Converting car 3 phase switch to single phase

[jddevel]

I have been offered a two post car lift which currently operates of off a 3 phase supply. I have a brand new single phase 3hp motor which I believe will run the lift but I assume I will need to alter the current operating switch. Advice please. I realise I could buy an inverter and use the existing set-up but my existing single phase motor will just be wasted.

 

[plugwash]

A lot more details are going to be needed to fully answer this question, but two main ones spring to mind.

1. How much current does the new motor draw and can the existing switchgear deal with it. A 230V single phase motor is going to require more current than a 400V three phase motor to do the same work.
2. A car lift needs to go up and down. Is this handled mechanically or by reversing the motor? pretty much any three phase motor can be reversed by swapping two of the phases, on a single phase motor reversing typically means swapping the polarity of some but not all the windings.

 

[Harry Bloomfield]

2. A car lift needs to go up and down. Is this handled mechanically or by reversing the motor? pretty much any three phase motor can be reversed by swapping two of the phases, on a single phase motor reversing typically means swapping the polarity of some but not all the windings.

Some are hydraulic, so a matter of pumping oil in to go up, releasing it to go down.

 

[JohnW2]

Some are hydraulic, so a matter of pumping oil in to go up, releasing it to go down.

Indeed. In fact, even if it isn't hydraulic (although I think most of them I've seen have been), it would surely be unnecessary to have a motor 'bringing the lift down', when gravity is there to do it for one, at little or no energy cost?

Kind Regards, John

 

[ericmark]

The question is start load, both will it start under load, and what load it puts on the supply.

With the type that turn a screw it does need to reverse and power down, and hydraulic may need so de-loading valve for the motor to start.

It is common to have the de-loading valve connected to the star/delta starter, same applies with compressors. I am sure one could use timers to de-load, but it is not as simple as just swapping the motor.