GB817512A - Improvements relating to dynamo-electric machines - Google Patents

Abstract

817,512. Cooling dynamo-electric machines. ENGLISH ELECTRIC CO. Ltd. Feb. 10, 1956 [Feb. 18, 1955], No. 4912/55. Class 35. In a totally-enclosed machine, gaseous coolant is circulated in closed circuits including a cooler on the output side of the fan and a second cooler for the coolant after it has traversed the machine from end to end by stator and rotor ducts. Gas leaving the gear-driven blower 38 passes in parallel over two units of the first cooling stage (not shown) in the right-hand half of the machine and part of it reaches the space 46 from which part of it flows axially through ducts 28 in the stator core and conductor slots to the space 57 where it is joined by other gas streams and passes in parallel to the two circumferentially spaced units 15 (one shown) of the second cooler stage before returning to the blower via holes 60 in the core-supporting rings 61 and pipes 59. Another part of the gas from space 46 leaks under the baffle 37 and flows along the " air gap " to space 57, the remainder of the gas from space 46 passing into the interior of the rotor end winding shroud 31 at the right-hand end of the machine where there is a further split up, some traversing ducts in the slot portions of the conductors until it escapes into the " air gap " by passages 56, and some flowing around the end winding overhangs to reach outlets 34 at the right-hand end of the rotor periphery. The path taken by the gas within the shroud 31 is similar to that shown in Fig. 3 for the left-hand end of the rotor, a partition 52 being provided between the inlets 50, 51 for the end windings and slot portions respectively, members 54 being ducted spacers, the gas in the slot portions of the rotor conductors passing into the " air gap " near the rotor centre. The part of the gas leaving the first stage cooler units which does not pass to the right-hand end of the machine (space 46) traverses pipes 47 leading to space 48 and passes to the rotor inlets 49 at the left-hand end of the rotor then taking the paths shown in Fig. 3 and joining up with the " air gap " gas and that in space 57 to flow to the second-stage coolers. The stator conductors may be in two stacks 17a, 17b separated by insulated tubes for coolant and the slot wedges 23 can be extended to provide axial ducts 26 between the faces of the teeth and additional wedges 25. The wedges 23 can have axial ducts 76 leading at the centre of the rotor to the air gap by radial passages 77 and in that case it may join up with gas reaching the centre of the rotor from the slot portions of the rotor conductors and flow towards both ends of the rotor along the air gap, the gas flowing towards the righteventually getting back to the left-hand end of the machine as described with reference to Fig. 4 (not shown). The layout of the machine could be modified to enable the blower and the gearing linking it to the main shaft to be at the left-hand end of the machine.