Transformer Overload protection
Transformer Overload protection
(OP)
In NEC and CEC, transformer overload protection is not mentioned anywhere. If we look at TCC curves, overload zones always seem to have a problem with protection by using Thermal magnetic breakers, even though we follow the CEC or NEC rules to set the settings, especially for low voltage small dry type transformers. I talked to one of engineers in town. He said the tranformer will be protected so long as we set as per CEC. I want to hear your experiences , especially for small dry type transformers.
Thanks.
Thanks.






RE: Transformer Overload protection
RE: Transformer Overload protection
RE: Transformer Overload protection
RE: Transformer Overload protection
RE: Transformer Overload protection
Thermal-magnetic circuit breakers have way too much tolerance in their settings to truly and tightly protect the transformer, coordinate with upstream and downstream devices, meet the NEC (and presumably CEC) requirements, and allow the transformer to be used at full nameplate rating. The consensus standard of care is to meet the NEC sizing requirements.
As the transformers become larger and the protective devices more sophisticated it becomes easier to meet all of the protective objectives.
RE: Transformer Overload protection
As matter of fact, as Davidbeach indicated, thermal-magnetic circuit breakers won't protect small transformers very well. So caution should be taken to select thermal-magnetic cicuit breakers for the protection purposes of the transformers. There are always some cases where the equipment is not fully protected, so long as we abide by the codes.
RE: Transformer Overload protection
P.S. Such protection goes for all voltage ranges, and from type of transformer you can have more protections recommended from manufacturer, like ventilators that are going on and off depending of the temperature, water cooling for oil cooling, Buchholz relay for gas detection .... There are many aspects, try using google for them.
(oil transformer protection filetype:pdf)
RE: Transformer Overload protection
ht
This one explains usage of circuit breakers (yes they are necessary as cheap way of protecting network when everything else fails)
http://www.sandc.com/edocs_pdfs/EDOC_027579.pdf
and this one is I believe all most of us will ever need for such application.
http://www.basler.com/downloads/transfguide.pdf