Single phase 120/240 to 3phase 240/120

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AC\DC

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Location
Florence,Oregon,Lane
Occupation
EC
HVAC contractor called he ordered wrong equipment. Supply voltage is 120/240 single phase
Equipment is 240/120 3 phase
Told him he could use a rotary phase converter.( I personally have never seen or used)
Another option i through his way, was to see what exactly need the three phase in the equipment and change it out to single phase unit. Voids warranty but I am not hocking up
;)
Any other option?
Never had to do this before.
 
How special order is the HVAC unit he got by mistake?
I think it's extremely unlikely that providing 3-phase to his equipment will cost less than getting the right equipment and finding another home for what he bought by mistake.
 
Just how large an HVAC unit are we talking about?

Does it have 3 phase hermetic compressors and fans, or does it have internal VFDs?

-Jon
 
I’ll have to ask him exactly what hearing unit. To size rotary phase transformer is it double the three phase amperage. Read a couple post in this.
Would the transformer cost a lot. Never bought one.
 
AC\DC said:
I’ll have to ask him exactly what hearing unit. To size rotary phase transformer is it double the three phase amperage. Read a couple post in this.
Would the transformer cost a lot. Never bought one.
Click to expand...
I don't know what a rotary transformer is, but you cannot make three phase from single phase with simple transformers. There's no way that I know of, anyway.
 
While phase converters have their place in limited applications, in my view this is not one of them. For this kind of application I think it is a terrible idea for a number of reasons. Unless you have some other compelling reason, changing the service to 3 phase is probably not a viable idea either.
I'm always amazed how often wrong equipment is ordered. It's inexcusable and the guilty party needs to step up and get the right equipment for the job.
 
AC\DC said:
I’ll have to ask him exactly what hearing unit. To size rotary phase transformer is it double the three phase amperage. Read a couple post in this.
Would the transformer cost a lot. Never bought one.
Click to expand...
Per the 'laws of physics', you cannot use a an electromagnetic transformer to get from single-phase to three-phase.

You can use a phase converter to go from single-phase to three-phase. There are static types, rotary types, and electronic types. In +40 years I have only been involved with a few installations. In general I would send electricians direct to the phase converter companies. Most customers going this route seemed not to want to pay for my engineering.
 
jim dungar said:
Per the 'laws of physics', you cannot use a an electromagnetic transformer to get from single-phase to three-phase.

You can use a phase converter to go from single-phase to three-phase. There are static types, rotary types, and electronic types. In +40 years I have only been involved with a few installations. In general I would send electricians direct to the phase converter companies. Most customers going this route seemed not to want to pay for my engineering.
Click to expand...
Yeah, don’t go by the hp rating the manufacturer of the rotary converter that says it will run, found that out after the machine arrived, and the documentation said to get one twice as big. The one that I had was rated for the motor, but took too long to start the motor, and trip out the overloads. Just priced out a couple for a job coming up, and it was $8000 just for two converters and the voltage stabilizers the manufacturer called for. An industrial park with only single phase, go figure! LOL!
 
hillbilly1 said:
Yeah, don’t go by the hp rating the manufacturer of the rotary converter that says it will run, found that out after the machine arrived, and the documentation said to get one twice as big. The one that I had was rated for the motor, but took too long to start the motor, and trip out the overloads. Just priced out a couple for a job coming up, and it was $8000 just for two converters and the voltage stabilizers the manufacturer called for. An industrial park with only single phase, go figure! LOL!
Click to expand...
The unstabilized created phase from a rotary converter (rotary transformer??) can be wildly out of nominal voltage, and any significant voltage imbalance can cause an ever greater (percentage) current imbalance in the motor, which in turn risks damaging the three phase motor, or tripping the overloads,even after starting. Hence the need for "voltage stabilizers", whatever they may be. And the importance of properly sizing the converter.
The more expensive the motor, the greater the risk when using a rotary converter.
 
I would not use a phase converter for this application. Across the line HVAC compressors operate at very near full load when they are running (cycling on and off per thermostat control). Any imbalance in the supply voltage will push them even hotter than normal.

Jon
 
Well. Did not hear from him since this question until yesterday. He could not fiqure out how to make a contact close.
Went to help him out and found out he got the phase converter, he had the company size it for him. I told him he asking for trouble especially if he has any power quality issues since he out on the wild yonder.he said it’s heating wonderfully , I told him it’s the compressor for cooling that going to be a problem o well I did not touch it lol

He got no permit wiring a mess unites 6k and the phase converter was 2k.
Don’t know why he just did not get the right unit.
 
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