GB2076597A

GB2076597A - Securing Windings in an Electrical Rotating Machine

Info

Publication number: GB2076597A
Application number: GB8107617A
Authority: GB
Original assignee: AEI
Current assignee: AEI
Priority date: 1980-05-16
Filing date: 1981-03-11
Publication date: 1981-12-02

Abstract

An electrical rotating machine has a winding comprising a plurality of conductors 1 extending through a slot in a magnetic core 5. The interstices between conductors 1 in the slot and/or between the conductors and the wall of the slot are packed with lengths 7 of insulating material extending through the slot and protruding from each end thereof where they are bound by lengths 9 to form a bundle with the conductors. The insulating lengths may be cords, ropes, tapes or filaments of glass or polyester. The conductors between slots may be bound together to form a bundle, the binding also embracing fitted material 11, packing material 17 and a floating or fixed bracing ring 13 (Fig. 3, not shown). The arrangement may be resin impregnated. The construction avoids chafing of winding insulation due to movement of the windings relative to the magnetic core, in particular in machines designed for operation while submerged in a liquid. <IMAGE>

Description

SPECIFICATION Electrical Rotating Machines This invention relates to electrical rotating machines.

The windings of electrical rotating machines typically consist of conductors extending through slots in a core of magnetic material and comprising a solid or stranded core with an insulating covering, typically of thermoplastics material. In service, problems can arise due to movement of the windings causing chafing and ultimate electrical breakdown of the insulation.

The problem arises especially with electrical rotating machines designed for operation while submerged in a liquid, e.g. water.

It is an object of the present invention to provide an electrical rotating machine wherein this problem is overcome.

According to one aspect of the present invention there is provided an electrical rotating machine having a winding including at least one portion comprising a plurality of conductors extending through a slot in a core of magnetic material with the interstices between the conductors in the slot and/or between the conductors and the wall of the slot packed with lengths of insulating packing material extending through the slot and protruding from each end thereof where they are bound to form a bundle with the conductors.

According to a second aspect of the invention there is provided an electrical rotating machine having a winding comprising a plurality of conductors extending through a series of slots in a core of magnetic material, the portions of the conductors between at least one pair of slots being bound together to form a bundle. The binding preferably also embraces insulating packing material disposed alongside the conductors.

In such an arrangement the binding suitably also embraces a floating or fixed bracing member to provide further support. A block or pad of packing material is suitably disposed between the bracing member and the conductors.

In a machine according to either aspect of the invention, the core, conductors, and associated packing material and support members (if present) are preferably impregnated with a suitable insulating material, e.g. a solventless resin, using for example, a vacuum pressure impregnation process.

It will be appreciated that both aspects of the invention will normally be utilised in a single machine.

One electrical rotating machine will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a view of part of the stator winding of the machine; Figure 2 is a sectional view on the line Il-Il in Figure 1; Figure 3 is a sectional view on the line Ill-Ill in Figure 1; and Figure 4 iilustrates a modification of the winding.

The machine is an electric motor designed for operation while submerged in water.

Apart from the method of securing its stator winding the motor may be of any suitable conventional form.

Referring to Figures 1 to 3, the motor stator winding comprises a plurality of conductors 1 (which may be successive turns of a single conductor) comprising a circular solid metal core provided with a covering of thermoplastics material. The conductors 1 extend through a series of slots 3 in the stator core 5 of the motor, only one such slot 3 being shown in Figure 1.

Between the slots 3 the conductors 1 are bent through 1 80C to form generally semi-circular end portions of the winding.

In each slot portion of the winding lengths 7 of insulating material in the form of cords, ropes, tapes or filaments of glass or polyester extend through the slot 3 alongside the conductors 1 so as to pack the insterstices between the conductors 1 and between the conductors 1 and the wall of the slot 3. At each end of the slot 3 the lengths 7 of insulating material protrude, and the protruding ends are bound up with the conductors 1 using a further length or lengths 9 of the same material to form a compact bundle. The insulating material 7 may be laid through the slot 3 at the same time as the winding conductors 1, or alternatively, drawn through the slot 3 after the winding conductors 1 have been positioned.

At each end portion of the winding, the conductors 1 are wrapped in insulating felted material 11 and bound to a rigid bracing ring 13 using a length or lengths 1 5 of insulating material with a pad 1 7 of insulating material between the bracing ring 1 3 and felt wrapped conductors 1.

The bracing ring 1 3 may, in the completed motor, be floating or secured to the frame (not shown) of the motor.

On completion of the stator winding, the whole stator, is placed in a pressure vessel (not shown) which is then evacuated to remove air and moisture. A solventless resin is then admitted to the vessel to immerse the stator while still under vacuum. After a period, the vacuum is released and a sufficient pressure built up in the vessel to force resin into voids in the stator structure. After a further period the pressure is released and excess resin removed to a storage vessel. The stator is then removed from the pressure vessel and placed in an oven to cure the resin.

In the resulting structure the conductors 1 are firmly secured to the stator core 5 so as to prevent the possibility of movement of the conductors 1 relative to one another or the stator core 5 and so prevent chafing of the conductor insulation.

In the machine described above by way of example the slot 3 is only wide enough to accommodate one conductor. In other machines in accordance with the invention slots of different configuration may be employed, Figure 4 illustrating one such slot 1 9.

Claims

1. An electrical rotating machine having a winding including at least one portion comprising a plurality of conductors extending through a slot in a core of magnetic material with the interstices between the conductors in the slot and/or between the conductors and the wall of the slot packed with lengths of insulating packing material extending through the slot and protruding from each end thereof where they are bound to form a bundle with the conductors.

2. An electrical rotating machine having a winding comprising a plurality of conductors extending through a series of slots in a core of magnetic material, the portions of the conductors between at least one pair of slots being bound together to form a bundle.

3. An electrical rotating machine according to Claim 2 in which the binding also embraces insulating packing material disposed alongside the conductors.

4. An electrical rotating machine according to Claim 2 or Claim 3 in which the binding also embraces a floating or fixed bracing member.

5. An electrical rotating machine according to Claim 4 in which a block or pad of packing material is disposed between the bracing member and the conductors.

6. An electrical rotating machine according to Claim 1 and any one of Claims 2 to 5.

7. An electrical rotating machine according to any preceding claim in which the core, conductors and associated packing material and bracing member (if present) are impregnated with a suitable insulating material.

8. An electrical rotating machine according to Claim 7 in which the impregnation is carried out using a vacuum pressure impregnation process.

9. An electrical rotating machine according to any one of the preceding claims, wherein said packing material consists of glass.

10. An electrical rotating machine according to any one of the Claims 1 to 9, wherein said packing material consists of a polyester.

11. An electrical rotating machine according to any preceding claim in which said machine is an electric motor designed for operation when submerged in water.

12. An electrical rotating machine substantially as hereinbefore described with reference to the accompanying drawings.