208V single phase (2 phase) for 240V single phase load?

[montericci]

A WWTP has a lab drying oven that is rated at 240V + or - 10%, 2.1A.
We've designed a new lab for the wastewater treatment plant.
I have specified to have the electricians install a new 120/208Y panel in the new lab.
There are a couple of 208V, 3 phase new devices spec'd for this new lab and this panel should be able to handle single phase loads as well.

But, will the 208V, 2 phase (2 pole breaker) be sufficient to operate the dryng oven or do I need to go back to the drawing board?
Unfortunatly the panel has been purchased already and this one device was an oversight on my part.

 

[kwired]

Heater will still operate but will be at less wattage. If this is not acceptable then you may consider buck/boost transformer. Other thing to keep in mind may be voltage rating of any controls and if 208 is acceptable for those.

 

[nakulak]

240v - 10% is 200v, so I don't see the issue.

 

[augie47]

240v - 10% is 200v, so I don't see the issue.

new math ?

 

[Jraef]

As kwired said, the heater element, assuming resistive and assuming it was wired to 240V directly*, will put out less heat at full power. So for example if you have a heater element rated for 1500W at 240V and you give it only 208V, it is only going to put out the equivalent heat of a 1300W heater element. In a dryer, that means it will theoretically have to run longer to do the same work. But most dryers have a moisture sensor anyway, and the heater element is going to cycle on and off as necessary, so the difference may not even be noticable to the end user.

*Because of the common issue of 208V vs 240V systems, it's somewhat common for the heater elements in things like this to actually be 2 x 120V, meaning two separate heaters that are connected Line to neutral. That way if they are fed 240V 1 phase and a neutral, or 2 legs of 208V 3 phase and a neutral, the heater elements work exactly the same. A quick way to tell is by looking at the connections. If you are required to connect a Neutral, it's likely wired this way. If you only have to supply 2 hot legs and a ground, then it is NOT going to be wired this way.

 

[Hv&Lv]

A WWTP has a lab drying oven that is rated at 240V + or - 10%, 2.1A.
We've designed a new lab for the wastewater treatment plant.
I have specified to have the electricians install a new 120/208Y panel in the new lab.
There are a couple of 208V, 3 phase new devices spec'd for this new lab and this panel should be able to handle single phase loads as well.

But, will the 208V, 2 phase (2 pole breaker) be sufficient to operate the dryng oven or do I need to go back to the drawing board?
Unfortunatly the panel has been purchased already and this one device was an oversight on my part.

I agree with the others if it is heat only. What I am so unsure of is why so picky about the voltage if it is just resistance heaters? Is there a special motor on the unit like a convection oven?

 

[jmellc]

I remember installing small b/b transformers for some heating eqpmt in a foam plant. I think Square D made them. Fairly small, fit onto control cabinet & chase nippled them through the bottom to connect. Could be used for many in/out voltages. See if the eqpmt does OK as is, then try b/b txf if needed.

 

[david luchini]

new math ?

I love me the new math. So does Jraef.

As kwired said, the heater element, assuming resistive and assuming it was wired to 240V directly*, will put out less heat at full power. So for example if you have a heater element rated for 1500W at 240V and you give it only 208V, it is only going to put out the equivalent heat of a 1300W heater element.

I think 1125W would be more like it. You'd get a reduced power output in relation to the ratio of the voltages squared. (208/240)^2 = 0.75.

 

[bob]

240v - 10% is 200v, so I don't see the issue.

You might want to trash that calculator and get a new one.

 

[david luchini]

But, will the 208V, 2 phase (2 pole breaker) be sufficient to operate the dryng oven or do I need to go back to the drawing board?
Unfortunatly the panel has been purchased already and this one device was an oversight on my part.

If you only have a couple of these drying ovens, you could always install a buck-boost transformer for each to boost the voltage up to 240 for each oven, if they had trouble operating on 208.

 

[Cow]

You might want to trash that calculator and get a new one.

What if he used his brain?

 

[kwired]

I agree with the others if it is heat only. What I am so unsure of is why so picky about the voltage if it is just resistance heaters? Is there a special motor on the unit like a convection oven?

Motor is more likely to operate with same performance at either voltage, it will just draw more current at 208 volts. A heating element will have 25% less heat. If proper heat is critical to a process this could be a problem if the reduced wattage can not keep up with the process demands.


OP said his unit was 240 volt 2.1 amps. That is about 500 watts. At 208 volts it will be about 375.