ECN Forum Forums Code Related Discussion Canadian Electrical Code Topics 347 lighting

With the plans to upgarde in the next few years, a poer upgrade at this point seems to be the most logical course of action. Thats what he's planning to do now.

thanks for your help guys.

Clyde

Given a power upgrade is in the future, there is some merit in maintaining a 3phase delta system. Harmonics, efficiency ground fault protection and other topics come to mind.

For those circuits that are in need of a 347 volt source and given there are times when the load is not balanced, an artificial neutral may be a consideration. The auto transformer connections provided by Bjarney appear to provide an artificial neutral but "tuning" may be a problem. Any change in load characteristics re: size or load sharing may be an issue. As well, the capital cost of the 1.5 kva xformers may be about the same cost as 22.5 kva delta/star dry core 1/1 ratio transformer.

I should ask what the rural voltage in Clyde's area is. Is there 600 volt 3P4W primary easily available or will the upgrade have to deal with a 3P3W in any event? Wiull the local utility provide a 4 wire system but at what cost?

I know in a lot of Rural Ontario 3P3W @600 volt is a local utility voltage -- 4160 on up to 35KV and a transformer allowance as part of bigger projects.


Just thinking out loud.....

Doug.....et al

I must disagree with the need for “tuning”. For all practical purposes, the ZZA set should be able to efficiently operate 20 fixtures [24 amperes at 347V] on one phase-to-derived-neutral connection. That is one of the accepted capabilities of grounding transformers for serving potentially unbalanced loads.

I hear ya!!1

I guess I was looking at a standard off-the-shelf method of an economical code
approved device with some extra capacity. Some of the inherent problems of ground fault etc are important factors as well.

There are so many options one has to be selective to ones immediate process.

Although FPE is not a very good example because of some bad history in the US but the following URLS are interesting to review.

This URL is the Canadian arm of Schneider. They have a good write up on the subject as well.
http://www.schneider-electric.ca/www/en/products/ground/html/general.htm

Section 4 of the PDF file at the following URL is interesting from Powercon Corp of Maryland.
http://www.powerconcorp.com/docs/pcib-1031.pdf

Doug......et al