IE851418L

IE851418L - Distribution of cooling gas

Info

Publication number: IE851418L
Application number: IE851418A
Authority: IE
Original assignee: Alsthom Atlantique
Priority date: 1984-06-07
Filing date: 1985-06-06
Publication date: 1985-12-07
Also published as: DE3567336D1; MX163031B; CA1241051A; EP0166990B1; IN163386B; FR2565741B1; FR2565741A1; ZA854347B; BR8502713A; MA20447A1; EP0166990A1; EP0166990B2; KR860000732A; ATE39796T1; GR851381B; DZ788A1; IE56594B1; KR930001775B1

Abstract

1. A device for distributing cooling gas under a retaining sleeve (3) at one end of the excitation winding of a turbo- alternator rotor, comprising a cylinder of electrically insulating material (6) disposed immediately under the end of the winding, provided with gas admission windows (7) between the coils of this winding, as well as radial (8) and circumferential partitions (9) disposed between the cylinder of insulating material and the rotor shaft (1) and dividing the annular orifice between the cylinder of insulating material and the shaft into radial compartments for cold gas inlet (10) and for hot gas outlet (11), both being connected to inlet and outlet channels disposed between the ends of the coils, characterized that the gas admission and exhaust channels are themselves connected to channels inside the conductors via side openings of the latters, and that the exhaust channels are connected to a single outlet compartment in the center of each pole.

Description

% The present invention relates to apparatus for distributing cooling gao under a retaining sleeve at one end of the excitation winding of a turbo-alternator rotor, the apparatus comprising a cylinder of electrically insulating material disposed immediately under the end of the winding, said cylinder being provided with gas admission windows situated between the coils of said winding, the apparatus further including radial and circumferential walls disposed between the cylinder of insulating material and the rotor shaft to divide the annular orifice between the cylinder of insulating material and the shaft into radial compartments for cold gas inlet and for hot gas outlet, said compartments being connected to inlet and outlet channels disposed between the ends of the coils.

Cooling gas has already been distributed under the retaining sleeves at the ends of such excitation windings by causing said gas to penetrate into said ends in the space lying between the coils of the winding and the shaft per se, then into ventilation channels machined in the thickness of the conductors and directed axially, via orifices situated in the sides of the coils near their front ends. After cooling each conductor, the gas leaves via radial channels passing through the conductors, and then through orifices in the slot-closing wedges beyond the ends of the retaining sleeves.

Such cooling apparatus requires long axial cooling paths inside the conductors, thus cooling the ends less well than in the portion inside the slots, and consequently gives rise to considerable temperature differences between the ends of said portion.

Cooling gases also have also been distributed under retaining sleeves at the ends of an excitation winding by causing the gas to circulate in radial manifold compartments for gas inlet and outlet, said compartments being machined in the shaft. Each of these compartments is in communication with 3 a corresponding space between the coils of the winding, which space serves either as a gas inlet or as a gas outlet. The conductors are cooled transversely via multiple transversal grooves thereon, with the cold gas entering said grooves from 5 one side of the conductors and leaving via the opposite side. The gas heated by contact with the conductors flows into a lower outlet compartment and moves axially into an annular space between the sleeve-carrying plate and the largest coil. The hot gas is removed from the end of the sleeve by an 10 extractor fan.

This apparatus requires expensive machining of the rotor shaft in order to form the inlet cooling channels, together with an outlet manifold system at the end under the retaining sleeve, including an extractor fan at said end. 1 5 British patent specification N* 805,878 proposes cooling gas distribution apparatus comprising a cylinder of electrically insulating material under the end of the winding and pierced by a plurality openings connected to multiple admission and exhaust ducts for cooling gas. This makes the structure of the 20 apparatus complex and fabrication thereof expensive. Another known device is described in Patent Publication FR-A- 1 100 805. ;I ;Preferred embodiments of the present invention provide cooling gas distribution apparatus which gives rise to short cooling gas flow paths in the ends of the rotor, and ensures highly uniform temperature in the coils of the excitation winding, thereby avoiding the appearance of hot points, while nevertheless being of simple structure and simple to fabricate. ;According to the invention there is provided apparatus for distributing cooling gas under a retaining sleeve at one end of the excitation winding of a turbo-alternator rotor, the apparatus comprising a cylinder of electrically insulating material disposed immediately under the end of the winding, said cylinder being provided with gas admission windows situated between the coils of said winding, the apparatus further including radial and circumferential walls disposed between the cylinder of insulating material and the rotor shaft to divide the annular orifice between the cylinder of insulating material and the shaft into radial compartments for cold gas inlet and for hot gas outlet, said compartments being connected to inlet and outlet channels disposed between the ends of the coils, the gas admission and exhaust channels being themselves connected to channels inside the conductors via side openings through the conductors, and whereby the exhaust channels are connected to a single outlet compartment in the center of each pole. ;The invention preferably includes at least one of the following characteristics: ;At least some of the hot gas outlet compartments are connected to exhaust slits leading to the air gap in the slotted portion of the rotor; ;Said exhaust slits are formed by milling slots in the slotted portion of.the rotor close to the center of a pole; ;At least some of the channels inside the conductors at the ends of the winding are extended by channels inside the conduc-5 tors in the rotor slots, in communication with radial orifices opening out into the air gap through the slot-closing wedges; ;The radial cold gas admission compartments are connected to slot-less channels which open out via radial windows between the rectilinear portions of the winding coils which are 10 provided with lateral admission openings to their channels, and the channels inside the portions of the coils perpendicular to the rotor axis open out into admission windows in the radial compartments for hot gas outlet; ;The channels inside the conductors in the vicinity of the 1 5 slotted portion of the rotor extend beyond the edge of the end retaining sleeve, and open out into the air gap via radial channels passing through the slot-closing wedges; ;The end coils include transverse grooves, the cooling gas passing channels in said coils are perpendicular to their axes, 20 the central zones of the coils include admission windows in radial outlet compartments which are themselves connected to exhaust slits in the slotted portion of the rotor leading to the air gap, and the near zone of the slots in the slotted portion of the rotor include both channels for allowing the gas 2

