A very informative video about the wiring of dual voltage motors which is usually a black hole to us mechanically minded. Thank you it has helped me, and I guess so many others in how it should be done.
Just as an addition for your viewers information I have covered the selection of capacitor size in my series of videos on this subject. "How to do it, run a 3 phase motor on single phase supply". It is important to use an AC capacitor of the right voltage and capacitance. A higher voltage is not a problem, but lower is. A DC cap will go pop when connected to AC. Always enjoy your videos, and the quality of some of your close-ups when machining is tremendous, Cheers, Andy.
+Andy Reynolds If I may ask. I have a 3 Phase induction Motor 3HP 2.2 KW with 240 in and 3 phase out , which at present is setup with a variable frequency drive. I would like to run just on 240V as I need the variable frequency drive for another machine. First is this possible, what are my losses? and what size cap would I need. Regards Peter
Peter I suggest you watch my 6 part series as this will answer most of your questions. With that size motor you will need a start cap as well as a run cap. The run cap should be about 50 Uf, but you will have to check the voltages whilst the motor is running. Cheers, Andy
Hi John i did the same with my coolant pump, and did a bit of research and found that 70uf per horsepower is about as near as it gets, thanks for the videos and keep them coming, all the best to you and your wife, regards clive
Concise, on topic and with functional example, that is how instructional videos need to be made. I went through 10 other videos before this that made everything completely and utterly unclear.
Thank you, great information . I was wondering how these type of motors should be connected, but now I know. because the windings are straight across from eachother, U1 opposite of U2 etc, it made no sense to me. I expected the windings to be like in a 400/690 motor, U1 opposite W2 etc
The rule for capacitors usually is 70µF per Kilowatt of output. If the value is too low, the motor won't start properly, if it is too high, there will be extensive heat buildup which is why some motors have a starting capacitor that is only activated for start-up and then disconnected. The running capacitor has a lower value and ensures the motor stays cool during run.
Here in the states we are always trying to run 220vac 3ph from 220vac 1ph. I built my own 5hp RPC and have the voltages pretty well balanced on each phase, and kept the amp draw at a low level. I will only be able to run one of my machines at a time, but then there is only one of me.
Did that with the pump on my harrison last week. Used a 4uf motor start capacitor, £2.50 on eBay. Runs well. Did it on my Boxford years ago and it has never given bother.
Tony Simons It should be a run capacitor, not a start capacitor. Start capacitors are only rated for a few seconds service (in motors with centrifugal switch) and will overheat if used as run capacitors.
This will work on a small, lightly loaded motor. However, you will lose torque, because the windings are in balanced. The capacitor does give it sufficient torque to start, but because it does not shift voltage by a full 120 degrees phase angle, that is why the voltages are unbalanced. This will create additional heating in the motor. If this were a heavily loaded motor, it would overheat and eventually burn out. I'm an electrical engineer, for the past 40 years, this is what I do for a living. There are small variable frequency drives that will allow a small motor to run on 3-phase power from a single phase source.
+Lorena Dervishi , no amount of Capacitance alone will create a third phase at 120 degrees. 90 degrees of angle is sufficient to allow starting of a rotating motor, but the current flow to the windings will remain unbalanced, causing heating of the motor. Keeping the capacitance in the circuit will result in a very significant leading power factor that will cause further heating of the windings. The only way to create true 3-phase power from a single phase source is either a motor driven synchronous generator, or an inverter. Multiple 3-phase motors running off a rotating phase converter will improve the balance between phases, but not entirely eliminate it.
Good sir I needed to ask, I have a 380v 3.0kw motor that I need to convert to single, what would be the size of capacitor ratings without Burning thing's out. Plus I have a theory. To create 3 phase power can take a single phase wire and connect via looping from one MCB to another whereby creating 3 outputs Of Power from one line which now gives me 3 phase power . Or am I wrong
Mr Moran, if I were to use a small three phase motor designed for 380v in delta configuration with a vfd that outputs 3 phase 220volt, do you think I'd have any issues. The motor is for a pool pump only .75hp.
i guess im asking the wrong place but does any of you know of a tool to get back into an Instagram account..? I stupidly forgot my login password. I would appreciate any help you can give me.
@Hayes Elisha i really appreciate your reply. I got to the site through google and Im in the hacking process now. Takes a while so I will get back to you later with my results.
