https://www.electrical-contractor.net/ubb/Forum7/000234.html I know the above [2003] post by 'Hillbillysawmiller' has been quoted several times recently in parallel threads on this topic, but it's a most impressive commercial use of the 'big motor' method.
With a 200A single-phase supply, HBSM was (is?) running a variety of big wood-mill machines. Starting a 25HP 3-ph. donor with a small single-phase donkey, he then runs up a 40HP 3-phase saw with a 10hp 3-phase donkey-motor, switching it in to his 'main' once up to speed, so is he using a 'donor' as a power source? He has a 20HP resaw, 10HP blower and a variety of 7.5 and 5hp motors on auxilliary machines too. Interestingly, HBSM made several points- that 'capacitor starting' drew big peak start-amperes, which was why he went for donkey-starting; that a colleague sawyer had been 'shut down by the poco' when using a rotary-converter, as this had seriously affected supply volts for several miles around; and that he had little or no problems with voltage drop on the supply side or with switching-in motors once up to rpm.
One nagging doubt I have is; are the 3-phase donor[s] 1- or 2-phasing?- a recipe for motor overheating?
Alan
Moderator, the URL is correct, ?
[This message has been edited by Alan Belson (edited 04-05-2006).]
