IE56594B1

IE56594B1 - Apparatus for distributing cooling gas under a retaining sleeve at one end of a turbo-alternator rotor excitation winding

Info

Publication number: IE56594B1
Application number: IE1418/85A
Authority: IE
Original assignee: Alsthom Atlantique
Priority date: 1984-06-07
Filing date: 1985-06-06
Publication date: 1991-10-09
Also published as: DE3567336D1; MX163031B; CA1241051A; EP0166990B1; IN163386B; FR2565741B1; FR2565741A1; ZA854347B; BR8502713A; MA20447A1; EP0166990A1; EP0166990B2; KR860000732A; ATE39796T1; GR851381B; DZ788A1; IE851418L; 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 w 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 r 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 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 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 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.

British patent specification N* 805r878 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 apparatus complex and fabrication thereof expensive. Another knew device is described in Patent Publication FR-A- 1 100 805· 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 turbo10 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 25 center of each pole.

I 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; * 0.

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 conduc5 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 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 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, 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 to flow between the conductors and the slot insulation, opening out 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; The end conductors perpendicular to the axis of the rotor 3θ include transverse 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 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 windings perpendicular 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® ρ An embodiment of the invention is described by way of example with reference to the accompanying drawings, in which: t Figure 1 is a partially cut away perspective view of a cooling gas distribution circuit in accordance with the invention; Figure 2 is a view of a portion of a first variant including longitudinal channels inside the windings; Figure 3 is a developed view of a portion of a second variant in which the end coils are grooved, with cooling gas flowing along said grooves, and then either towards a central outlet compartment or else axially between the coils; Figure 4 is a developed view of a portion of a third variant including two distinct gas flow paths, namely an axially path and a path which is transverse to the axis of the rotor; and Figure 5 is an axial section through the axial flow path of the first fraction of the gas in Figure 4® Figure 1 shows the cooling gas distribution circuits under a retaining sleeve at one end of the excitation windings of a turbo-alternator rotor· The rotor comprises a shaft 1, a slotted portion 2 and two end portions bound by retaining sleeves 3 (only one of which is shown in Figure 1). The end windings 4 are extensions of the bars (not visible) in the slotted portion of the rotor and disposed under slot-closing wedges 5· Cooling gas flow is represented by arrows and is delimited by a cylinder of insulating material 6. The gap between said cylinder and the rotor shaft is subdivided by radial walls 8 and circumferential walls 9 into cold gas inlet compartments 10 and hot gas exhaust compartments 11 ® The gas enters via the inlet compartments 10 (arrows 10A) passes through slits 7 cut through the cylinder of insulating material and into channels between the ends of the coils, and then via side openings into internal channels in said windings.

A first portion of said gas flows circumferentially, passing between the windings and then going down through windows (arrows 11 A) opposite stop wedges 12 in the exhaust compartment 11. The gas is distributed on leaving said windows under the end of the retaining sleeve 3 between longitudinal slots 13 milled in the center of a pole in the slotted portion of the rotor, and leaves into the air gap via the ends of said slots.

The second portion of the gas flows longitudinally towards channels inside the ends of the conductors of the slotted portion of the rotor adjacent to the edge of the retaining sleeve, and then leaves into the air gap via radial channels and orifices 14 passing through the slot-closing wedges 5· In Figure 2, the cooling gas arrives between the shaft and the cylinder of insulating material and is distributed via longitudinally elongate radial slits 20 through said cylinder into the windings via one side thereof. A first portion of the gas in the straight portions of the conductors adjacent to the slotted portion of the rotor flows (arrows 21) into channels inside the conductors beyond the edge of the retaining sleeve, and then leaves radially via radial buttonhole-shaped channels in the slots to escape into the air gap via orifices 22 through the slot-closing wedges, as described in greater detail below with reference to Figure 5· A second portion of the gas in the front part of the coils situated under the retaining sleeve flows (arrows 23) into channels inside said front part and escapes via the opposite side of said v/indings into outlet channels 25 therebetween, and then penetrates via radial slots 26 into an exhaust compartment 12A. It is then distributed (arrows 13A) into longitudinal slots milled in the slotted portion of the rotor in the vicinity of a pole, beyond the end of the retaining ring and leaves into the air gap as already mentioned with reference to Figure 1» © This type of cooling for the ends of the coils is preferably associated with axial-radial or radial ventilation of those parts of the straight portions of the conductors which lie in the slots.

