Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
(OP)
Hi,
I am trying to design an Industrial Control Panel that will replace an older Control Panel that is currently being used in a machine control application. I have posted a several questions related to this project, and the responses I have received have been incredibly helpful. If everyone here hasn't grown too tired of me by now, I have one more...
While the new components I'll be using in the new panel in most cases are a bit smaller than the old components in the old panel, I have found that the old panel has virtually no branch fusing. The only over-current protection for many of the components inside the panel is from the main circuit breaker that supplies the entire panel. In the new panel, I am planning to include branch fuses for each individual component. This has resulted in my current (preliminary) panel layout being more cramped than I would like it to be.
One opportunity I thought of that would free up some space would be if I could eliminate a transformer in the old panel that takes the 208 VAC supply voltage down to 115 VAC for a few components that require the lower voltage. I will have components in the new panel that will require 115 VAC, but I am wondering if the facility can provide me with a four wire 208 VAC supply circuit (3 phase plus neutral), if I can get the 115 VAC I need between one of the phase lines and the neutral.
Before I consider doing this (and asking our electrical contractor if he can give me the neutral, which is not in use on the old panel), I figured I'd ask here if there are any drawbacks I should consider if I think about going this route.
Any advice will be greatly appreciated.
Thanks in advance,
Paul
I am trying to design an Industrial Control Panel that will replace an older Control Panel that is currently being used in a machine control application. I have posted a several questions related to this project, and the responses I have received have been incredibly helpful. If everyone here hasn't grown too tired of me by now, I have one more...
While the new components I'll be using in the new panel in most cases are a bit smaller than the old components in the old panel, I have found that the old panel has virtually no branch fusing. The only over-current protection for many of the components inside the panel is from the main circuit breaker that supplies the entire panel. In the new panel, I am planning to include branch fuses for each individual component. This has resulted in my current (preliminary) panel layout being more cramped than I would like it to be.
One opportunity I thought of that would free up some space would be if I could eliminate a transformer in the old panel that takes the 208 VAC supply voltage down to 115 VAC for a few components that require the lower voltage. I will have components in the new panel that will require 115 VAC, but I am wondering if the facility can provide me with a four wire 208 VAC supply circuit (3 phase plus neutral), if I can get the 115 VAC I need between one of the phase lines and the neutral.
Before I consider doing this (and asking our electrical contractor if he can give me the neutral, which is not in use on the old panel), I figured I'd ask here if there are any drawbacks I should consider if I think about going this route.
Any advice will be greatly appreciated.
Thanks in advance,
Paul
RE: Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
RE: Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
RE: Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
RE: Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
RE: Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
I know it makes perfect sense to be ABLE to do that, but the real world often does not make perfect sense.
" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
RE: Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit
While 208Y/120 is available in the building where this will be installed, I am sure that a 4 of 5 conductor cable has not been pulled to the existing control panel. This means that if I don't include a control transformer in my new panel, I will need our electrical contractors to pull new wires and possibly replace the existing conduit with something larger. I was not aware of the fact that using a control transformer makes it easier to satisfy SCCR requirements. This is useful information. While I know I won't be subjected to UL inspections or to come up with a SCCR for this particular project, I am trying to comply with current UL guidelines to whatever extent I can, with the hope that I might be able to use this panel as the prototype for other panels that might be installed in other locations with more stringent requirements.
For now, I will do my best to arrange my components efficiently in a way that will allow ample space for a control transformer, without having to go to a larger enclosure size than the original panel I will be replacing (which would be difficult due to space constraints). If I can't do it, now I feel like I understand the pros and cons of eliminating the control transformer.
I really appreciate all your help.
Thanks again,
Paul
RE: Eliminating 208 to 115 VAC transformer by using phase to neutral from supply circuit