3 phase hydrovane to single phase?

[stef1]

Hi all,

As some will know I am looking for a hydrovane compressor - not having much luck right enough.

I have had a thought, buying a 3 phase unit and convert it to single phase by changing the motor.
Now I am an electrical fitter to trade so I know what i'm doing to some extent but I have never done a conversion before on anything.

Anyone got any experience of this? problem I guess is without the compressor I wont know the output shaft size of the motor and a few other details.

plenty of good looking 3 phase units out there, a few that would be ideal if this is possible.

 

[madkayaker]

would be a case of finding a single phase motor same foot and motor size. a decent motor supply spot will be able to advise. the information is on the motor data plate

 

[stef1]

I will see if the seller can give me a picture of the motor plate. cheers

 

[brightspark]

u would be limited to about 5hp on single phase so that should narrow your choice and size down

 

[stef1]

5hp would be more than enough, 3 or 4hp is where im looking to be.

 

[stef1]

Is my biggest problem here the size of the motor shaft? I see that some (single phase) 3hp motors have 24x50mm shaft where as the 4hp have 28x60mm

I have no idea what the dimensions will be of the 4hp 3 phase motor fitted to the compressor, im trying to google that now and see if there is a standard.

Just realised that one compressor I had in mind is a 4kw, so 5.5hp. I can get a 5hp single phase 1400rpm motor but its not exactly cheap!

 

[dannyp]

bigest probelm is quality of the motiors really

a 5hp singel phase motor will struggel replaceing a 4hp 3 phase on a compressor

3 phase motors hae some serous starting torque and wind up really well, singel phase motors struggel, espectaly the chinesse crap.

problem is they use a massive start capacitor with a centrifugal switch if there is much inertia this switch gets a huge hammering and will fail but with compressors you get an extra kick in the teeth.

the centrifugal starter has to drop out before motor reaches full speed else it would nevevr drop out and theh motor would fry. when it drops out teh max torque drops but the compressor is starting to pump air at this point and the motor is still tryng to accselorate. it'll tend to dye back down and hit the start capcaitor again untill it burns.

i ended up puttign a contactor in to take the load of the centrifugal switch, and then useing a timer and had to hold the contacor in for 5 seconds after the centrifugal switch gave up to make sure it was all up to speed. motor quit quite quickly as well

 

[Mr shiney]

Just stick a 3 phase convertor on it. I got a 5.5hp unit from Clarke from Machine Mart for about £300. You can then run other 3 phase stuff as well. I have the PC60 unit which is totally portable.

3 phase motors get the power from the additional phases not from a bigger motor.

 

[stef1]

Cheers guys,

Yeah I had considered one of those units actually. It might be the way to go, it will be about the same cost as swapping out the motor and things anyway.

I will have a look at the unit you have mentioned when I get home from work tonight.

 

[brightspark]

Just stick a 3 phase convertor on it. I got a 5.5hp unit from Clarke from Machine Mart for about £300. You can then run other 3 phase stuff as well. I have the PC60 unit which is totally portable.

3 phase motors get the power from the additional phases not from a bigger motor.

realy u need a rotary converter not a static for a compressor .static do not put out full power on all 3 phases and there not much use on 4 poster lifts either

 

[stef1]

this is looking like I better stick with a single phase unit to keep it simple to be honest although the pc 60 does look like a good bit of kit.

Im stuck between a rock and a hard place here!

I was hoping to run my compressor from a 16a commando socket, If I go 3 phase and use a pc 40 with a 3hp compressor I will probably just get away with this.

 

[stef1]

Well I have an answer to this now, just bought a hydrovane 15 with 3hp motor.

It looks very clean for being potentially 19 years old