×
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

Transformer testing - Frequency conversion factors / 50Hz to 60Hz
2

Transformer testing - Frequency conversion factors / 50Hz to 60Hz

Transformer testing - Frequency conversion factors / 50Hz to 60Hz

(OP)
50Hz rated transformers are proposed to be tested by the vendor using power supplies rated at 60Hz.
Any advice on the conversion factors to be applied for load loss etc.!!
Thanks in advance.

RE: Transformer testing - Frequency conversion factors / 50Hz to 60Hz

This doesn't sound like a great idea, however if there isn't any other way the conversion factors are as follows:

Load loss -- measure at 60 hz then measure the resistance, using the resistance calculate the I2R losses. Then subtract the I2R losses from the measured loss. The remaining is the eddy and stray loss,however since these were measured @ 60 hz the value must be reduced by (50/60)^2. The sum of the I2R and the corrected eddy loss value will be close to the 50 hz load loss;

Open circuit -- This is more dificult. The best you can do to approximate the 50 hz losses is to test at 83.3% rated voltage. The result will only approximate the 50 hz value.  

RE: Transformer testing - Frequency conversion factors / 50Hz to 60Hz

Raghun -- I made a mistake on the open circuit test. You have to increase the voltage by 20%. This will produce the same flux density as rated voltage at 50 hz.  

RE: Transformer testing - Frequency conversion factors / 50Hz to 60Hz

If a temperature rise test is to be perfomred with  cooling fans or pumps running, the fans will operate 20% faster and provide a lot more cooling air flow.  I do not know of a conversion factor to adjust for that increase.

You could require a 50 Hz fan supply if temperature rise with fans operating is a required test.  Additional cost for a VFD to supply the fan power during the test is not that much.

RE: Transformer testing - Frequency conversion factors / 50Hz to 60Hz

Raghun,There are many  un official conversion factors used  by transformer manufacturers.Corrections will be required for 1) Impedance 2)No-load losses 3) Load losses 4) Excitaion current 5) Sound level 6) Insulation power factor 7) Induced voltage test duration.

Official version you can get from draft IEEE Std PC57.12.90-D10 of 2009-02 Annexure B Guide for testing trfs.You can also see a tutorial at www.transformerscommittee.org by ABB during 2008 fall meeting.
 
Attached is a summary for 60 to 50 HZ conversion as per IEEE paper(Power Delivery Vol 18 No4 2003-10) "Proposed standards for frequecy conversion factors of trf performance parameters"by Dr Girgis etc of ABB  

RE: Transformer testing - Frequency conversion factors / 50Hz to 60Hz

(OP)
Thanks to you all - pie314, rcwilson and prc.

The cooling fan/pump issue is a good point, rcwilson.

Thanks for the references, prc. I could get the ABB paper and I am still trying for the draft copy of the IEEE. Guess the IEEE would be made official soon. It would be one more step in the process of harmonisation between IEEE and IEC, I think.
 

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