In Figure 3 the end windings are fitted with multiple transverse grooves 30. The cooling gas arrives along arrows 31 and is distributed by the elongate radial slots which are either longitudinal 32 or circumferential 33 between the windings, into which it penetrates via one side and from which o it leaves via the opposite side (arrows 3β) into spaces 35 between the conductors. The gas is then exhausted in two different manners: a) In a central zone corresponding to the center of a pole, the hot gas is admitted into the central outlet compartment of the distribution cylinder via radial openings 36» 1+ then escapes via slots milled in the slotted portion of the rotor from the pole into the air gap beyond the retaining sleeve (arrows 37)ϊ b) Xn the zone situated opposite the rotor slots, the hot gas moves axially along the space between the windings towards the Blotted portion of the rotor and splits into two parts. A first part flows along the rotor slot in the space situated between the conductors and the slot insulation. It then leaves into the air gap beyond the retaining sleeve portion via exhaust orifices 14 through the slot-closing wedges. It may also be conveyed towards the slots milled in the center of the pole. A second portion leaves via outlet orifices from the manifold cylinder and is channelled via a second outlet compartment adjacent to the metal of the slotted portion of the rotor. It thus moves tangentially (arrows 39) to the center zone of a pole to escape into the air gap via the abovementioned slots milled in the center of the pole.

This type of ventilation for the ends of the windings may be associated with ventilation for the rectilinear portion of the conductors situated in the slots of the rotor, for taking gas from the air gap or else of the axial-radial type or of the purely axial type.

$ Figure 4 shows apparatus for ventilating the end windings using internal gas paths which are partially on the axis of the conductors and which are partially transversal thereto. The conductors have internal channels on their axes in their axial portions beyond the slots.

On the portions of the conductors which are transversal to the axis of the rotor, there are transversal grooves 40. i The cold gas distributing cylinder distributes the gas into inlet spaces between the windings.

In the straight portions of the conductors, the gas inlets corresponding to the axial channels are situated in the sides of the conductors close to the angle between the axially extending portions and the transverse portions (arrow 41)* The axial channels in the conductors open out into the slots and thence into the air gap via radial exhaust buttonholes 42 located beyond the retaining sleeve, as is described in greater detail below with reference to Figure 5· There are no hot gas outlet channels between the rectilinear portions of the conductors.

Providing that a plurality of conductors may be fed laterally in series with cold gas, the channels between the windings in the front portions of the conductors are alternately inlet zones and outlet zones for gas. This zone is separated from the zone of the rectilinear portions of the conductors by sealing wedges 45 which isolate the two cooling circuits from each other.

The orifices through the distributing cylinder provide cooling gas admission and exhaust. The admission orifices 44 are opposite the rotor slots and the exhaust orifices 45 are in the central zone of the poles.

Once the cold gas has penetrated into the space between the inlet windings it passes through the grooves of the front * portions of the conductors and then runs into the channels therebetween (arrow 46). It passes via the orifices 45 into the exhaust compartment of the distribution cylinder, is channelled (arrows 47) into the space between the last winding and the slotted portion of the rotor and then escapes from the center of a pole into the channels which open out into the air gap (arrows 48) as is described in greater detail with reference to Figure 5.

This type of ventilation may be associated with axial5 radial ventilation or with radial ventilation of the rectilinear portions of the inductor winding of the rotor.

Figure 5 shows the flows of two cooling gas fractions, after cooling the rectilinear portions and the front portions of the conductors, with the gas being exhausted into the air gap through the slot-closure wedges, as applicable to the distribution apparatus described with reference to Figures 2 and 4.

The gas flowing along the axial channels 51 of the conductors under the retaining sleeve 3 passes into radial exhaust channels 52 therethrough, and then passes through the slot-closure wedge 5 via orifices 53.

Channels such as 54 milled in the slotted portion of the rotor serve to exhaust cooling gas from the conductors in the front portion. These channels communicate with radial channels 55 and orifices 56 leading to the air gap.

Claims

1./ Apparatus for distributing cooling gas under a retaining sleeve at one end of the excitation winding of a turboalternator 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.

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 close to the center of a pole.

4. / Apparatus according to claim 1 9 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 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 US 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 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 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 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 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 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 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 windings perpendicular 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 5 gas under a retaining sleeve at one end of the excitation winding of a turbo-alternator rotor substantially as hereini before described with reference to and as illustrated in the accompanying drawings®