×
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

Measuring Power Factor - Errors???

Measuring Power Factor - Errors???

Measuring Power Factor - Errors???

(OP)
In the process of measuring power factor, I wish to use a C.T. and a P.T., how do I determine the errors that these devices will introduce to the signals I am trying to measure?

What are accepted methods of measuring PF? How do I minimise these errors?

Nigel.

RE: Measuring Power Factor - Errors???

Suggestion:
CTs and PTs have their errors determined by the standards to which manufacturers manufacture them. Standards vary.
PF can be measured by a voltmeter, ammeter and wattmeter.
The worst case PF Error is given by the additions or meter errors in terms of meter accuracies. The error may be minimized by more accurate meters.

RE: Measuring Power Factor - Errors???

Would suggest that when using PT and CT that you keep the burden on the PT & CT as light as possible. You may want to look at the calibration curve for these devices. You will get a very good idea of how much and in what direction the errors will go.
If harmonics are in the circuit you may want to use digital filtering once you have collected the raw data.

RE: Measuring Power Factor - Errors???

Suggestion:
Total Power Factor will include effects of harmonics
Displacement Power Factor will include fundamental waveforms of voltage, current, and power only.

RE: Measuring Power Factor - Errors???


ANSI C12.11-compliant instrument transformers are shipped with individual ratio- and angle-correction records.  Some multifunction meters allow for software modification using correction/compensation values, and an assortment of power-factor displays.  
  

RE: Measuring Power Factor - Errors???

(OP)
Regarding Standards, ie ANSI and IEEE, where do i go to find the documents? Are there any links to sites that have these available, or must they be ordered and purchased?

Thankyou all for your quick and helpful responses!

Regards, nigel.

RE: Measuring Power Factor - Errors???


A fair number of electrical standards are available for purchase as PDFs with online ordering features.   It takes a little getting used to, but there’s standards.ieee.org, shop.ieee.org, ansi.org and a vendor global.ihs.com
    
Typing  ANSI C12.11 description  in to a google search field will return a description of the standard.
  

RE: Measuring Power Factor - Errors???

How about connecting a load of known power factor, i.e. a resistive load and see what readings you get. You could also make a measurement with a purely capacitive load. Pure inductance is dificult to achieve.
You need to use a supply that is very clean and undistorted for the capacitive measurement.

Best regards,

Mark Empson
http://www.lmphotonics.com

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