Patent GB-970728-A (GB)
Title: Liquid-cooled rotor for a dynamo-electric machine
IPC: H02K3/22
Filed: 1961-04-25
Abstract: 970,728. Cooling dynamo-electric machines. GENERAL ELECTRIC C O . April 25, 1961 [April 28, 1960], No. 14925/61. Heading H2A. [Also in Division F4] The rotor of a dynamo-electric machine is cooled by passing a liquid through channels in the rotor conductors from manifolds located beneath and or in the innermost conductors, radial feed tubes being provided between the manifolds and the conductors by-passing the channels in the intervening conductors and electrically isolated from such conductors. Fig. 1 shows a generator in which cooling water passes from a de-aerating and storage tank 15 through a pump 16, a cooler 17, a de-ionizer 18 and a filter 19 to the stator through a pipe 21 and through a further pump 23 to the rotor. The water passes through a channel 11 in the rotor shaft to the rotor (as described later) conductors and returns via a second channel 12 in the rotor shaft and pipe 25 to the storage tank. The rotor also includes a centrifuge (described later) to remove foreign matter from the water. Fig. 4 shows part of one rotor arrangement comprising one stack of turns 48 and a further stack 50 which, although shown cut-away, continues to 55 and on to the other half of the turn. Cooling water is pumped through tube 40 into a chamber 56a which is connected to channels in the separate turns by individual tubes such as 58, the tubes passing through the intervening conductors in a manner illustrated with reference to Figs. 5, 6 and 7 (not shown), which provides electrical insulation and prevents water leakage. The water may pass through individual half turns and be discharged at the opposite end of the rotor through a similar manifold arrangement, or it may pass through 1¢ turns before being discharged at the far end, or as a further alternative, may pass through a single turn, in which case a manifold is provided at one end only, the chamber 56a being divided between inlet and outlet portions (Fig. 10, not shown). Figs. 8, 9, 11 and 15 (not shown) illustrate possible water circuits. The turns are anchored by the wedges 54 to the main body of the rotor and by wedge such as 59, 60 to a lug 43 formed ingegrally with the rotor shaft. Expansion of the rotor conductors is permitted by flexing of the portion of the end turn between the rotor body and the lug. To avoid the difficulty of passing the radial tubes 58 through the cooling ducts in the conductors, the cooling ducts may be arranged alternately at each side of the rotor conductor so that the radial tubes pass through the solid central part of the conductors (Figs. 12, 13 and 14, not shown). The cooling water may alternatively be fed to the central part of the length of the turn as shown in Fig. 16. In this embodiment the turn 184a next to the rotor shaft is enlarged at 193 and is shaped as shown in detail in Figs. 17 and 18, to fit in the bottom of the conductor slot and to provide an enlarged channel. From this portion radial feed tubes 189 pass through into the intervening conductors to the water cooling channel in the individual rotor turns. Fig. 2 shows the end of the rotor of the embodiment in which the cooling liquid is fed into the end of the turns. The end turns are surrounded by a ring 28 which is shrunk on to the rotor and secured by a key 31. The ring, when not rev olv ing, is slightly oval and returns to circular shape when the rotor is revolving to bear upon the lugs, holding the end turns and so help to bear the centrifugal stress. The cooling water inlet is via tube 36 which feeds a centrifugal chamber 35 serving to trap foreign matter. The outlet from the chamber is via passage 34b, chamber 38 and a flexible pipe 39. Water leaking from the rotor turns escapes through a passage 32a into end cap 33. This is provided with a number of peripheral recesses bounded by walls 33b and 33c in which the escaping water is trapped so as to slightly unbalance the rotor. - This is detected by conventional means and indicates the presence of the leak. The trapped water is not sufficient to cause severe unbalance, the excess escaping into a channel 33d. By reducing the pressure in the generator housing the trapped water may be allowed to boil away, in which case operation of the generator can continue and the rate of leakage can be determined by the time taken for the vibration to build up again. The Specification describes the method of assembling the rotor and states that the rotor turns may be formed initially as C- or J-shaped members, two of which are brazed together at the ends to form a complete turn. Specifications 786,725, 834,460, 893,890 and 922,695 are referred to.