Discuss Single Phase 230V supply and 3ph Compressor install. in the Commercial Electrical Advice area at ElectriciansForums.net

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Hi guys,
Have an option of an old, but really solid superb condition and well made large +/- 200ltr compressor from Denmark. Rarely used since purchased/Build 1987.
Only supply I have is 230V Sing/Ph. Never had any dealings with 3 Ph.

First name plate.
Grundfos 3~MOT MG90LAR-24F115 No: 870000??
220 Δ/380 Y V 50hz 2855 /min
9.0 / 6.2 A IP 54 CL. F 2.2Kw
Cos 0.9 P1 - 3.0 Kw

Over a day searching and it appears there is no history on this now. Called people that were of no help on the plate details surprisingly. Suspect 220 delta 9.0A and P1-3.0 Kw relate to start up? Seeking confirmation and would be appreciated.

4mm2 supply +/-50M (pity not 6mm2) from main Cons box 32A MCB to 2nd Con Box with choice MCB and RCD. No other load.
At present to install this 3Ph with the 1Ph 230v I can only see a VFD as the option. If there are other options would be pleased to know. There are always unknown factors and losses with projects like this and hoping to hear those views of concern.
Compressor would be 3-4m from the Cons box and controller, if a safe and sensible solution ticks the boxes if and when it will be used, which will be little, not daily.
Thanks in advance.
 
might be cheaper to change motor to single phase unit.
 
think i paid around £100 for a 3 HP motor in a similar compressor.the original motor burnt out. the idiot who borrowed it ran it off a long extension lead and failed to see the motor had stalled due to volt drop. hence a dead motor.
 
think i paid around £100 for a 3 HP motor in a similar compressor.the original motor burnt out. the idiot who borrowed it ran it off a long extension lead and failed to see the motor had stalled due to volt drop. hence a dead motor.
This is a known issue to me, hence why I carefully explained without wanting to pretend I'm expert about cabling. This motor I saw a replacement online 3~ available £1,246 .... that is some dough:oops:.
Can see the build quality is very good, as most engineering was.
Best stick with it and find another way round it.?
 
You get a motor a lot cheaper than that. Madly enough I’ve found a few at car boot sales over the years but keep an eye on the usual suspects such as eBay and Facebook marketplace.
 
220/380 is not standard UK three phase so you won't be able to use an off the shelf phase converter.

I suspect you will need to go for a VFD to run this motor.
Thanks for the reply.
The compressor is in Spain and setup on 3~ which the owner had upgraded his place in the past. It originated in Denmark, although he was German. Since passed away.

Based on limited knowledge of VFD, it seems the correct rating is quite important to match, which may be different from the 2.2Kw on the motor. Perhaps contacting one of the suppliers will help?
 
Thanks for the reply.
The compressor is in Spain and setup on 3~ which the owner had upgraded his place in the past. It originated in Denmark, although he was German. Since passed away.

Based on limited knowledge of VFD, it seems the correct rating is quite important to match, which may be different from the 2.2Kw on the motor. Perhaps contacting one of the suppliers will help?

The 220V 9A Delta from the nameplate is consistent with a 2.2kW motor. When running with a VFD it has to be at least equal in rating, and not too hugely over as VFDs are not designed to reliably protect motors much smaller than their rating from overcurrent.
If I had this compressor in front of me, I'd be perfectly happy to hook a 2.2kW drive up to the motor and press the go button.
 
The 220V 9A Delta from the nameplate is consistent with a 2.2kW motor. When running with a VFD it has to be at least equal in rating, and not too hugely over as VFDs are not designed to reliably protect motors much smaller than their rating from overcurrent.
If I had this compressor in front of me, I'd be perfectly happy to hook a 2.2kW drive up to the motor and press the go button.
Thanks for the reply.
I'd be happy to find a 2nd hand Rotary converter or VFD, but all about timing that appears.
It does look like a VFD is 6/4 Fav though. They are expensive, and must decide. I have looked at a few, avoiding e-bay and Amazon, just blatantly gear from China. Was tempted all but 30seconds. Invertek make them, I have an one on pool system, good gear but pricey.
Is there a make you might be able to suggest or know of that is decent. This compressor wont be used much.
Thanks again?
 
