OT - Electric motors single / 3 phase
Turbo Mini Forums

No you can do it. Take the cover off where the feed wire goes in and the terminals that you connect the Brown and blue to. If you then liook behind that there should be wires coming off that to the stator. this is where you switch 2 wires round. If I remember right there should be 4 wires in there. Just have a look at an industrial single phase motor.. Let me know how you get on.

ok I'll take a look, I've not collected the lift yet, so it will be a while

Team Racing

my dad looked into this as he has 3 phase machinery... mill/lathe etc...

he uses a inverter running the 2hp motor on the back of the lathe without problems and its not even turned up to full whack. Get an inverter which will do the job tbh its far simpler.

I've seen the future and tbh its Pie

yeah but its a lot cheaper to switch 2 wires round

I like a combination of the above - using two 1ph 1.5hp motors (not too expensive to purchase) connected up together, and making a switchgear panel to reverse the motors as Colas is sugesting...

The idea of using a truck starter motor is good - except every starter-motor I've found rotates the same way no matter what the polarity (think about peeps doing neg-pos earth conversions).

Jim - My dad knows about this kinda stuff - I'll email him this link and see what he thinks

Edited by turbodave16v on 5th May, 2005.

I had exactley the same problem, Jim. My solution was to get a single phase motor that drives a hydraulic pump which in turn powered a hydraulic motor via a 3/2 valve which would allow the hyraulic motors rotation to be reversed, easy eh??!! I also added a pressure relief valve into the circuit so that when the ramp reached the top of its stroke or if the motor was stopped it would dump the line pressure back to tank. The whole system cost me about 300 and is alot more reliable than an inverter.

As promised - a response from my father (who seems to know about this stuff)!

1. Single phase AC motors of more than fractional HP are difficult to acquire cheaply.
2. Single phase AC motors are very much more bulky than the same HP rating three phase motor.
3. To reverse a 3 ph motor it is necessary to reverse the connections between any two of the three phase inputs.
4. Reversing a single ph motor depends on the type.
a. Universal motors ( same as series wound dc motor ), commonly used for fractional HP applications such as sewing machines, vacume cleaners, electric drills etc. To reverse these motors it is necessary to reverse EITHER the armature OR the field winding; sometimes difficult as these motors are often sealed for life.
b. Capacitor start motors. Reverse main winding.
c. Split phase motors. Reverse either main or stator winding.
d. Repulsion ( 2 stator winding ) motors. Reverse connections to either stator.

Without doubt the most elegant and modern solution, if three phase is not available, is to use a modern three phase invertor designed for continuous rating at 1.5 times (minimum) the required HP . If £400 is the price then pay it to save messing about.

DC lorry starters and batteries sounds HEATH ROBINSON .You still have to make a safe shaft connection!!

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More thoughts - three phases are used in residential areas, the single phases are split equally amongst households. If you live on a really small avenue, it could be that only one phase leg is supplied there, but generally all three phases will run along the roads from the local transformer.

If lucky, and the phases are available at the end of your drive, it'll cost less than the price of a big invertor to get all three onto your property. It's always worth asking...

Edited by turbodave16v on 16th May, 2005.

there use to be 3 phase at the bottom of my neighbours garden, I still have not sent the form back yet to get a quote on the 3 phase install, I'll get this done asap

Team Racing

I picked a phase converter last night, it is made by transwave, the maximum output is 3.7kw, does anyone know what kind of hp motors this could run. The guy I bough tit from say he was using it on a 3.5ton four post vehicle lift, what had two 3hp motors. I would have thought that 2x3hp would have required more than 3.7kw, does any one know how to work it out?

Team Racing

Go here

http://www.mhi-inc.com/Converter/watt_calculator.htm

There is a calculator near the bottom. It should be almost 5 HP.

great thanks for that

Team Racing

at a push it probably would drive two 3hp motors.

I'll make sure I get a small lift, also most lifts are 3.5 ton, I only want to lift 650kgs, so I don't think it will be a problem (I hope)

Team Racing