×
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

Short Circuit calculations with site rated gas turbines

Short Circuit calculations with site rated gas turbines

Short Circuit calculations with site rated gas turbines

(OP)
I am working with a gas turbine gen set and I have some questions regarding Short Circuit calculations and Short Circuit power.

The turbine has a site rating of about 12,5 MW (15,6 MVA) and a ISO rating of about 15 MW (18,5 MVA) power factor of 0.8. The alternator is rated 18,5 MVA.

So when I calculate the SC rating I use the alternator name plate rating of 18,5MVA.

My question is, will you always get maximum SC current independent of the turbine output? Or do I have to have ideal circumstances where the turbine gives the needed mechanical power?

If the current is dependent on the mechanical power from the turbine, can you detail?
 

RE: Short Circuit calculations with site rated gas turbines

A short circuit takes a lot of MVA but little MW.
Power equals current times voltage times power factor.
In the event of a short circuit the voltage may be very low so the power or MW requirements are lowered.
The short circuit current is very reactive so although there are a lot of KVAs, when that is multiplied by the low power factor resulting from the reactive current  the KW or MW demands are lowered.
I would use the alternator rating for short circuit calcs.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Short Circuit calculations with site rated gas turbines

The short circuit behaviour is principally controlled by the transient and sub-transient reactances of the alternator,and are almost completely independent of the prime mover over the duration of the fault.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

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