I'd have thought that it woukd run fine in delta. L & N to two terminals, cap between one of those and the other corner to assist the third phase. That is the basis of a rotary converter.
You'll probably want extra cap during start.

Having played with making a rotary converter in the past, look forward to a few blown fuses/tripped breaker while you work out the amount of cap needed.

It will help a lot if the compressor can be unloaded during start.
 
Thanks for the reply.
I'd be happy to find a 2nd hand Rotary converter or VFD, but all about timing that appears.
It does look like a VFD is 6/4 Fav though. They are expensive, and must decide. I have looked at a few, avoiding e-bay and Amazon, just blatantly gear from China. Was tempted all but 30seconds. Invertek make them, I have an one on pool system, good gear but pricey.
Is there a make you might be able to suggest or know of that is decent. This compressor wont be used much.
Thanks again?

I'd have thought that it woukd run fine in delta. L & N to two terminals, cap between one of those and the other corner to assist the third phase. That is the basis of a rotary converter. You'll probably want extra cap during start. Having played with making a rotary converter in the past, look forward to a few blown fuses/tripped breaker while you work out the amount of cap needed. It will help a lot if the compressor can be unloaded during start.

Using caps to make a pseudo-three phase supply is always a bodge. True single phase motors have their run winding designed to carry the full power of the motor, three phase motors are intended to carry a balanced load across the three windings.

I would also not use a cheap rotary converter, as these supply three lines at 0/90/180 not 0/120/240 phase angle so you still need to de-rate your motor. A compressor is exactly the wrong load for any kind of kludged up pretend three phase supply.

Use the right tool for the job, in this case that is a true 400V supply or rewire the motor to delta and use a 230V 1-to-3 phase VSD. Otherwise your next thread will be entitled "I blew up my compressor motor" :)
 
Using caps to make a pseudo-three phase supply is always a bodge. True single phase motors have their run winding designed to carry the full power of the motor, three phase motors are intended to carry a balanced load across the three windings.

I would also not use a cheap rotary converter, as these supply three lines at 0/90/180 not 0/120/240 phase angle so you still need to de-rate your motor. A compressor is exactly the wrong load for any kind of kludged up pretend three phase supply.

Use the right tool for the job, in this case that is a true 400V supply or rewire the motor to delta and use a 230V 1-to-3 phase VSD. Otherwise your next thread will be entitled "I blew up my compressor motor" :)
Thanks for the reply.
Yes Sir, I have seen a capacitor setup, but it was as an experiment and deemed not a good method.
Not clear on your last reply after your first an earlier one you confirmed you would be happy on this setup to go with a VFD.
Have you has second thought, or have I missed something there?
I had accepted using an Invertek, would be over £2-250. If this is not the tool for the job, I definitely would not spend that.
 
Use the right tool for the job, in this case that is a true 400V supply or rewire the motor to delta and use a 230V 1-to-3 phase VSD. Otherwise your next thread will be entitled "I blew up my compressor motor" :)

FVD & FSD are the same thing, variable frequency drive or variable speed drive.
that is the route i would be going down, wire the motor in delta and use a VSD.
 
Use the right tool for the job, in this case that is a true 400V supply or rewire the motor to delta and use a 230V 1-to-3 phase VSD. Otherwise your next thread will be entitled "I blew up my compressor motor" :)

A true 400V supply would be the wrong thing for this motor, as stated in the OP it is rated for 220V delta 380V star
 

Reply to Single Phase 230V supply and 3ph Compressor install. in the Commercial Electrical Advice area at ElectriciansForums.net

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