Harmonic Distortion Abbreviation

[Jmadamek]

I have an output from Dranview showing harmonic distortion in a three-phase system. the system consists of motors fed from single phase drives, protected by breakers, and the breakers have been 'randomly' tripping.

My term in questions is VTHDRss. There is a voltage vs time graph showing the Phase <A, B, C> Harmonic Timeplot, and the dots/lines that are plotted are labeled with that term. I'm fairly certain that the 'VTHD' part refers to Voltage Total Harmonic Distortion, but am unsure what the Rss stands for. Google only brought up a pdf in a foreign language( .no tag, Norway?) which is more or less an example of the output.

link to said pdf

http://www.bio.uib.no/internesider/Ombygg/Forprosjekt HIB 3 og 4 etg.pdf

Page 46, top graph on the page.

The only difference in the graphs seems to be a set up feature in the program, since my graph has only dots(compared to the example which has lines). Further, where the two voltage sags occurred in the time frame, there are vertical lines on that graph. I don't really know how to interpret the graph(since I don't know what VTHDRss is), but I'm hoping this term will clear it up a bit.

Thank you.

 

[Skogsgurra]

The Norwegians sometimes use the abbreviation Rss (middel) for RMS. It is English, actually. Root sum squared with (middle) meaning "mean". Same thing as Root Mean Squared or RMS.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Jmadamek]

Interesting. Seems odd that they wouldn't just use RMS for the English version to avoid confusion.

 

[Skogsgurra]

Well - that's how it is.

What else would you suggest?

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ozmosis]

I came across rss a few years ago and had the same thoughts, (even though I'm an Englishman!)but I was wondering why the capital "R" and lower case ss at the time-an apparant emphasis on the word Root.
Regarding your comment about the single phase(input) VSD tripping your breakers. This will likely be the 3rd harmonic and is often solved by introducing a line reactor to the drive.

 

[ijl]

THDR = the total harmonic distortion of the waveform as % of input Vrms (or Irms).
THDF = the same, but as % of fundamental.

But ss? My guess = steady state