Patent EA-001129-B1 (EA)
Title: Rotary electric machine with radial cooling
Inventor: LEIJON MATS
IPC: H02K1/20
Filed: 1997-05-27
Abstract: 1. A rotating electric machine, comprising a stator (1) wound with a high-voltag e cable and provided with stator teeth (4) extending radially inwards from an outer yoke portion (5), characterized in that the machine comprises a winding comprising an insulation system including at least two semi-conducting layers, each layer constituting essentially an equipotential surface and also including solid isolation disposed therebetween, and that at least one stator tooth (4) is connected to at least one cooling tube (18) running radially  in the stator tooth (4) and connected to a cooling circuit (34) in which coolant (36) is arranged to circulate and that the cooling is arranged to take place over at least most of the axial extension of the stator tooth (4). 2. A machine as claimed in claim 1, characterized in that at least one of the layers has substantially the same coefficient of thermal expansion as the solid insulation. 3. A machine as claimed in any of claims 1-2, characterized in that the cooling tube (18) is arranged to extend from the outer yoke portion (5) in through a cooling clamp tooth (25) and at the tip of the cooling clamp tooth (25) passes over to the tip of the next cooling clamp tooth (25) and then again out through this cooling clamp tooth (25) to the outer yoke portion (5), forming a cooling tube loop. 4. A machine as claimed in any of claims 1-3, characterized in that the cooling tube (18) is arranged to extend from the outer yoke portion (5) in through a cooling clamp tooth (25) and at the tip of the cooling clamp tooth (25) turn and passes back out through the said cooling clamp tooth (25) to the outer yoke portion (5), forming a cooling loop (21). 5. A machine as claimed in either of claim 3 or claim 4, characterized in that cooling tube loops (21) are arranged in at least one cooling clamp (19) of substantially identical shape as a stator cross section. 6. A machine as claimed in claim 5, characterized in that cooling tubes (18) are arranged to be cast in the cooling clamp (19). 7. A machine as claimed in claim 6, characterized in that the axial distance between the cooling clamps (19) is maximum 200 mm. 8. A machine as claimed in any of claims 3-7, characterized in that the cooling tube loop (21) is provided with at least one beam (30) arranged in the loop. 9. A method of cooling a rotating electric machine provided with high-voltage stator windings as claimed in claim 1, characterized in that the stator is cooled by a coolant (36) being caused to circulate in a cooling circuit (34) through cooling ducts running radially through the stator teeth (4). 10. A method as claimed in claim 9, characterized in that the coolant (36) is caused to circulate in a closed circuit which passes through a heat exchanger (41) cooling the circuit (34) with water from a water reservoir. 11. A machine as claimed in any of claims 1-8, characterized in that the potential of said first layer is substantially equal to the potential of the conductor. 12. A machine according to claim 11, characterized in that said second layer is arranged to constitute substantially an equipotential surface surrounding said conductor. 13. A machine according to claim 12, characterized in that said second layer is connected to a predetermined potential. 14. A machine according to claim 13, characterized in that said predetermined potential is earth potential. 15. A machine according to any one of the claims 11-14, characterized in that at least two adjacent layers have substantially equal thermal expansion coefficients. 16. A machine according to any one of the claims 1-8 or any one of the claims 11-15, characterized in that said current-carrying conductor comprises a number of strands, only a minority of said strands being non-isolated from each other. 17. A machine according to any one of the claims 1-8 or any one of the claims 11-16, characterized in that each of said three layers is fixed connected to adjacent layer along substantially the whole connecting surface. 18. A machine having a magnetic circuit for high voltage comprising a magnetic core and a winding, characterized in that said winding is formed of a cable comprising one or more current-carrying conductors, each conductor having a number of strands, an inner semiconducting layer provided around each conductor, an insulating layer of solid insulating material provided around said inner semiconducting layer, and an outer semiconducting layer provided around said insulating layer. 19. A machine according to claim 18, characterized in that said cable also comprises a metal shield and a sheath.