Advanced cooling technology for rotors of high-power low-duty cycle generators using polyalphaolefins

Experimental and numerical studies of heat transfer distribution on rotors of high-power low-duty cycle electrical machines are performed to investigate the temperature distribution across the rotor core and winding insulation that determines the performance of rotor cooling techniques. Studies are performed to verify the selected cooling technique and coolant, and to determine the maximum heat load on the rotor and on the insulation material of the windings. The coolant used is polyalphaolefin (PAO) oil that can be used both as a coolant and lubricant. The boundary conditions investigated in this study are those existing on actual rotors of electric machines. The results show that the maximum temperature in the rotor conductors is found in the windings end turn and the maximum temperature in the insulation material of the rotor conductors could reach high values but still within the allowable maximum temperature limits. Copyright © 2007 John Wiley & Sons, Ltd.