Electrical Forum - 208 Volt Motor with 240 Volt Electric

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Subject - 208 Volt Motor with 240 Volt Electric - HELP!
Gauge	I am hoping someone can help me come up with a creative way to solve this problem. I have the option to take for FREE a Rockwell radial arm saw that is currently sitting in the basement of a Museum. However, in looking at the plate on the motor, it says the following: Volts: 208 (NOT 208-230, just straight 208) Amps: 8.7 HP: 3 3 Phase I do NOT have 3 phase electric in my garage, but I have been told that I can buy a Phase Converter to convert single phase electric to 3 phase via either a Rotary or Static Phase Converter. My question has to do with the difference in volts. I have 240 volts coming in from the pole, and without a transformer, 240 in means 240 out. My concern is that I will be overpowering the motor, as it is only rated for 208 volts. I have called 2 Phase Converter companies, an electrician, and the manufacturer of the motor (as listed on the saw - Marathon Electric. Mfg. Co.) So far this is what I have been told: Both Phase converter companies told me that the saw will work with 240V, (with a phase converter), but it should NOT be run for extended periods of time, because over time it will overheat and burn up the motor. An electrician told me that most motors can easily take 10% more than the rated voltage and that the actual electricity coming into the box is rarely exactly 240 volts and varies from area to area. He told me to take a very accurate volt meter and measure the current at my breaker box, if the current is 230V or below, I should be fine (208 x 1.1 = 229 Volts). I have also been told that Rotary phase converters provide true 3 phase, and that Static phase converters provide a modified 3 phase and don’t provide the full voltage. I know that rotary phase converters are better than static converters, but given my particular situation, wouldn’t it be BETTER to use a static converter if it will provide slightly lower voltage? I just want to know if there is any way to get this saw to work on single phase 240 volt electric. I am not a contractor and would only be using this saw for my weekend projects, so it will have limited use. Any advice offered would be GREATLY appreciated. Thanks!
JimmyDee	quote: I have also been told that Rotary phase converters provide true 3 phase, and that Static phase converters provide a modified 3 phase and don’t provide the full voltage. I know that rotary phase converters are better than static converters, but given my particular situation, wouldn’t it be BETTER to use a static converter if it will provide slightly lower voltage? The static converter doesn't have quite the starting torque as the rotary converter. You should be OK in all areas of the voltages and starting torque. Sounds like the price was right for you on this saw. Jim
wareagle	Check the Mfg for variable speed drives. The small ones are fairly cheap and will convert single phase to three phase.
nfsus	Keep in mind that when using the roto phase or the electronic version you will max out the converter on start up if you dont size it large enough
lctrc789	See how much phase converter cost and then see if the saw was worth the savings in this case, I don't think they are real cheap but never the less it should work if you get the right size converter..... Good luck
Gauge	Wareagle, I have never heard of a Variable Speed Drive, and I am unfamiliar as to how it works. I imagine it allows you to adjust the voltage while also acting as a Phase Converter. Sounds interesting. As this will most likely be the only 3 phase piece of equipment in my garage, I think I will opt for the static converter (as opposed to the Rotary one). I have seen static converters rated for 1 to 3 HP on Ebay for under $100. I think the saw is definately worth the $100 investment (assuming it will work, of course) and I am not worried about a loss of power, as even if I get only 2HP, it will still be much more powerful than the 110V saws I have used with 3/4 HP. I REALLY appreciate everyone's responses. Thanks!!
Ryan_J	I agree with Pat 100%. Phase convertors are not something you just run across the street and buy with some spare change.
zapped208	Gauge, Just find and buy a single phase motor for this saw, and save yourself all the grief of trying to buy roto phases, and inverters and all that other B.S. Also that's why it's free......... no one can use it, cuz of the 3 phase. BTW, old is this saw?