×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# High-tertiary impedance design change from 12% to 26%

## High-tertiary impedance design change from 12% to 26%

(OP)
Can somebody explain what would be the effect of changing the H-Y (high to tertiary) impedance in a 120/160/200 MVA, 260-144/25 kV, three phase  autotransformer, from 12% (required) to 26% (per design). The H-X impedance is 5%.
Thanks for the info.

### RE: High-tertiary impedance design change from 12% to 26%

The question is not clear.Can you explain?What is meant by "required" and "designed"?Also indicate T-X impedance also on both cases.Hope H-Ximpedance remains the same.

### RE: High-tertiary impedance design change from 12% to 26%

(OP)
A corp. requires a 120/160/200 MVA auto Xfr with H-X=5% and H-Y=21% requirements. However our engineering can only comply with the H-X at 5%, and only provide H-Y = 36% impedance instead of 21%. My questions is what can possibly change with our  deviation? Does it matter if the tertiary is buried or if it is loaded? If so, why should that be?

### RE: High-tertiary impedance design change from 12% to 26%

If the tertiary is buried it will not matter at all ,but in a way better as the circulating current in tertiary will be reduced.But if it is aloaded tertiary ,regulation at tertiary terminals  will be higher as the T arm of the circuit will have higher impedance.

#### 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.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!