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480V vs. 600V systems
- Thread starter camfink
- Start date
In theory 600 V system will be more efficient and have fewer losses. For the same kVA, smaller wire sizes can be used, voltage drop will be less of a concern. There is really not much theoretical advantage to 480 V over 600 V, since 600 V insulation is used for both.
In practice, the differences are not huge and the decision is largely driven by local custom and compatibility with existing equipment. In the US, there are not many 600 V systems, while it is much more common in Canada.
If everyone was starting over, we'd probably go with 600 V.
In practice, the differences are not huge and the decision is largely driven by local custom and compatibility with existing equipment. In the US, there are not many 600 V systems, while it is much more common in Canada.
If everyone was starting over, we'd probably go with 600 V.
- Thread starter
- #3
The main advantage of higher voltage 600V vs. 480V is lower current for the same amount of power meaning less cabling and conductors. I am currently doing a project that is utilizing 600V distribution within the facility because of the power requirements. The draw back though has been there is less equipment options for 600V than at 480V which is more common. Also depending on the loads 600V systems may require installtion of more transformers. For systems that have large connected load I would recommend using a MV distribution system (ie 5kV and up)
No there is no additional danger in using 600V vs 480V in hazardous areas. Once you go over about 10V, the difference in voltage is irrelevant in terms of ignition.
Bottom line, if you are in Canada, 600V is OK because there are a lot of other 600V users there. If you are in most of the US, it will be problematic in terms of finding motors, drives, lighting fixtures etc. In fact with lighting, using a 480Y277V 4 wire system has advantages in that you can use 1 phase to neutral for much of your lighting equipment because lots of manufacturers provide 277V ballasts. With 600V, you need to buy a transformer to run your lighting systems in most cases, and transformers cost money plus drop efficiency. There are a few ballast manufacturers now selling 347V ballasts in the US, but again, limited options.
Bottom line, if you are in Canada, 600V is OK because there are a lot of other 600V users there. If you are in most of the US, it will be problematic in terms of finding motors, drives, lighting fixtures etc. In fact with lighting, using a 480Y277V 4 wire system has advantages in that you can use 1 phase to neutral for much of your lighting equipment because lots of manufacturers provide 277V ballasts. With 600V, you need to buy a transformer to run your lighting systems in most cases, and transformers cost money plus drop efficiency. There are a few ballast manufacturers now selling 347V ballasts in the US, but again, limited options.
I have been told that the impedance and 'other' aspects make 600V systems more likely to burn via sustained low current arcs. I was then pointed to a job our company did for El Paso Gas (controlling transmission valves) where our stuff was incinerated along with everything else when a 600V arc started in a piece of equipment then burned back down 300 feet of conduit into an equipment room toasting everything within 6-8 feet of the 600V cabling. It was before my time, with that company, so I don't have personal experience with that disaster. Is there any truth to this 600V arc tenacity? It might relate to the OPs question.
Keith Cress
Flamin Systems, Inc.-
Keith Cress
Flamin Systems, Inc.-
For hazardous areas, I guess don't see any difference and the codes make no distinction. You can blow yourself up with 50 V in the right mixture of gases.
Arcing faults could be another matter. It's an interesting question. I suspect 480 V might actually be worse for arcing faults since the 277V is right in the sweet spot for a self-sustaining arc that just keeps going and going. Both 480 V and 600 V having arcing ground fault issues that have to be dealt with. But there have been hundreds and hundreds of fires started by 480 V ground faults so I doubt that any differences are really dramatic. 600 V is used widely in the pulp and paper mills in Canada and even in the US.
Arcing faults could be another matter. It's an interesting question. I suspect 480 V might actually be worse for arcing faults since the 277V is right in the sweet spot for a self-sustaining arc that just keeps going and going. Both 480 V and 600 V having arcing ground fault issues that have to be dealt with. But there have been hundreds and hundreds of fires started by 480 V ground faults so I doubt that any differences are really dramatic. 600 V is used widely in the pulp and paper mills in Canada and even in the US.
- Thread starter
- #11
camfink; See JBinCA's response. Oil fields are often seat-o-the-pants operations relying on local supplies for hardware. 460 is way more likely to be found on a local shelf because of the 230/460 relationship lacking with 600.
Keith Cress
Flamin Systems, Inc.-
Keith Cress
Flamin Systems, Inc.-
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- #13
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- #14
Hi itsmoked.
I think that the sustained arcing issue is more an issue of improper protection rather than 480V/600V. I have seen pictures of similar damage caused by a sustained arc on 480 volts.
Such incidents are probably the driving incentive behind the NEC and CEC requirements for ground fault protection on large services and feeders. (CEC=Canadian Electrical Code for those of you in California)
respectfully
I think that the sustained arcing issue is more an issue of improper protection rather than 480V/600V. I have seen pictures of similar damage caused by a sustained arc on 480 volts.
Such incidents are probably the driving incentive behind the NEC and CEC requirements for ground fault protection on large services and feeders. (CEC=Canadian Electrical Code for those of you in California)
respectfully
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