Claims

1. / Apparatus for distributing cooling gas under a retaining sleeve at one end of the excitation winding of a turbo-alternator rotor, the apparatus comprising a cylinder of 5 electrically insulating material disposed immediately under the end of the winding, said cylinder being provided with gas admission windows situated between the coils of said winding, the apparatus further including radial and circumferential walls disposed between the cylinder of insulating material and 1 0 'the rotor shaft to divide the annular orifice between the cylinder of insulating material and the shaft into radial compartments for cold gas inlet and for hot gas outlet, said compartments being connected to inlet and outlet channels disposed between the ends of the coils, the gas ^ -* admission and exhaust channels being themselves connected to channels inside the conductors via side openings through the conductors, and whereby the exhaust channels are connected to a single outlet compartment in the center of each pole. 20

2. / Apparatus according to claim 1, wherein at least some of the hot gas outlet compartments are connected to exhaust slits leading to the air gap in the slotted portion of the rotor-

3. / Apparatus according to claim 2, wherein said exhaust slits are formed by milling slots in the slotted portion of the rotor 25 close to the center of a pole.

4. / Apparatus according to claim 1, wherein at least some of the channels inside the conductors at the ends of the winding are extended by channels inside the conductors in the rotor slots, in communication with radial orifices opening out into the air 30 gap through the slot-closing wedges.

5. / Apparatus according to claim 1, wherein the radial cold gas admission compartments are connected to slot-less channels which open out via radial windows between the rectilinear IS portions of the winding coils which are provided with lateral admission openings to their channels, and the channels inside the portions of the coils perpendicular to the rotor axis open out into admission windows in the radial compartments for hot 5 gas outlet.

6. / Apparatus according to claim 5» wherein the channels inside the conductors in the vicinity of the slotted portion of the rotor extend beyond the edge of the end retaining sleeve, and open out into the air gap via radial channels passing through 10 the slot-closing wedges.

7. / Apparatus according to claim 1, wherein the end coils include transverse grooves, and wherein the cooling gas passing channels in said coils are perpendicular to their axes, the central zones of the coils include admission windows in radial 15 outlet compartments which are themselves connected to exhaust slits in the slotted portion of the rotor leading to the air gap, and the near zone of the slots in the slotted portion of the rotor include both channels for allowing the gas to flow between the conductors and the slot insulation, opening out 20 into exhaust orifices through the slot-closing wedges and leading to the air gap, and also circular channels opening out into a radial compartment for hot gas outlet.

8. / Apparatus according to claim 1, wherein the end conductors perpendicular to the axis of the rotor include transverse 2 5 grooves, and the conductors close to the slots in the slotted portion of the rotor include internal channels, and alternate cold gas admission and hot gas exhaust windows leading to an outlet compartment are interposed between the conductors which are perpendicular to the axis of the rotor, the conductors 30 close to the slots in the slotted portion of the rotor including lateral cold gas admission windows to the internal channels and in communication with radial exhaust channels leading to the air gap beyond the edge of the end retaining sleeve, and the channels between the end vrindings perpendicular 13 to the axis of the rotor are separated in a sealed manner from the channels between the conductors close to the slots of the slotted portion of the rotor.

9. / Apparatus according to claim 1 for distributing cooling gas under a retaining sleeve at one end of the excitation winding of a turbo-alternator rotor substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. Dated this the 6th day of June, 1985 F. R. KELLY & CO. Dublin 4. EXECUTIVE