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-   -   Question about phase in an inductor (http://www.diyaudio.com/forums/everything-else/89394-question-about-phase-inductor.html)

percy 31st October 2006 06:21 PM

Question about phase in an inductor
 
Below is an impedance chart of a ~1.9mh inductor. Blue is reactance, Yellow is phase. This was measured using Speaker Workshop (passive component measurement feature).

http://i94.photobucket.com/albums/l1...nductorDCR.jpg

Typically when I measure a capacitor or a resistor I get a dead straight line for phase (yellow) at 0 for a resistor and -90 for a capacitor. But when I measure an inductor the phase gets skewed like shown in the chart. It starts shifting towards 0 in the low frequency range. Why is that ? My guess is that it could be because of the DCR of the inductor.

I get similar results when I measure high value (1000uf+) capacitors. The phase starts shifting towards 0 in the high frequency range. Again, ESR ?



What do you guys think of an explanation for this ?

soongsc 1st November 2006 09:33 AM

How does your measurement.calib look?

sreten 1st November 2006 11:58 AM

Hi,

Think about it. What would a speaker inductor that could
maintain 90 degrees phase shift at 10 Hz look like ?
How low would its DCR need to be ? How big would the
core need to be for the current from your drive voltage ?

:)/sreten.

percy 1st November 2006 03:51 PM

Quote:

Originally posted by soongsc
How does your measurement.calib look?
flat

Quote:

Originally posted by sreten
Hi,

Think about it. What would a speaker inductor that could
maintain 90 degrees phase shift at 10 Hz look like ?
How low would its DCR need to be ? How big would the
core need to be for the current from your drive voltage ?

:)/sreten.

so it IS about dcr/esr, right ?

Tweeker 2nd November 2006 08:19 AM

ESR in the main and interwinding capacitance?

Quote:

I get similar results when I measure high value (1000uf+) capacitors. The phase starts shifting towards 0 in the high frequency range. Again, ESR ?
This is in part an effect of the capacitors ESL. Special measures must be taken for a capacitor to be effective at high frequencies.


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