stevebubs
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| posted on 2/8/25 at 10:02 PM |
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Converting a lift to run on single phase
Hi folks,
Was lucky enough to have been gifted a Hofman GT2500 ramp a few years ago.
Finally at the place I can do something with it but don't have three phase, nor is it viable to get three phase installed.
Any ideas on best way forward to getting it working? New single phase motor, or inverter? Have a 40A feed into the garage and 32A circuit I can
connect it to.
 
Description
 
Description
[Edited on 2/8/25 by stevebubs]
Sylva Fury
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shindha
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| posted on 3/8/25 at 07:26 AM |
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Look at 3 phase VFD's google is your friend
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stevebubs
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| posted on 3/8/25 at 01:03 PM |
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Seems a minefield...
Any suggestions based on the motorplate above?
415v / 10A / 3KW
Sylva Fury
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J666AYP
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| posted on 3/8/25 at 11:55 PM |
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I would go for a VFD over a phase converter or motor swap.
VFD's are quieter, smaller and more refined than a phase converter and likely cheaper than a replacement motor.
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Theshed
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| posted on 4/8/25 at 12:55 PM |
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If the ramp is a screw lift rather than hydraulic it is very very difficult to get it to work with a VDF. I have been there. The VDY will tend to
stall out. You may have more luck with a rotary convertor. There is quite a lot on the interweb about this.
A motor change will work if you can get one to fit.
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coyoteboy
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| posted on 4/8/25 at 04:27 PM |
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I've no idea why you wouldn't just swap the motor, they're cheap and easy to use, unless an electrician can think of a reason why not
(I know it'll have a hell of a startup current but you can fit a slow breaker).
[Edited on 4/8/2025 by coyoteboy]
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stevebubs
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| posted on 4/8/25 at 10:13 PM |
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Leaning that way.. Have both 32A and 16A circuits I can plug it into.
Sylva Fury
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Schrodinger
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| posted on 5/8/25 at 07:21 AM |
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I may be way off target here but IIRC 3 phase motors can turn in both directions, however, single phase motors only turn one way.
So you may need to check how it goes up and down.
Keith
Aviemore
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coyoteboy
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| posted on 5/8/25 at 08:35 AM |
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Well sort of, single phase motors are reversed by a different method to 3 phase. You have to understand how to wire and switch both though, so fair
shout.
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mark chandler
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| posted on 5/8/25 at 04:10 PM |
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VFD with soft start is not going to work with a screw lift as it needs a huge amount of torque to get going, unless it’s a big rotary convertor I
expect you will fail so go single phase.
Make the single phase motor at least twice as powerful as the 3 phase rated one or it will struggle to start as they use a capacitor to get them going
and keep running - they do not have the torque.
You reverse a couple wires to spin a single phase the other way, you can use a switch or rewrite the relays that isolate the three phase motor, it’s
just a bit of head scratching but not hard - draw out the wiring.
My old German hoist has been great, I made the mistake of matching HP on the single phase, I also tried using capacities to run the three phase motor+
an old slave motor - both failed miserably so ended up buying the big single phase motor having wasted time and money!
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stevebubs
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| posted on 5/8/25 at 05:25 PM |
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Ok.... Cheers for the responses so far..
Torque is king.. Gotcha..
For single phase..
I believe 4 pole is better than 2?
What about Cap Start vs Cap Run
Sylva Fury
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stevebubs
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| posted on 5/8/25 at 05:26 PM |
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quote:
Originally posted by mark chandler
VFD with soft start is not going to work with a screw lift as it needs a huge amount of torque to get going, unless it’s a big rotary convertor I
expect you will fail so go single phase.
Make the single phase motor at least twice as powerful as the 3 phase rated one or it will struggle to start as they use a capacitor to get them going
and keep running - they do not have the torque.
You reverse a couple wires to spin a single phase the other way, you can use a switch or rewrite the relays that isolate the three phase motor, it’s
just a bit of head scratching but not hard - draw out the wiring.
My old German hoist has been great, I made the mistake of matching HP on the single phase, I also tried using capacities to run the three phase motor+
an old slave motor - both failed miserably so ended up buying the big single phase motor having wasted time and money!
May I ask what motor you ended up with?
Sylva Fury
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mark chandler
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| posted on 7/8/25 at 10:30 PM |
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3 x the HP of the 3 phase, capacitor start and run .
In 12 years I have had to replace the capacitors a couple of times, before use squirt EP90 directly onto the screws.
It will lift 2.5 ton’s off the ground so the motor can spin up before taking full weight, with this amount of weight you have to go straight to full
height as it will not spin up fast enough to gain more height, it will come down okay.
It’s a 2.5 ton Zippo screw lift with new screws.
Normal cars under 2 tons it works from any height.
Not sure if two or four pole, it’s the slower speed one to better match the three phase that came off.
The build quality of the zippo is very good, wide feet to spread the load with very robust arms so it does not droop like new ones, the feet extend
nearly as far as the arms reach so can be bolted to a household garage floor. Newer ones require a very robust concrete base as they only extend a few
inches past the vertical columns.
HTH
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stevebubs
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| posted on 8/8/25 at 08:43 PM |
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Cheers, Mark...sounds like they're similar vintage...the Hofmann is 1986 with a decent H Frame, also
Do you know the specs of your motor (I know you say "3x" etc but be useful to know if I'm looking in the same ballpark)
[Edited on 8/8/25 by stevebubs]
Sylva Fury
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fazerruss
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| posted on 8/8/25 at 09:21 PM |
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I converted my Werther screw lift to single phase and it works perfectly. My lift had been outside so I scrapped all the contactors and bought new. My
lift will pick up a 2.7 ton L200 from any height which isn't bad considering the lift is only rated at 2.5 ton!
I went big with the motor and fitted a 5 hp 1425 rpm motor. It has plenty of starting torque to deal with the problems mentioned. I also wired up all
the limit switches and skew detection switch so it works as it should on the button.
There was a fair amount of work involved but its served me well for the last 15 years
"if assholes could fly this place would be an airport"
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