compressor motor

[dandee1234]

Hi
I have been given a 3 phase compressor for home,looking at the wiring
on the motor is it possible to wire the motor to single phase for home
use UK 240 Volts
Many thanks dan

 

[jraef]

No, not really. You can find a myriad of ways to either “trick” the motor into starting, then running at a capacity of roughly 1/3 to 1/2 of what it is rated, or you can buy or make a “phase converter”, or you can buy a Variable Frequency Drive to use as a phase converter.

The first option can only work on a compressor if you can change the belt pulley ratio to provide higher torque at a lower speed, which results in the motor having to run a lot longer to achieve pressure in the tank and then take longer to recover, reducing the amount of air you can use.

The 2nd option is likely going to cost you more than replacing the motor with a single phase version. There are “static phase converters” that can also reduce the usable power available from the motor, or “rotary phase converters” that use another motor to get you 3 phase for this motor, which is pointless compared to just buying a single phase motor.

The VFD option, because your motor is only 2.2kW (I think, hard to read on my phone), is your least objectionable one for continuing to use that “free“ motor. You can easily find VFDs designed for single phase 230V input, 3 phase 230V output. You can also use some that were designed for 3 phase input, but you must at least double the size of the VFD compared to the motor, if not more., so a minimum of 5kW. Also, be wary of low cost used VFDs on auction sites because if they have been sitting unused for years, they need specific a treatment that you may not be capable of to avoid damage from just applying power to them (capacitor reforming). This too may however be more expensive than a used single phase motor.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[dandee1234]

Hi
Thanks for the great reply
i had it in my head that the 2 brass bridge pieces on the left of
the motor wiring could be bridged to the other side some how to
make it run 240v.must have dreamed it


i was thinking of a motor swap then
found this do you think it will run the

Link

Many Thanks

 

[itsmoked]

Yes that can replace the one you have IF it's shaft is the same height and diameter as the 3ph one. We can't tell with the information you've provided. There is a hole in the belt protection cover that the new motor shaft should fit thru. Also the sheave hole diameter need's to match or you'll have to solve that issue also.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Speed is important also.
I can't make out the speed of the three phase motor.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[dandee1234]

Hi all
Thanks for all the info
What gets me is the the motor tag says 230/400v ?
original motor on compressor speed 2845 rpm
can anyone enlighten me on the 230/400v
Many Thanks

 

[zeusfaber]

There's two legitimate ways you can fit the links in the terminal box, and they configure the motor windings in two different ways. If you look at the rating plate again, that box doesn't just just say 230/400 - it also contains a pair of symbols. What that's saying is that you can run the motor on a 230V (phase to phase) supply if you connect the windings in Delta formation, or on a 400V (phase to phase) supply if you connect them in Star.

From your very first photo, your motor is currently configured in Star - (for Delta, you'd see three links running left-right, rather than two running top-bottom like you've got)- which is as you'd expect if it had previously been run on a 3 phase LV supply in the UK.

In a way, you're right about being able to move the links to make it run on 240V - but it would have to be three-phase 240V measured phase to phase, and that's not a supply you will find a lot of and certainly not the one you had in mind.

A.

 

[che12345]

Dear Mr. dandee1234 (Mechanical)

Q. " What gets me is the motor tag says 230/400v ? "
A1. I noticed learned advice proposals posted by regular respected contributors are valid. These invariably involved (some external devices or replacing the existing [three-phase motor] by a [single-phase]).
I am proposing for your consideration, to make an inquiry to your local utility the "estimated cost" involved to replace the existing [single-phase] source by a [three-phase] supply. It depends on the availability of the nearest three-phase source. It may not? be far too expensive.
With a three-phase supply:
a) your problem is solved without having to add any external devices or replacing the existing motor, with the exception of a very minor installation of a three-phase socket outlet to the motor.
b) consider that your existing [three-phase] motor is far more reliable than a [single-phase] motor or any other external added devices,
c) it would be beneficial for long-term expansions, without having any additional cost involved to run any existing single-phase loads and any additional three-phase loads in the future.
A2. The supply in UK is 400/230V 50Hz i.e. 400V three-phase and 230V single-phase. Your existing motor is perfect fit for the supply in UK.
Che Kuan Yau (Singapore)

 

[dandee1234]

Thank you guys
the information has been invaluable and cleared alot a things up for me

as i only have this compressor as 3 phase,a motor swop is the way i will

look into this.compressor will only be used now and again

(moving the bridges around to pick up 240v of a 440v supply makes sense now )

Many thanks to all who gave info

cheers and stay safe

dandee