480 to 240volt or 208volt

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AC\DC

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Hvac installer put in a 208/240 3/0 unit. I have 480/277 3/0.
Wed a transformer. Seems since they’re no neutral to this unit that 240volt delta 3/0 would be best.
Just want to double check.
 
AC\DC said:
Seems since they’re no neutral to this unit that 240volt delta 3/0 would be best.
Click to expand...

Although you don't need a neutral, a 480 - 240/139V transformer is another possubility. It gives you balanced L-G voltages in case there is circuitry in the unit that could be sensitive to this, for example MOV surge suppressors in a VFD. If that was true, though, I'd expect the installation instructions to mention it.

store.maddoxtransformer.com

3-Phase 480 D - 240 Y 139 (Drive Isolation Transformer)

Drive-Isolation transformer converts 3-Phase 480D to 240Y/139. These units can handle demanding AC/DC variable speed drives and provide needed voltage change.
store.maddoxtransformer.com store.maddoxtransformer.com
 
HVAC systems are becoming more inverter based, and inverters prefer grounded wye supplies.

This is not as much a problem in the 200V class, but something to consider.

I'd probably go with 208/120V unless there was a performance hit or significant wiring cost change.
 
Even though the unit does not need a neutral, it may have a drive. I would go with a 120.240 secondary so you will have the neutral reference.
(or the two previous posts that popped up as I as typing :) )
 
augie47 said:
Even though the unit does not need a neutral, it may have a drive. I would go with a 120.240 secondary so you will have the neutral reference.
(or the two previous posts that popped up as I as typing :) )
Click to expand...
I am surprised by how many electricians become somewhat confused when they have to work on systems that do not have 'solid' Line-Neutral and Line-Ground connections tions, so I like to include neutrals.
 
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