# measuring inductor

Discussion in 'General Electronics Chat' started by TAKYMOUNIR, Jul 5, 2012.

1. ### TAKYMOUNIR Thread Starter Active Member

Jun 23, 2008
351
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when we measure two inductor has the same number of turnfor example if the inductor is250 mh so the equivalent of connecting 2 inductor in parallel will be also 250 mh but if connected in parallel but out of phase it will measure like short circuits ( a few micro henry) my question is when we connect on inductor 20 turn(160 mh) in phase (in parallel) with one 25 turn(250 mh) what is the equivalent inductance in this case and what the equivalent inductance if they connected out of phase in parallel
thanks

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2. ### MrChips Moderator

Oct 2, 2009
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Inductances sum in the same way you sum resistances.

The phase of the inductors have no effect assuming that they are independent (i.e. the flux from one does not interfere with the other).

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3. ### The Electrician AAC Fanatic!

Oct 9, 2007
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The only way two inductors of 250 mH connected in parallel can give a resultant inductance of 250 mH is if the two coils are wound on the same core. Is that the case for your problem?

If this is the case, why didn't you say so? It makes a great deal of difference.

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4. ### TAKYMOUNIR Thread Starter Active Member

Jun 23, 2008
351
1
yes they wound on the same core

5. ### TAKYMOUNIR Thread Starter Active Member

Jun 23, 2008
351
1
the two inductors wound on the same core

6. ### The Electrician AAC Fanatic!

Oct 9, 2007
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7. ### TAKYMOUNIR Thread Starter Active Member

Jun 23, 2008
351
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please this formula for calculating inductance in both case (parallel inphase and out phase) so what is the inductance of(160mh(20turn) and 250mh(25turn)) connected parallel inphase and also for connecting parallel outphase and in both case they ara wounded on the same core

8. ### The Electrician AAC Fanatic!

Oct 9, 2007
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The formula is in the reference I gave you.

You must know the mutual inductance (M) between the two coils to calculate the effective inductance of the two coils in parallel. Do you know or can you measure M?

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9. ### TAKYMOUNIR Thread Starter Active Member

Jun 23, 2008
351
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how can i measure mutual inductance in both case connected in parallel inpase and outphase
thanks

10. ### The Electrician AAC Fanatic!

Oct 9, 2007
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You would use a suitable instrument, for example, an LCR meter: