×
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.

# Help With Per-Unit Impedance Base conversion for Sample Power PE Exam

## Help With Per-Unit Impedance Base conversion for Sample Power PE Exam

(OP)
Hello,

I was looking at the sample PE exam question below.

When solving the question i decided to use the XFMR Secondary voltage and MVA as my base values.

Which then required the Gen imp to be converted to the XFMR MVA base.

When doing so the first time i followed the process below:

Vbase=230kV, MVA Base=933 MVA

Ibase= MVA Base/ Sqrt(3) * Vbase

Zgen_933MVA= Zgen_834MVA * (kV old/KV_New) * (MVA new/MVA Old) = (0.23)*(22/230)^2 * (933/834)

However, after looking at the solution i see that the voltage conversion is not necessary.

If i remove the voltage conversion ratio then my answer matches the MVAsc from the solution.

Can anyone clarify when the voltage transformation is indeed applicable and touch on why its not applicable in this case?

#### 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.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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!