OK a bit off topic , but worth a try.
A good friend is trying to start a small garage service going to service and restore old cars.
He picked up a 2500 Kg two poster car lift from the adds and installed it. At the same time the Electric supply company was approached and survey and price sought to supply 3 phase to the garage to deal with the various things he would need.
The price that came back to him was over £9,000 plus VAT. Now whilst that may not seem a lot to some people, it is a bloody great deal when starting and needs a lot of through put before that sort of price can be justified. It seems there is a general problem in the area, of the transformer being under rated for the surrounding houses and farms and the price included part charge for new transformer of larger capacity!
So I though I would let him use my static converter 240 in 415 out at up to
4 HPIt crippled the mains when we tried to start up the 4 HP motor on the ramp even without a car in place.
The mains input dropped to around 180 Volts to the static inverter. Larger cable is going to be fitted to help minimise the volts drop taken from the household supply, but the fears are that even this will not solve the issue.
I have been thinking of reducing the ramp motor from 4 HP at three phase to
2 HP and going to Single phase supply, The start-up currents would be reduced and hopefully less chance of taking the supply down.Now as it stands the 4 HP motor is 3 phase, runs at 1415 rpm uses pulleys to reduce speed 70 cm and 230 cm so around 1/3 reduction in speed and the lift screws are 5 TPI.
So my basic working out gives me 1415 * 70/230 = 430 rpm screw speed
430 rpm / 5 TPI = 86 Inch lift a minute or around 7 foot lift in a minute which I guess is about right.Now going down to a 2 HP motor would I need to need to reduce the lift speed by 2 by changing the motor reduction by 6 to 1 instead of the 3 to 1 now in use. Assuming same rpm motor.
Or would I in fact have to go even higher in reduction due to using a single phase motor that has lower starting torque then a 3 phase 2 HP motor.
say to 7:1 reduction from the 3:1 reduction now in use.
Any advice from those in the know is very much appreciated especially from anyone else that has done a similar change.
-- Cheers Adrian.