Single to 3 phase

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nyerinfl

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Broward Co.
I'm trying to figure out a cost effective way to get 3-phase from single phase. A job I'm getting they want to install these ovens for cooking pottery which draw about 50 amps at 3-phase 208. Problem is I only have single phase 208. Upgrading service is a costly option, but I've been looking into phase converters and the like and they seem like they would cost just as much as a service upgrade (I need two). Any ideas?

A generator would not be a realistic option, this is future retail.
 
If you have single phase, 208, are you sure there's not 3-phase someplace on the property? It seems like these 208 services often present as 3-phase, then they peel off single phase services to each tenant. I'd go for the service upgrade and not a phase converter if possible. I save the phase converters for where getting real 3-phase is impossible.
 
480sparky said:
208 volts is usually what you have between two ungrounded conductors on a three-phase system......
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You and MDShunk are both correct. There is 3-phase on the property, but the meter room is a good 175-200 ft away, making it like I said a costly option. Wasn't sure if maybe there was some possible way to do this that I was missing, short of upgrading the service.
 
Well you could go with a phase converter but I would be surprised if that is cheaper then running the 200' back to the three phase.
 
iwire said:
Well you could go with a phase converter but I would be surprised if that is cheaper then running the 200' back to the three phase.
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It seems that way. I guess it's good news for me, bad news for the customer.
 
nyerinfl said:
I'm trying to figure out a cost effective way to get 3-phase from single phase.
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While I agree that it can be done, the serving electric utility may not let you do it. We have a limit on the size of 208 volt, 1? services so we can keep the load on transformers balanced. I would bet that other electric utilities have something similar. I recommend a meeting with the serving electric utility before proceeding with anything. :)
 
nyerinfl said:
You and MDShunk are both correct. There is 3-phase on the property, but the meter room is a good 175-200 ft away, making it like I said a costly option. Wasn't sure if maybe there was some possible way to do this that I was missing, short of upgrading the service.
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If 3-phase is truly available, then it's best (IMPO) to use it instead of a phase converter. Phase converters are machines, and machines are prone do breakage. It may cost more to go the 200 feet and redo some of the service, but in the long run, I'd say copper is a lot more reliable than a machine.
 
In the long run with the efficiency of the converters...run it back or contact the manufactures to see if they have an approved rewire of the elements for single phase.
 
nyerinfl said:
I'm trying to figure out a cost effective way to get 3-phase from single phase. A job I'm getting they want to install these ovens for cooking pottery which draw about 50 amps at 3-phase 208.
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If you chose to run the 3 phase conductor 200 ft, the 3% VD will require
#4 for 50 amps
#2 for 100 amps
#1/0 for 150 amps.
VD will be critical for those ovens to reach the required temperature.
 
brian john said:
...or contact the manufactures to see if they have an approved rewire of the elements for single phase.
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Now there's an idea worth pursuing. Heating appliances often have the possibility to move some nickel or brass jumpers around to make them single phase. If the ovens have blower motors, however, this isn't really a good possibility.
 
You should also keep in mind that you'd need a lot more current on single phase to get 50a 3-phase. Even rewiring the oven for single phase will require more current for the same heating power, but still it's my first preference, also.
 
bob said:
If you chose to run the 3 phase conductor 200 ft, the 3% VD will require
#4 for 50 amps
#2 for 100 amps
#1/0 for 150 amps.
VD will be critical for those ovens to reach the required temperature.
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Wouldn't you have to figure the circuits that are 100A or less based on the 60 degree column and the 150A circuit at 75 degrees? #2 is listed as 95 Amps @ 60? and 1/0 is listed as 150A @ 75?. This is without doing a VD calc. Am I looking at 110.14 C 1 correctly?
 
bob said:
VD will be critical for those ovens to reach the required temperature.
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I disagree, unless these ovens where designed very cheaply they will have enough heating to reach the required temp even with 10% VD.

They will have thermostats that control the temperature, it is very unlikely they where designed to run on continuously to hold a certain temp.

Of course the time to reach full temp may be longer.
 
kpepin said:
Wouldn't you have to figure the circuits that are 100A or less based on the 60 degree column.
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Yes ... unless the terminals are rated 75 C and there is an very high chance they will be. Very little equipment has 60 C terminals.
 
iwire said:
I disagree, unless these ovens where designed very cheaply they will have enough heating to reach the required temp even with 10% VD.

They will have thermostats that control the temperature, it is very unlikely they where designed to run on continuously to hold a certain temp.

Of course the time to reach full temp may be longer.
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OK. I agree.
 
Now there's an idea worth pursuing. Heating appliances often have the possibility to move some nickel or brass jumpers around to make them single phase. If the ovens have blower motors, however, this isn't really a good possibility.
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Years ago we had the same situation, customer bought the wrong voltage commercial replacement dryer. We rewired the dryer, obtained new motor from manufacture, upgraded branch circuit. Customer had a fit at the bill, my bosses response, "I told you it would be cheaper to buy the correct dryer."
 
charlie said:
I recommend a meeting with the serving electric utility before proceeding with anything. :)
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Agreed and would strongly recommend as well. When I was in Indy IPL, Cinergy, Hendricks Power, etc. were great to work with, as an example.
 
dcspector said:
When I was in Indy IPL, Cinergy, Hendricks Power, etc. were great to work with . . .
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AWWWW shucks.
embarrassed002.gif
 
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