Compressor motor questions !

[chopper746]

Hi guys,

New to the forum and need some advice. I have a 100ltr 3 phase compressor and have been looking online at converting it to single phase as that is what i require. I have looked online at some of the ways to convert it and would prefer to change the whole motor and pressure switch.My question is can i put a larger motor on it would this help in any way i.e run time reliability etc as they are only a few pounds different in price. The current motor is 1.8kw 2800w and looking online a 4hp converts to 2.9kw would this overrun the compressor ?

https://www.machinemart.co.uk/p/clarke-4hp-single-phase-2-pole-motor/

Any help would be great thanks

 

[rtbcomp]

1.8 kw can easily be supplied with a single phase motor, make sure the rpm is the same as the 3-phase. You could put a larger motor on, but the pump might not like it. The same rpm and the same pulleys won't give any more CFM, but it could run to a higher pressure, but then you have to be sure not to exceed the safe working pressure of the tank.

With a more powerful motor you could fit a larger pulley on the motor to increase the cfm, but that could over-speed the pump and you could actually end up getting less air.

Power = speed x torque, which translates to Power = cfm x pressure

You shouldn't need to change the switch, just use two of the poles, one for live and another for neutral.

 

[chopper746]

ok thanks they do have a 2.2kw option rather than a 2.9kw 4hp would you recommend that instead?

 

[the snooper]

ok thanks they do have a 2.2kw option rather than a 2.9kw 4hp would you recommend that instead?

what CFM is the compressor ?

 

[chopper746]

i have looked all over the motor and also the tank and it doesnt state it. current info i have is tank 100 ltr 11 bar max pressure, motor is 3phase 90s 400v 50hz 2800rpm 4-6.3amp 1.5kw hope that maybe of some use model is taskmaster 100 e2-hp compressor

 

[the snooper]

i have looked all over the motor and also the tank and it doesnt state it. current info i have is tank 100 ltr 11 bar max pressure, motor is 3phase 90s 400v 50hz 2800rpm 4-6.3amp 1.5kw hope that maybe of some use model is taskmaster 100 e2-hp compressor

a 2.2 kw will be fine then they are 3 hp and will run a 14cfm pump

 

[chopper746]

Ok thanks for your help i will get one sorted !

 

[rtbcomp]

There's no point in getting a more powerful motor than you need.

... 1.5kw hope that maybe of some use model is taskmaster 100 e2-hp compressor

1.5Kw/2hp would be about 9 cfm

 

[rtbcomp]

PS the 3 hp may have a larger shaft diameter so you'll need a new pulley as well.

 

[dannyp]

if going from 3ph to 1ph it helps to have a slightly bigger motor i think ( i know some will disagree ) but 3 ph motors work better imo . the inportant thing is to match the speeds

 

[brightspark]

3hp is 3 hp 3 phase or single . 3 phase have a better starting torque

 

[dannyp]

i'd like ro see a graph of max torque v's rpm for singel phase and 3 phase motors it chould be usefull

i think pritty much all the chinnese 1ph motors with the start cap have an issue, that point where the start cap is disconnected but before there upto full speed had them get stuck there before cyceling till the smoke came out but 3ph motor straight upto speed and run steady

 

[daleyd]

Another option,if your existing motor can accept 230v 3 phase, would be to fit an inverter, probably similar price to fitting a new motor (maybe cheaper?) and no messing around with mounting/shaft sizes/pulleys etc.