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

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

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

(OP)
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.

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

Yes, it is feasible. Another option would be to use an appropriately sized VFD (read oversized). Search this website on the topic.

As for cheaper or not, you need to compare the costs. If high tech maintenance and service/troubleshooting is an issue in the remote area, I would stay with low tech but robust phase converters.

Regardless, 30 HP is too much for a single phase 230V supply, you need to make sure that service transformer is big enough. Work with your utility co.

Rafiq Bulsara
http://www.srengineersct.com

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

Put a PTO driven generator on the back of your tractor. You need 25 KVA or  30 KVA. 50 KVA or 60 KVA would be better.
 

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

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

As rafiq says, 30HP is a lot of power for an average commercial 230V 1 phase system, way way too much if it is a residential service. To do this without some method of serious current limitation, such as VFDs, you will need the supply to be capable of that 50kVA mentioned by Bill (I don't believe you could get away with less).

Your options:
1) Transformer + Rotary Phase Converter = very inefficient but possible to run multiple motors from one large system. But you may have trouble starting the "idler" for a single system that size from that 1 phase supply.

2) Transformer + Static Phase Adder = More efficient, less flexible in terms of it's ability to start and stop multiple downstream motors, still does nothing to soft start the load so still may be a problem for that 1 phase supply at that size. If the loads can stagger-start, maybe you can use multiple Static Phase Adders to get around that.

3) Transformer(s) + VFDs. This is the best suggestion I can give you without knowing a whole lot more than what you have provided. Evaluate the motor power requirements for each "module" and use a transformer to go from 230 to 460V single phase, then put an appropriate 480V rated VFD for each of the motors. Each VFD will need to be twice the size of the motor, i.e. if you have a 5HP motor, you need a 10HP VFD. Do not attempt to use one large VFD if you have separate motors that need to come on and off independently, you will kill the VFD in short order (similar issue as a single Static Phase Adder by the way).


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

If you really have no options for the proper 440V supply, a rotary phase converter and transformer might be the option to go with.  They are easy, robust, and require almost zero maintenance.  As mentioned, they are not very efficient.  I would likely opt for the transformer - phase converter - load, if only because I don't know where you'd obtain a 230V motor to use as a phase converter for a 30 KVA load.  It also might be a good idea to place a high inertia drum on the phase converter to help with start up of the dryer.



 

------------------------------------------------------------------------
If it is broken, fix it.  If it isn't broken, I'll soon fix that.

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

(OP)
Sounds like using VFDs is a promising option. I'm sorry if this question would seem silly but I'm not exactly sure how VFDs could act like a phase converter. Could you enlighten me on this?

The tractor driven generator also seems a good option. Will this set-up be efficient, if not cheaper?

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.

Thanks for all the feedback guys, I'm exploring all options you've given me.

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

I would investigate the cost of a diesel powered generator set. Since the dryer is fueled by diesel/fuel oil, that choice would make most sense.  

The use of an engine is not very efficient if you count the btu content of the fuel and the power you get out of the generator, but in your situation, you should be able to route the heat from the radiator and the exhaust from the diesel into the the air stream for the dryer and capture the "waste" heat (greater than 50% of the BTU contained in the fuel) which is normally lost.  

It would just take some creative thinking about how to route the cool intake air through the generator enclosure first and then across the engine and then out the radiator (pusher fan is pretty standard on generator sets) and into the intake of the dryer.  I don't know if you can stand the exhaust in there (routed in after the radiator and the fan motor)because of soot particles, but since it burns diesel as the main source of heat, probably you could work it out.   

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

Is drying time critical in this application or is that much air needed for a fluidized bed?  Going to a smaller hot air blower would make this easier to do.  Just curious how these driers work.  Why is the cool air blower separate?

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