Question about phase in an inductor

[percy]

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).



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]

How does your measurement.calib look?

[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.

[percy]

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

flat

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]

ESR in the main and interwinding capacitance?

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.