Nice job explaining how to to rewire the motor. i remember when i put a vfd and had to rewire the motor to delta. i had no idea so i got a mate to do it.. looks simple after seeing this great job. hope debs doing well :)
An alternative for the small motors is to get a motor in the same frame size made by the same manufacturer that is the single phase variant and swap the stator sections. The rotor will typically be the same size and then it will be single phase. The leftovers you can put back together and have a 3 phase motor, which somebody else can use again. Works on those motors with special end bells or specially modified shafting, and can work quite well. At least with this conversion it will run cooler.
yes, but you have to source another identical motor, this way is low cost, no real hassle, and you can use caps from old flourescent light fittings. Cheers
Hi there john, I've been an avid watcher of your vids since I first bought a little 100 year old relmac lathe 18 months ago or so, I have learnt so much and really enjoying my hobby. This vid has made me need to get in touch! I have a 3 phase motor I was selling on ebay to get a single phase to run my other small hobby lathe,but after watching this I have found mine can be converted too,just one question, you say that by swapping the connections over will reverse the direction of the motor..... is there anything available that can be wired in,such as a switch that could reverse the motor when needed( threading small threads,for instance) and how would it be wired in? thanks for taking the time to make these vids, you have no idea how valuable they are to a 44 year old novice such as me! congrats on the channel and love to debs,my wife and I are still including her in our prayers( I give lynn an update everytime you give us an update!) best wishes. Dan,leicester UK
John if you look at the original links I bet there are will be two stuck together and appear a just one. Swopped plenty over as we used single phase inverter to save cost (they give out 220/240v 3phase) on industrial Carpet Backing plants.
Excellent video. But what size capacitor do we use on which motor power? Is there any formula for that or do we orientate only to the supply voltage? Any help would be appreciated.
There is an earth screw in that frame, partly hidden under the terminal block, the earth must go to that from the power cord. You can do additional earths, but the cord earth must go direct to the frame. That way if the motor shorts to earth and you pick it up you will still have the motor earthed, and will not get a shock.
Now try to fit that spaghetti inside the cover and close it, plus use a second cable gland for the capacitor. You should get a motor run cap with integrated lead, so that you have no exposed terminals outside. That way you just use a large P clip or a cable tie to hold it to the motor side.
SeanBZA Now that I have it running I will get a new "run cap"No exposed terminalsI ran a similar set up on my Boxford for 10 yearsThanks again for the heads up on the earth tag RegardsJohn
I somehow expected Mr. Bozo to go ZAP-POP-FIZZLE At least you have 3 phase. It would cost thousands to have it ran to here. So we are stuck with converters or VFD units. The nearest 3 phase is well over a mile away. Good video.
Big'un44 He doesnt, he uses a converter too, and thats wjhy he converted this to 240v to save always having to run his converter, passes Big'un44 some coffee to keep him awake for the video! :}
Hey john, im wanting to run coolant on my lathe. Ivw got the setup but ive always herd if your not going to use it everyday it will go "off" and start to smell. Unless theres better coolants now days?
It really helps me with my comprrssor the other thing i need to know can i change the speed of the motor with same delta connection my motor runs a little slow
Hi, Tried your method on a Lowara star /delta motor. I triple checked the wiring, started it and hummed, smoked and the shaft hardly revolved. Any ideas on what l may have done wrong? I used a 20uF capacitor. Cheers.
Hey, Is there a reason why you connected the Capacitor to the middle and right slot? does it matter where it's connected to? Can i connect one side of my capacitor to the left ring and the other side to the right ring and leave the center ring without a capacitor lead?
I am thinking of doing this to a 3/4 hp motor on a tool & cutter grinder. A capacitor is far cheaper than a converter or inverter.😕hmmm..... As it is under 1hp, will the motor still overheat? I also need the machine to be able to switch into reverse as well. Will the machine still switch into reverse via the forward and reverse switch with the capacitor fitted to the motor or would I be better of just investing in an inverter?....
John your electrical work looks about as bad as my machine work. ;-) The capacitor voltage will go down under load anyway. Finally we will have running water at the mill, nice!
ah looks like motor on my cazenueve lathe, now, I just scored two hydraulic power packs 2.2 kw wired in delta 220, I swing them to star, so i generate my 3phase from a Lincoln vantage 400 gives 17kw 440 V the controls are 24volt dc, came from a ship,so i will need swap solenoids to 230ac can you advise how powerful a 3ph motor will run as you've done hear on a cap start, you taught me something today , THANKS
good day how to find the right capacitor for any motor. i have air comprasor and its working on 3 phase and i need it to work on single phase. how to find the right capacitor size thanks for you
Hi John Just a bit of information I do not know if you are aware but there is a model engineer exhibition at Harrogate show ground this weekend Friday to Sunday. There are lots of lathes mills plus accessories plus of course lots of engineering models. For more information click onto National Model Engineering Exhibition Harrogate 2015. Regards Peter Tyneside Model Engineers
Hai my dear good video vison please let me know the caperciter how much uf we should used i am dias From srilanka bentota please reply me soonly thanks
