×
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

Autotranformers on 13.8kV or 15kV systems

Autotranformers on 13.8kV or 15kV systems

Autotranformers on 13.8kV or 15kV systems

(OP)
We have (2)10MVA 15kV-4160V transformers that feed essential load of about 9 MVA. There is an independent 13.8kV system on the site.  

To increase the reliability, it would be to our advantage replace one of the 15kV feeders and feed from the 13.8kV system.

Instead of buying a new transformer, I wonder if it is feasible to get an autotranformer that could bump the voltage from 13.8kV to 15kV and re-use one of the existing tranformers? Any problems?
 

RE: Autotranformers on 13.8kV or 15kV systems

An autotransformer would definitely work.  

If the existing transformers have taps, which they probably do, you might want to look at that option as well.  

A standard transformer would have two 2.5% taps above and below the nominal voltage.  95% of 15 kV is 14.25 kV, is only 103.3% of 13.8 kV.  So this might work for you, especially in an emergency condition.   

RE: Autotranformers on 13.8kV or 15kV systems

I should have explained it the other way - on the 14.25 kV tap connected to a 13.8 kV source, your voltage would be about 97% of nominal on the 4160 V side.   

RE: Autotranformers on 13.8kV or 15kV systems

You could get a set of voltage regulators since they handle a voltage range of +/- 10%.  A 10 MVA transformer would be matched up with a 1 MVA three-phase regulator or 3 - 333 kVA single-phase regulators.  A voltage regulator is an autotransformer with a tap changer.

You'd have to see if the available short circuit current exceeds the capability of the voltage regulator.  Other than that, a 333 kVA regulator is a standard rating.

Otherwise, the straight autotransformer would work.

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