coil preferably comprises multiple turns of wire. The wire may be, for enamel coated copper wire, or any other suitable wire. The coil is preferably formed by winding multiple turns of wire onto the former, for example using a winding machine.

Preferably an unsupported end winding of the coil is bendable out of the plane of the winding former. This may facilitate axial insertion of the winding set into the slots.

According to another aspect of the invention there is provided a stator for a rotating electrical machine, the stator comprising a stator core with a plurality of stator slots, and a plurality of winding sets in any of the forms described above inserted in the stator slots. Preferably the winding sets form distributed stator windings.

According to another aspect of the invention there is provided a method of installing distributed windings in a rotating electrical machine, the method comprising winding a coil for a distributed winding on a former, and inserting the coil and former as a unit into slots in the electrical machine.

In a preferred embodiment the method is for installing distributed windings in the stator of a rotating electrical machine, and thus the slots may be stator slots. However the present method may also be used, for example, for the installation of rotor windings.

The method preferably comprises inserting the coil and the former axially into the slots. This may allow the coil to be inserted with minimum disruption to the placement of wires in the coil, which may help to achieve a higher slot fill.

The method may comprise reshaping an end winding of the coil so as to sit clear of the slots during axial insertion of the former and the coil into the slots. For example, the end winding may be bent so as to exit the slots in a radial direction during insertion. The method may also comprise reshaping the end winding following insertion so as to exit the slots at least partially in an axial direction. Preferably the end winding which is reshaped is unsupported by the former.

The method may comprise winding multiple turns of wire onto the former, for example, using a winding machine.

Preferably one side of the former is folded down during winding. The side of the former may then be folded up for insertion of the former and coil into the slots.

Preferably a former and a coil form a winding set. The method may comprise inserting a plurality of winding sets to form distributed windings. A plurality of winding sets may be inserted simultaneously. This may allow certain distributed winding configurations, such as lapped winding configurations, to be achieved.

In the present specification terms such as “circumferential”, “radial” and “axial” are generally defined with reference to the axis of the rotating electrical machine about which the rotor rotates.

Features of one aspect of the invention may be provided with any other aspect. Apparatus features may be provided with method aspects and vice versa.

Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows schematically parts of an apparatus used to wind a coil for a distributed winding in an embodiment of the present invention;

Figure 2 shows a winding set comprising a former and a coil after removal from a winding machine;

Figure 3 shows a winding set and part of a stator core prior to insertion of the winding set;

Figure 4 shows part of the stator core with the winding set partially inserted;

Figure 5 shows part of the stator core with a winding set near full insertion; Figure 6 shows in more detail part of the stator core and winding set; Figure 7 shows part of the stator core after insertion of the winding set; and

Figure 8 is an end view of part of the stator core after insertion of a winding set

It is broadly estimated that 90% of all electric motors which are currently manufactured are induction motors, requiring conventional distributed stator winding patterns and cores. Induction motors and high speed alternators can typically only use distributed windings as they require a relatively good spatial sinusoidal magneto-motive force free of large harmonics to ensure efficient motor operation. Concentrated coils, (or tooth coils) typically have too much harmonic content which would interact with the rotor cage. It is also known that distributed winding have lower operational vibrations when compared to concentrated wire winding patterns, as well as improved thermal efficiency.

Conventional stator core assemblies consist of a pre-built stator core made from steel laminations with slots stamped into the inner circumference. These slots are typically lined using an insulation paper which prevents the coils from making direct contact with the steel core - preventing shorting between the copper and steel during the motor’s operation. Depending on the slot closure design, the coils are commonly formed by tumble winding multiple turns of enamel coated copper wire onto a winding former. These windings are then removed from the winding tooling and placed loosely onto “draw-in” tooling that pulls the coils through the stator core whilst pushing them down through the slot opening.

Coated wire windings are common for electrical machines up to 2MVA as they have a number of advantages over the alternative winding such as bar windings. Wire is the cheapest form of conductor and allows for a high number of turns to be achieved for each individual coil and with the fewest processing steps. It is possible to produce a wide range of winding designs whilst maintaining the optimal semi-closed slot configuration for machine stators.

Tumble winding can produce very dense windings under tension. Tumble winding can also produce concentric and lapped coil designs. However there are issues associated with wire coils and their method of assembly. These include high frictional forces being placed onto the coils by the insertion tooling which can damage the enamel coating, loose coils becoming damaged during transfer between the winding tooling to the insertion tooling, wires from separate coil turns being inadvertently mixed together, low slot fill (~30-50%) and high labour requirements. Furthermore, once removed from the winding former, all tension and placement of the wires is lost, making the process of producing high density coils impossible. Full automation is not normally possible for large alternator or motor stators with a semi-closed slot configuration due to the lack of control over the flexible, loose coils, and the high insertion forces placed onto the windings and the insertion tooling itself.

Embodiments of the present invention relate to techniques for installing distributed windings into slots in the stator of a rotating electrical machine. In one embodiment, a winding former is used to contain the tumble wound coils from the point of winding to their insertion into a stator core. The former removes all loose windings from the handling process and allows them to be axially inserted into a skewed stator core without the need for conventional insertion tooling. Once inserted, the former then acts as the slot insulation system.

Figure 1 shows schematically parts of an apparatus used to wind a coil for a distributed winding in an embodiment of the present invention. Referring to Figure 1, the apparatus comprises a winding machine, indicated generally by reference numeral 10. The winding machine 10 comprises winding machine fixtures 11, 12, 13, 14 which are arranged to rotate about an axis 15. A U-shaped winding former 20 is located on the winding fixtures 11, 12, 13, 14.

In operation, the winding fixtures and the winding former are rotated about the axis 15, as indicated by the arrows. As the winding fixtures and the former rotate, a coil 22 is wound onto the former. Two side windings 23, 24 and one end winding 25 are wound onto the former 20, while the other end winding 26 is wound directly onto the fixture 14. Once the complete coil has been wound, the former 20 and the coil 22 are removed as a unit from the winding machine.

Figure 2 shows schematically a winding set comprising the former 20 and coil 22 after removal from the winding machine. As can be seen from Figure 2, the former 20 supports the two side windings 23, 24 and the end winding 25, leaving the end winding 26 unsupported. The unsupported end winding 26 contains coil tails 27, 28 which are used to wire up the stator after all coils have been inserted.

In the arrangement of Figures 1 and 2, the former 20 has an interior side wall 30, a base 32, and an exterior side wall 34. The interior side wall 30 and exterior side wall 34 each include lugs 36, 38 on their outside edges adjacent to the unsupported end winding 26.

During winding, the exterior side wall 34 is folded down, to allow the winding turns to be wound on the former. After winding, the exterior side wall 34 is folded up so that it is adjacent to the coil. In this way, the former encloses three sides of the coil, leaving the top surface exposed. The side wall 34 includes slots 35 to facilitate folding up of the side wall. The former may also have a score mark or flexible joint along the interface between the base and the exterior side wall.

The winding set comprising the former 20 and the coil 22 is designed for axial insertion into the stator slots. In order to achieve this, the unsupported end winding 26 is first bent upwards so that it can clear the stator slots.

Figure 3 shows schematically the winding set and part of the stator core 40 prior to insertion of the winding set. Referring to Figure 3, the exterior wall 34 of the former 20 is folded up against the side of the coil 22. The former thus forms a U-shaped channel which extends around the two side windings 23, 24 and the end winding 25, leaving an exposed top surface as well as the exposed end winding 26. The exposed end winding 26 is bent upwards through an angle of approximately 90°. The exposed end winding 26 is partially supported by the lugs 36, 38 on the outside edges of the interior side wall 30 and exterior side wall 34.

Figure 4 shows schematically part of the stator core with the winding set partially inserted. Referring to Figure 4, the stator core 40 comprises teeth 42 defining stator slots 44. The exposed end winding 26 is bent upwards sufficiently to sit clear of the stator slots 44. This allows the complete winding set, including former 20 and coil 22, to be inserted axially into the slots 44 in the stator core 40. Figure 5 shows part of the stator core with the winding set near full insertion.

Figure 6 shows in more detail part of the stator core and winding set as the end winding 26 exits a stator slot 44. Referring to Figure 6, the stator includes tooth tips 46 at the ends of the teeth 42. The lugs 36, 38 are shaped so as to conform to the shape of the tooth tips 46. The lugs 36, 38 prevent the wires in the exposed end winding 26 from contacting the stator core 40 during insertion of the winding set into the stator core.

Figure 7 shows part of the stator core with the fully inserted winding set. Once the winding set is fully inserted, the exposed end winding 26 can be re-shaped if desired, for example so as to extend axially out of the slots.

Following insertion of the winding set, other winding sets can be inserted in order to form distributed stator windings. In each case the end windings and the former are shaped so as to clear other inserted coils.

