XL Automation
Member
- Location
- Marietta, GA, USA
Hello;
I design automation and control panels for manufacturing plants. I am designing a piece of equipment that will be portable, and could end up either in Europe or the US. The control panel is fed by 480 or 400VAC 50/60HZ 3 phase power. The panel contains some variable frequency drives, programmable controller, etc. The majority on control/logic voltage in the panel is 24VDC, generated from a power supply in the panel. The variable frequency drives will operate at either 400 or 480VAC. There is a control transformer in the panel that is rated at 50/60HZ and has 400 and 480VAC primary taps for US/European use. The secondary is 240x120 The question I have revolves around the few devices in the panel that operate at 220-230VAC single phase.
If I were designing this panel for US only use, I would wire the transformer for 240/120 such that I have two 120v to neutral phases and 240 between the phases. Then I would use either 120 or 240VAC power as needed. Anything being fed via 240VAC would have a two-pole breaker, obviously. Since this panel is for potential European use, I don't want to use the 120VAC at all. My initial thought (and how I originally designed the panel) was that I wire the transformer the same, but I just didn't use the neutral for anything. All 240VAC circuits would of course be 120VAC to ground and would be feed from two pole circuit breakers.
I believe in Europe, 220-240VAC circuits have 240VAC to ground and the second conductor is 0V to ground (i.e. a neutral). If I were building this panel for strictly European use, I would ground one of the 240VAC secondary legs on the transformer instead of the center tap and all of my 240VAC control circuits would require single pole breakers.
My question is that would this be acceptable to do this in the U.S.? On first glance, I don't see anywhere in the code that this would be disallowed. I simply have a 240VAC control circuit voltage with one hot conductor and one neutral. For U.S. use, I would have a placard that alerts any technician that control voltage is 240VAC.
I appreciate any help or suggestions. I don't want to seem like an idiot, but I simply have never come across this before, having always built panels with 120VAC control power.
Thanks,
Michael
XL Automation, Inc.
I design automation and control panels for manufacturing plants. I am designing a piece of equipment that will be portable, and could end up either in Europe or the US. The control panel is fed by 480 or 400VAC 50/60HZ 3 phase power. The panel contains some variable frequency drives, programmable controller, etc. The majority on control/logic voltage in the panel is 24VDC, generated from a power supply in the panel. The variable frequency drives will operate at either 400 or 480VAC. There is a control transformer in the panel that is rated at 50/60HZ and has 400 and 480VAC primary taps for US/European use. The secondary is 240x120 The question I have revolves around the few devices in the panel that operate at 220-230VAC single phase.
If I were designing this panel for US only use, I would wire the transformer for 240/120 such that I have two 120v to neutral phases and 240 between the phases. Then I would use either 120 or 240VAC power as needed. Anything being fed via 240VAC would have a two-pole breaker, obviously. Since this panel is for potential European use, I don't want to use the 120VAC at all. My initial thought (and how I originally designed the panel) was that I wire the transformer the same, but I just didn't use the neutral for anything. All 240VAC circuits would of course be 120VAC to ground and would be feed from two pole circuit breakers.
I believe in Europe, 220-240VAC circuits have 240VAC to ground and the second conductor is 0V to ground (i.e. a neutral). If I were building this panel for strictly European use, I would ground one of the 240VAC secondary legs on the transformer instead of the center tap and all of my 240VAC control circuits would require single pole breakers.
My question is that would this be acceptable to do this in the U.S.? On first glance, I don't see anywhere in the code that this would be disallowed. I simply have a 240VAC control circuit voltage with one hot conductor and one neutral. For U.S. use, I would have a placard that alerts any technician that control voltage is 240VAC.
I appreciate any help or suggestions. I don't want to seem like an idiot, but I simply have never come across this before, having always built panels with 120VAC control power.
Thanks,
Michael
XL Automation, Inc.