ianjenn
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| posted on 12/10/12 at 08:17 PM |
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car lift convert 3phase to single phase
I have just bought a single post car lift to go in my recently extended garage. It currently has a 3phase motor fitted which I intend to swap to an
equivalent powered single phase motor. The question is will I be able to use any of the other components in the control box such as on/off switch, up
and down switch and limit switches. I am not sure what the other bits are in the picture or whether I can use them. One looks like a transformer? Any
advice.
larger link to control box
[Edited on 12/10/12 by ianjenn]
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SteveWalker
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| posted on 12/10/12 at 08:40 PM |
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The link doesn't work.
Most of it will probably be alright, but you will need some changes.
3-phase motors are reversed by swapping two of the phases over.
Not all single phase motors are reversible. You need one where there are four wires rather than two brought out to the connection box (the two pairs
may be connected on a pair of common terminals or by two links between each pair of terminals) and you'll have to arrange for the two pairs to
be supplied separately and for one pair only to be swapped over for reversing.
Don't forget that you may have an MCB or fuses and a contactor with a motor overload trip, all of which may need replacing (the overload may be
adjustable).
If you re-use a three phase mcb or overload unit for a single phase motor, one of the phases needs to be looped from the output side of the mcb or
contactor back into the spare input before going to the motor (so that all three phases of the mcb or overload unit are used).
If you can get a working link for the photo, I'll take another look.
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SteveWalker
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| posted on 12/10/12 at 08:41 PM |
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Your small photo is now working, but the link to the larger one still isn't.
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daviep
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| posted on 12/10/12 at 08:49 PM |
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Working LINK
Simplest solution would be to use a single to three phase inverter, see HERE
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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ianjenn
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| posted on 12/10/12 at 10:28 PM |
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Thanks for posting a link to the photo. I thought I was better off getting a new motor. I didn't think an inverter would work out any cheaper
and probably more expensive. The existing 3 phase motor can take a 240v or 415v 3 phase input. 240 to 415v 3 phase inverters seem really expensive and
I didn't think a 240 to 240v 3 phase would have the same power. But I don't really know what I'm taking about so any help greatly
appreciated. A cap start/cap run single phase reversible motor with flange mount is about £200. But If I have to start buying new drum switches etc it
might mean an inverter is the best option.
Could you have a look at the link Steve and see if you can point me in the right direction for reusing any of the existing components. many thanks
https://picasaweb.google.com/lh/photo/Uzm-bQi3XEfcUjqyM6IJLtMTjNZETYmyPJy0liipFm0?feat=directlink
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SteveWalker
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| posted on 12/10/12 at 11:16 PM |
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I can't tell properly from the photo, but I've taken a guess at it. However I've not included the limit switches - I assume that
these are wired to stop movement at the limits of travel, but there must also be some way of still running the motor in reverse.
The sketch is very rough, but gives you an idea of how your components may be being used.
Link to sketch
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Autosri
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| posted on 12/10/12 at 11:23 PM |
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you can run a three phase motor on single phase by using a capacitor or a pair of capacitors you can use one for cap start or a pair for cap start cap
run do some googling and you should find what your after
what voltage is the contactor coil if its 230 your okay if its 415 it wont work
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ianjenn
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| posted on 13/10/12 at 04:13 AM |
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Hi Steve,
I couldn't get your link to work to see the picture.
I have seen 3phase run using capacitors but it was my understanding the motor would run at 50% power because of not using one winding which is not
going to be good enough for a car lift
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fazerruss
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| posted on 13/10/12 at 09:06 AM |
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I did this exact conversion on my Werther two post lift. Best thing to do is remove all the switch gear from the box and start again. That way you
know everything is rated corectly. The existing three phase gear may not be up to the job because when you go down to 240v the current draw is
increased. I fitted new motor and all switch gear for about £250. All bit bought new off ebay.
"if assholes could fly this place would be an airport"
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Bigheppy
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| posted on 13/10/12 at 09:09 AM |
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Jusy get a single to three phase converter. Then leave all controls as they are no messing.
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AdrianH
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| posted on 13/10/12 at 09:09 AM |
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You can use that method (Cap Start) if you have an idle motor in there as well.
I Built my own for a Harrison milling machine. The motor on that is 2HP, so I built a 240 Volt 3phase using cap start and 3HP idle motor. The
Harrison motor was changed to 240 Volt delta rather then 415 Volts star and it works reasonably well.
I also have under the bench a 240 to 415 cap start unit static box if you wish to try and use it, but think you will still need to have an idle motor
in there before your control box would work.
What is the size of motor or motors on the lift?
Adrian
[Edited on 13-10-12 by AdrianH]
Why do I have to make the tools to finish the job? More time then money.
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ianjenn
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| posted on 13/10/12 at 10:11 AM |
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Ok. So the current motor is 3kw (approx 4hp) so if I get a >5hp 3phase motor and run that using 2windings and a couple of caps as an idle motor.
Then feed from this to my ramp its game on. I will also then have 3phase for any future equipment like milling machine.
There is plenty of info on the net about what capacitors to get.
[Edited on 13/10/12 by ianjenn]
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SteveWalker
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| posted on 13/10/12 at 08:05 PM |
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quote:
Originally posted by ianjenn
Hi Steve,
I couldn't get your link to work to see the picture.
I have seen 3phase run using capacitors but it was my understanding the motor would run at 50% power because of not using one winding which is not
going to be good enough for a car lift
Sorry about that. I haven't used Picasa before and have obviously ended up with the photo not being shared publicly.
U2U me your email address and I'll send it to you that way.
SteveW
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