The techniques described above can be used with various different types of distributed winding configurations, such as single layer, double layer, double layer nonconcentric lapped and double layer fully (concentric) lapped. Some of the possible winding configurations are summarised below. 1. Single layer windings: as single layer of winding is placed within each slot of the machine. 2. Double layer windings: the winding pattern consists of two discrete layers within each slot. Each coil group is inserted into the stator so that both inserted sides of each winding end up on the same layer - i.e. either on the top or bottom layer. 3. Non-concentric lapped (partially lapped) winding: the first group of windings are drawn into the machine and placed fully on the bottom layer. Further coils are inserted and overlap the first group - with one side on the top layer and the other on the bottom layer. All subsequent coils are drawn into the core, continuing this pattern with one side on the top and the other in the lower layer. The final group of coils are placed fully on the top layer as it is far easier to do so. This process, like the previous two, only requires each group of coils to be handled once during insertion. 4. Fully concentric lapped windings: the process is the same as the partially lapped coils but when it comes to inserting the final set of windings, the first groups of windings are partially removed to allow the final coils to have one side placed on the lower winding layer. This process is usually done by hand. Having partially removed the first coils through the slot openings, the final group is inserted before the initial coils are replaced back into their slots, now on the top layer. This completes the lapped pattern - every coil now has one layer side on each winding layer.

The processes for inserting single layer windings, double layer windings and partially lapped windings are all very similar, as none of them creates an enclosed space in the lower part of the slot. This allows for coils to be inserted one at a time or all at once - depending amongst other things on the size of the machine.

In order to insert a fully concentric lapped pattern, one option is for all of the prewound, former mounted coils to be inserted at the same time. The winding former described above may facilitate this process as the coils are pre-shaped to fit into the slots and fit between the stator tooth tips, thus reducing the forces placed on the tooling and the coils. Alternatively, it may be necessary to partially remove one set of windings prior to inserting the final set of windings, in the way described above.

Figure 8 is an end view of part of the stator core after insertion of a winding set in one possible winding configuration. As can be seen from Figure 8, the former 20 and coil 22 are shaped such that the side winding 24 is at the bottom of one slot, while the side winding 23 is at the top of another slot. This arrangement allows space for another coil to be inserted into each of the slots, in order to provide a lapped winding arrangement.

The former described above provides a number of advantages, including the following: 1. It helps retain the coil’s placement accuracy after it is removed from the winding machine. This can allow a higher slot fill to be achieved. 2. It replaces the steel to copper contact during the insertion process. This can help to avoid damage to the wires in the coil. 3. It acts as an insulating barrier between the conductors and the steel core in place of conventional slot liners.

The former may be made of any suitable material having the required strength, insulating properties, and malleability. It has been found that a suitable material is a plastic polymer or a resin impregnated material.

The steps involved in winding and inserting the coil in one embodiment are summarized below. 1. Firstly, loose wire ends are pulled from a wire reel and attached to the winding machine fixture. The number of wires attached to the winding machine in parallel is dependent on the electrical machine specifications. 2. Based on pitch requirements, the winding fixtures can be adjusted to match. The U-shaped formers are then placed on the fixtures - one for each coil within the coil group. 3. The wires are pulled onto the rotating former under tension until the coil pattern is complete. After winding the coil is folded closed to contain the coils whilst they are still retained by the winding fixture. Alternatively the coils can be removed from the fixture and be placed directly into the former from above. 4. The wire is insulated by an enamel coating which provides the insulation between the wires within each coil. The U-shaped former replaces the traditional slot insulation (e.g., slot liners that provide the proper insulation for the electric machine's voltage rating). The loose end winding is shaped either during winding or immediately after winding to both sit clear of the stator core and to ensure that the wires which pass between the stator teeth are suitably placed so no fictional forces are placed on them during insertion. 5. All conductor elements of one complete winding set are inserted axially into the stator slots, creating one or two layers of windings (or more). The former lugs act as physical protection between the conductors and the steel core tooth tips. These lugs can be used independently or in conjunction with conventional draw in tooling. By consolidating the coils prior to insertion and by protecting them with the insertable former it is also possible to use the body of the coils to push them through the core instead of pulling them in using the end windings. 6. After insertion, the loose end winding is reshaped in order to ensure the optimal shape for cooling, and to allow the coil tails to be wired together according to the product specifications.

