Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1983-01-06
1985-01-29
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 51, H02K 346
Patent
active
044968701
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates generally to the field of electrical machine engineering and, more particularly, to arrangements for supporting stator end windings of electrical machines.
The invention can most advantageously be used in high-power turbogenerators.
DESCRIPTION OF THE PRIOR ART
Supporting of the stator end windings of a high-power electrical machine is one of the most severe problems of current electrical machine engineering, since such end windings operate under unfavorable conditions of strong and variable electromagnetic forces and thermal strain.
The main damage factor for the stator end windings is electromagnetic forces which give rise to vibrations of the end windings, resulting in damage of the soldered winding joints as well as in abrasion of its insulation, and in damage of the copper conductors due to fatigue.
In order to provide a substantial increase in the support reliability of the stator end windings, it is necessary to achieve a minimum level of vibrations of the end windings, while keeping a possibility of their axial displacement under thermal strain.
Known in the prior art is an arrangement for supporting stator end windings of an electrical machine, disclosed in the FRG Pat. No. 1,214,773, Cl.21 d.sup.1, 54, published 1963. This arrangement comprises a clamping plate having a projecting portion, and an insulating ring tightly embracing the end windings. The projecting portion comprises a number of brackets fitted with guides, disposed around the outer periphery of the insulating ring, and embracing the latter, the insulating ring together with the end windings being capable of moving along the bracket guides in an axial direction under thermal strain of the electrical machine stator winding.
However, in the course of the electrical machine operation, clearances between the insulating ring and the bracket guides inevitably occur as a result of different thermal strain of its structural elements, whereby rigid connection between the insulating ring and the brackets is lost. This gives rise to an increased level of vibration of the end windings, thereby decreasing the support reliability of vibration of the end windings.
There is also known an arrangement for supporting stator end windings of an electrical machine (cf. the British Patent No. 1,539,707, Int. Cl. H02K 3/50, published 1979), which comprises a clamping plate with a projecting portion, an insulating ring tightly embracing the end windings, resilient strips disposed on the outer surface of the insulating ring and spaced around the periphery thereof. Arranged between the projecting portion of the clamping plate and the resilient strips are means adapted for pressing the resilient strips against the insulating ring in a radial direction and being in contact with the projecting portion.
The resilient strips are made of rubber exhibiting a high rigidity in a radial direction. Due to a low shear modulus of the rubber, the resilient strips features a low rigidity in axial and tangential directions. This makes it possible to provide an axial displacement of the insulating ring together with the end windings relative to the projection portion of the clamping plate under thermal expansion of the stator winding.
Again, the provision of the resilient strips as well as the means for pressing them against the insulating ring makes it possible to eliminate clearances between the insulating ring and the projecting portion of the clamping plate, as a result of which the support reliability of the stator end windings is increased as compared with the arrangement described hereinabove.
However, because of a low shear modulus of the rubber used, the resilient strips fail to prevent the insulating ring from axial and tangential displacements relative to the projecting portion of the clamping plate, caused by variable electromagnetic forces induced by electric current in the stator end windings, and the result is an increased level of vibrations of the end windings in the axial and tangential directions, whic
REFERENCES:
patent: 3089048 (1963-05-01), Bahn
Antonov Jury F.
Chernyavsky Vladimir P.
Iogansen Vadim I.
Shapiro Aron B.
Tkachenko Alexei S.
Leningradskoe Proizvodstvennoe Elektromachinostroitelnoe Obiedin
Skudy R.
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