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Inductance measurement- Which is better?

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vinogunasekaran

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Hi,

I have come across unknown inductance measurement by
(i) connecting a resistance in series with the inductance, thereby measuring the time constant, from which the inductance value is calculated

(ii) By using a resonant circuit, from the resonant frequency.

Which way of measuring gives a better accuracy of inductance measurement? and why?
 

Already answered in may previous post

1) Direct measurement with help of LCR Meter/ LC meter
2) Direct measurement with DC Current applied in LCR Meter
3) Indirect method : Apply AC voltage to inductor and measure voltage and current then calculate the inductance from impedance, Impedance = V/i
Z = √ [R^2 + (XL-Xc)^2]
 

In my opinion for measuring inductance better method is
(i) connecting a resistance in series with the inductance, thereby measuring the time constant, from which the inductance value is calculated.....because in this method Connect the inductor coil in series with a resistor whose resistance value is known and then finding the frequency of the current is also easy in this method...
 

hi i asked which is better of the two (i) LR time constant (ii) resonant frequency, in terms of accuracy.

- - - Updated - - -

hi smijesh, i asked which is better of the two (i) LR time constant (ii) resonant frequency, in terms of accuracy.
 

It depends on the size and type of inductor.

If its small with very low inductance, the resonant frequency method is best.
Resonance could be at tens or even hundred of Mhz in extreme cases.

If its some huge iron cored monster choke, that may have to carry substantial dc current, the inductance is going to change with dc bias. Especially where it gets up to near magnetic saturation. You will need to measure it with dc flowing through it, and the resonance method is not appropriate.

The answer is, you need to have several different practical methods available to measure different kinds of inductor. There is no single "best" method for every situation that may arise.
 
In different words, Practically, Inductance can vary with frequency (due to parasitic capacitance), temperature of core (permeability varies) and current (affects the losses).
So Inductance measurement should be done at conditions in which it is going to be used.

if application of an inductor is 10KHz, 100mA but inductance measurement is done at DC at 1mA ...
This may not be a useful value.
 

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