It will be appreciated that the embodiments above have been described by way of example only, and various modifications would be apparent to the skilled person. For example, the end winding could be not necessarily contained but merely shaped and held in place by the former. The former may or may not provide structural rigidity as the coils themselves may have some structural rigidity. The containment given by the former may be purely mechanical, purely due to resin or a combination of resin and mechanical containment. Furthermore, the former could be made out of any suitable insulating material. In addition, the present invention is not limited to the installation of stator windings, and could be used for example to install rotor windings.

Claims (38)

1. A winding former for forming a coil for use as a distributed winding in a rotating electrical machine, wherein the winding former is arranged to be inserted into slots in the electrical machine together with the coil.

2. A winding former according to claim 1, wherein the slots are slots in the stator of the electrical machine.

3. A winding former according to claim 1 or 2, wherein the winding former is arranged to be inserted into two slots which are not adjacent to each other.

4. A winding former according to any of the preceding claims, wherein the winding former is arranged for axial insertion into the slots.

5. A winding former according to any of the preceding claims, wherein the former is arranged to support at least two side windings and one end winding of the coil.

6. A winding former according to any of the preceding claims, wherein the winding former is substantially U-shaped.

7. A winding former according to any of the preceding claims, wherein the winding former is arranged such that one end winding of the coil is unsupported by the former.

8. A winding former according to claim 7, wherein the winding former is arranged such that the unsupported end winding can be re-shaped.

9. A winding former according to claim 8, wherein the winding former is arranged such that the unsupported end winding can be reshaped so as to clear the slots during axial insertion of the former and the coil into the slots.

10. A winding former according to any of claims 7 to 9, comprising a lug for protecting the unsupported end winding as it is inserted into the slots.

11. A winding former according to claim 10, wherein the slots are defined by teeth having teeth tips, and the lug is shaped so as to correspond to the shape of the teeth tips.

12. A winding former according to any of the preceding claims, wherein the former is arranged such that multiple turns of wire can be wound onto it.

13. A winding former according to any of the preceding claims, wherein the former is arranged to provide an insulating barrier between the coil and the slot.

14. A winding former according to any of the preceding claims, wherein the former is arranged to at least partially enclose the coil for at least part of its length.

15. A winding former according to claim 14, wherein the former is arranged to at least partially enclose at least that part of the coil which is to be inserted into the slots.

16. A winding former according to any of the preceding claims, wherein the former comprises an interior side wall, a base and an exterior side wall.

17. A winding former according to any of the preceding claims, wherein the former has a substantially U-shaped cross-section for at least part of its length.

18. A winding former according to any of the preceding claims, wherein the former comprises a side wall which can be folded down.

19. A winding former according to claim 18, wherein the side wall can be folded back up.

20. A winding set comprising a coil and a winding former according to any of the preceding claims.

21. A winding set according to claim 20, wherein the coil comprises multiple turns of wire.

22. A winding set according to claim 20 or 21, wherein an unsupported end winding of the coil is bendable out of the plane of the winding former.

23. A stator for a rotating electrical machine, the stator comprising a stator core with a plurality of stator slots, and a plurality of winding sets according to any of claims 20 to 22 inserted in the stator slots.

24. A stator according to claim 23, wherein the winding sets form distributed stator windings.

25. A method of installing distributed windings in a rotating electrical machine, the method comprising winding a coil for a distributed winding on a former, and inserting the coil and former as a unit into slots in the electrical machine.

26. A method according to claim 25, wherein the method is for installing distributed windings in a stator of a rotating electrical machine, and the slots are stator slots.

27. A method according to claim 25 or 26, wherein the method comprises inserting the coil and the former axially into the slots.

28. A method according to any of claims 25 to 27, wherein the method comprises reshaping an end winding of the coil so as to clear the slots during axial insertion of the former and the coil into the slots.

29. A method according to claim 28, further comprising reshaping the end winding following insertion so as to exit the slots in an axial direction.

30. A method according to claim 28 or 29, wherein the end winding which is reshaped is unsupported by the former.

31. A method according to any of claims 25 to 30, the method comprising winding multiple turns of wire onto the former.

32. A method according to claim 31, wherein one side of the former is folded down during winding.

33. A method according to claim 32, wherein the side of the former is folded up for insertion of the former and coil into the slots.

34. A method according to any of claims 25 to 33, wherein a former and a coil form a winding set.

35. A method according to claim 34, the method comprising inserting a plurality of winding sets to form distributed windings.

36. A method according to claim 34 or 35 wherein a plurality of winding sets are inserted simultaneously.

37. A winding former substantially as described herein with reference and as illustrated in the accompanying drawings.

38. A method of installing distributed windings substantially as described herein with reference to the accompanying drawings.