Our plant has for steam kilns for drying lumber. We have 11 fans per kiln, each driven by a 15 hp open frame 480v/ 3phase motor. We often suffer motor failures and it is highly suspected that we are getting moisture build-up in the windings. i have been given a suggestion that when the fans are not running for a period of time, we simple run 115vac through 2 of the phases (single phasing without turning the motor). I have been told that 115 may be too much voltage and 24 vac might be better. I can hook the necessary relays up through a PLC and insure when the heaters come on and off, so that is no problem. I simply have no experience in this and was wondering if someone out there may have a recommendation. Is this a common practice? What voltages are typically used? What type of current draw would I expect? Any help would be greatly appreciated.