kpsjoiner
Established Member
hi, i have the chance of a sedgwick spindle moulder sm3, but its 3 phase, could i buy a new motor and convert it to single phase? is it easy/possible? i have no idea with things like this.. thanks kevyn
kpsjoiner":24jqfqy9 said:hi, i have the chance of a sedgwick spindle moulder sm3, but its 3 phase, could i buy a new motor and convert it to single phase? is it easy/possible? i have no idea with things like this.. thanks kevyn
tisdai":2rlj2m3c said:My previous table saw was a 3 phase machine and when connected to the normal 240 volt socket it would only turn a couple of times and then stop. I ended up having a dedicated breaker installed in the consumer unit just for that, not sure now what size breaker it was.
If i was you i would Follow the link in the footer of Bobs / 9fingers reply to you.
It has a wealth of information about what you are looking for.
Cheers
Dave
xy mosian":19xb8ps4 said:Bob, I am no expert, but I wonder if it was intentional to question motor power twice?
3rd. line down to the right, and 6th. line down to the right.
HTH
xy
tool613":2xkc6xnc said:bob
thats a great flow chart. you know how us woodworkers need to visualizes. the vfd 3 phase combo is just the best thing sense the mechanical drive . i have in some cases taken out single phase motor for a vfd 3 phase combo speed control and or breaking. for a drill press i did it and it is great. i never change the belts. the vfd has almost replaced the mechanical drive. i got 4 vfd in the shop and am ordering another. really the best thing in years,and every one knows real tools are 3 phase
jack
tool613":337db8ls said:bob are you there resident go to guy. for phase conversion and motor controls, was that you that did up the pdf?
you can input single phase into most 3 phase vfds by derating the unit by 1/3 to 1/2. single phase input to 3 phase vfd is done all the time and more and more manufacture are providing the derated value with single phase input. a rule of thumb is 2/3 power out for a three phase vfd feed with single phase. so a 10Hp vfd three phase in feed with single will give you power to run about a 7.5hp motor. what i have found is that a vfd up to 3hp is cost effective for phase conversion. as the price goes why up after that. but most vfds can be feed single phase power.
if your chart is to reflect what to do for phase conversion than i think it is great. you could add that larger units are available but the cost goes way up after 3hp
jack
9fingers":2sn3rtsi said:tool613":2sn3rtsi said:bob are you there resident go to guy. for phase conversion and motor controls, was that you that did up the pdf?
you can input single phase into most 3 phase vfds by derating the unit by 1/3 to 1/2. single phase input to 3 phase vfd is done all the time and more and more manufacture are providing the derated value with single phase input. a rule of thumb is 2/3 power out for a three phase vfd feed with single phase. so a 10Hp vfd three phase in feed with single will give you power to run about a 7.5hp motor. what i have found is that a vfd up to 3hp is cost effective for phase conversion. as the price goes why up after that. but most vfds can be feed single phase power.
if your chart is to reflect what to do for phase conversion than i think it is great. you could add that larger units are available but the cost goes way up after 3hp
jack
Well sort of :wink: The pdf is all my fault!
I take your point about feeding single phase into a three phase inverter with suitable de-rating but that does not work for UK supply voltages
We have 240 single phase and 415 three phase supplies so three phase UK inverters expect 415v input an flag under voltage errors if 240v single phase is connected. Now it is possible to use an transformer (isolating or auto) to step the 240v up to 415v, feed a three phase input inverter (suitably de-rated) but that is getting quite expensive unless you have the transformers already.
If the inverters are opened up and extra rectifiers and reservoir capacitors added, it is possible to do away with de-rating and that should work for Canadian supplies too. All that is needed is sufficient current handling from the rectifiers and sufficient reservoir capacitance to keep the DC ripple within required limits. Quite dangerous voltage levels when playing with these so care and knowledge required.
Not sure about Canadian power distribution. How do you guys get enough volts to power your 3 phase inverters?
Cheers
Bob
ps Note to self: Must add comment to the next edition of my motor write up to stress application to EU based power systems only.
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