×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Transformer Overload Capacity

Transformer Overload Capacity

Transformer Overload Capacity

(OP)
Could anyone refer me to a source which I can find info on xfrms overload capacity (especially liquid fill) based on their temperature rise capabilities?

I am told that 55deg xfrm overload is different from 65Deg and
55/65 deg transformer.
one is 112% the other one is 133%.
For long time pick up setting of an overcurrent protection  on the secondary side of a transformer.

Thank you

RE: Transformer Overload Capacity

It depends on a lot of things, such as ambient temperature, load cycle, initial loading, type of insulation, size of transformer, method of cooling ie forced or natural, how much life expectancy you want to sacrifice etc. As a first pass have a look for the specification the transformer was built to, or ask the manufacturer. GE Power produce a handy little guide called the Distribution Transformer Manual GET-2485R which has lots of information on overloading transformers. I'm not sure if it's available electronically though.
Regards
Marmite

RE: Transformer Overload Capacity

ANSI/IEEE Std C57.91, IEEE Guide for Loading Mineral-Oil-Immersed Transformers

RE: Transformer Overload Capacity

You can find requirements that will allow you to provide protection up to 250% of the transformer's FLA.

At one time, I had a pamphlet from ABB (I think) regarding their recommendations for protection of their transformers. It showed the short-time overload ratings near that value, but for only several minutes or so. My suggestion is to find out your transformer manufacturer's recommendations.

Unless you have overtemp protection, your overload protection should be much closer to the FLA unless you want to void any manufacturer's warranty or disregard their recommendations.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources