How to operate a 3-ph, 440V equipment using 1-ph, 230V supply?

[Groovster]

As the title states, I've been having trouble figuring out how to run a certain large dryer for corn and rice due to the available supply in our locality.

The dryer is a modular equipment that runs at a total of 30-hp and requires a 440V, 3-phase supply. The only available supply is 230V, single phase.

A friend suggested running it by connecting the system as follows: supply-transformer-phase converter-dryer OR supply-phase converter-3ph transformer-dryer.

Costing aside, will this be a feasible option? Are there any other cheaper ways to run the dryer?

I will greatly appreciate your help on this matter. Thank you.

 

[chaoseverlasting]

I think it'll be easier and cheaper to work with a 1ph xmer. Other than that, though theoretically it sounds feasible, I don't have any practical experience in this sort of thing. Another thing, since you're working at line power levels (or at least significantly above analog electronics power levels), you're going to have to find accurate inductors for the phase converters, which is going to be a pain.

I don't know if this particular method would work in this case, but for my guitar effects, I had once used the primary of a transformer as an inductor. Again, I don't know if it would be economically feasible to use an extra transformer as an inductor.

If you do decide to go this route, another thing you can look at are choke coils as inductors, but you're going to have to compare prices and values of what else is available. Maybe you could raid a junkyard?

 

[vk6kro]

This will be expensive and you should not ask for advice on Internet. Get local expert opinion even if you have to pay for it.

30 HP is about 22371 watts or 99 amps at 230 volts, so any conversion of single phase to 3 phase is going to take even more current than that. This is serious current and the conversion to 3 phase would require some expensive hardware.

If cost is no object, could you consider getting a 35+ HP gasoline or diesel 3 phase generator?

But get local advice. It may be better to convert to gas heating.

 

[Averagesupernova]

The biggest single phase transformer you can get in my locality is 50KVA for 240 volt service. My power supplier said to figure about 1KVA per horsepower. If they provide service in your area the same way they do in mine, you will not be that far away from maxxing out your transformer and then you have to figure a bit of loss to step the voltage back up to 440 and generate 3 phases. I would say you would be better off having your supplier get you a 440 volt single phase service (assuming 3 phase is not available at all) and get a phase convertor to do the rest.

 

[schip666!]

By using the word "dryer" it sounds to me that you may have two things to power, a motor and some kind of heater -- presuming it is electrical. If that is the case, you may be able to swap out the motor (which I'd bet uses the lesser part of the juice) for a single phase version, and jerry-rig the heater to somehow run on what's available? Otherwise I think a very-expensive phase converter, or a perhaps-less-expensive generator are your only options.

 

[Averagesupernova]

I'm pretty sure what he is talking about uses a propane or natural gas burner for heat. Probably in the range of 3 to 12 million BTU.

 

[chaoseverlasting]

This will be expensive and you should not ask for advice on Internet. Get local expert opinion even if you have to pay for it.

30 HP is about 22371 watts or 99 amps at 230 volts, so any conversion of single phase to 3 phase is going to take even more current than that. This is serious current and the conversion to 3 phase would require some expensive hardware.

Shouldnt it take less current?

Since rated power drawn is independent of phase etc

p(1ph)=v*i*cosw=P(3ph)=1.732V*i*cosw'

Since we're stepping up voltage to 440, the 3ph line current comes roughly to 30A.

 

[sophiecentaur]

This is a typical 'Engineering' problem and the optimum solution will depend on the actual costs involved.
A. A motor-generator set would be one solution. Single Phase motors are available and so are small three phase generators. Sounds very clunky but, as an alternative to a very crude and inefficient single to three phase transformer (were they called 'Scott transformers'?) it could be an nicely understandable solution with a lot of available equipment sources.

B. You could use a solid state rectifier / inverter set but that sounds V expensive for high power - although efficiency could be better than the 'rotational solution'.

Plan C (schip666's) would be to use a different dryer or change the motor in the existing one. The heating elements would not mind a single phase supply but would need rewiring by an EXPERT! It would get my vote under most circumstances.

 

[Averagesupernova]

Scott-Tee transformers will not convert between three phase and single phase. They can convert between 2 signals that are 90 degrees apart and the standard 120 degree 3 phase in question.
-
As I said, I am about 100% sure the dryer in question will NOT use an electric heater.

 

[vk6kro]

Shouldnt it take less current?

Since rated power drawn is independent of phase etc

p(1ph)=v*i*cosw=P(3ph)=1.732V*i*cosw'

Since we're stepping up voltage to 440, the 3ph line current comes roughly to 30A.

Not really. There is only one supply, 230 volts.
So, any extra power used due to losses etc will draw more current from the 230 volt supply.

Horse power is a mechanical output unit, so this implies that there would be extra power used due to the losses in whatever is producing the 30 HP.
So, the point was that 99 amps would be a minimum current used and that it would probably be a fair bit higher than that.

Groovster seems to have vanished anyway.

 

[Groovster]

I haven't really vanished. I've been keeping track of this and doing some readings so that I could avoid asking unnecessary or silly questions. My knowledge in this field is pretty mediocre.

Yeah the original plan was setting up the phase converter system. Different wire sizes are supposed to be used because the currents differ from one device I/O to others. The largest current is definitely from the 1-ph source and pretty much around vk6kro's estimate but starting of the equipment still needs to be considered.

Just for specifics, the components of the dryer are: 20HP hot air blower, 3HP cool air blower, 4HP grain agitator, 1.5HP feed regulator and a 1HP screw conveyor. All run on 440V, 3-ph source and the dryer uses kerosene or diesel fuel. I haven't seen the actual equipment yet, only in pictures.

Thanks for all the feedback guys. I'm trying to explore all options you've given me. Another person suggested that I use a transformer and individual VFDs for each component. I'm not sure how VFDs can act like a phase converter so maybe you could enlighten me on this.

 

[vk6kro]

So, the main heating comes from burning the kerosene or diesel fuel or is it used to generate electrical power which then does the heating?

Just curious, which country are you in?