2 pole breakers on a single phase NER circuit.
2 pole breakers on a single phase NER circuit.
(OP)
Recently we installed NER's on three 11/0.433kv power transformers supplying a coal processing plant. This modification was performed to overcome a design fault that was not picked up till 2 years after commissioning. I have been informed that I require 2 pole circuit breakers on all single phase circuits. I have consulted various Australian Standards, Acts and Regulations but can not find any guidance on this matter. Can anyone help?





RE: 2 pole breakers on a single phase NER circuit.
On the assumption that this is allowed in Oz, you must treat the neutral as a 'live' conductor and switch it because it could reasonably be expected to be at a potential greater than earth. On system with a solidly earthed neutral, there is no mutual interaction between circuits which can cause the neutral to be at a potential significantly greater than earth.
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If we learn from our mistakes I'm getting a great education!
RE: 2 pole breakers on a single phase NER circuit.
It is a matter of proper engineering not standards.
Rafiq Bulsara
http://www.srengineersct.com
RE: 2 pole breakers on a single phase NER circuit.
RE: 2 pole breakers on a single phase NER circuit.
The codes that I work (CEC) under mandate solid grounding of the neutral if any line to neutral loads are present. I believe that other posters here work under similar codes.
Bill
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"Why not the best?"
Jimmy Carter