Mutual Inductance dot convention?

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Discussion Overview

The discussion revolves around the dot convention in mutual inductance, focusing on how it affects voltage sources in circuit analysis. Participants explore the implications of the dot convention in the context of a specific circuit and its equivalent representation, including the application of Kirchhoff's Voltage Law (KVL).

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on the dot convention and its application in drawing equivalent circuits, specifically regarding voltage sources related to mutual inductance.
  • Another participant explains that if current enters the dotted terminal of one coil, a positive voltage is induced at the dotted terminal of the second coil, while a negative voltage is induced if current leaves the terminal.
  • A participant proposes a KVL equation based on the dot convention and questions the sign of a voltage in a referenced book, suggesting it should be positive if current enters the dot on L1.
  • Some participants assert that since currents in both coils leave the dotted terminals, the voltage sources should have opposite polarities.
  • There is a discussion about the implications of the dot convention on the signs of induced voltages and how they relate to the KVL equation.
  • One participant expresses gratitude for the explanations received, indicating a clearer understanding of the concept.
  • A later post mentions the use of PSpice for simulating coupled inductances.
  • Another participant seeks further clarification on how the dot convention affects the mutual inductance between coils.

Areas of Agreement / Disagreement

Participants express differing views on the signs of voltages induced by the dot convention, leading to some unresolved questions about the correct application of KVL in this context. Overall, there is no consensus on all aspects of the discussion.

Contextual Notes

Some assumptions about the circuit configuration and the definitions of terms related to mutual inductance may not be fully articulated, leading to potential misunderstandings. The discussion also reflects varying interpretations of the dot convention's implications.

jean28
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Could anyone give me a link that explains or simply explain to me how the dot convention on the mutual inductance works? For example, I'm trying to draw an equivalent circuit that converts the dots into voltage sources of this circuit:

http://i1226.photobucket.com/albums/ee410/jean28x/CircuitMutual.jpg

But I can't seem to figure it out completely. I think a voltage source can be put between I1 and I2 that delivers j2 * I2 volts and another one can be put after the j8 inductor that delivers j2 (I1 - I2) volts but I am not sure.

Thanks a lot!
 
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If current enters dotted terminal of one coil then positive voltage is induced at dotted terminal of the second coil. If current leaves it then induced voltage is negative.
 
1) Currents in both coils leave dotted terminals so voltage sources should have opposite polarization
2) Current enters the dot on L1 so "+" terminal of voltage source is on dotted terminal of L2 hence that voltage is negative
 
Last edited:
szynkasz said:
1) Currents in both coils leave dotted terminals so voltage sources should have opposite polarization
2) Current enters the dot on L1 so "+" terminal of voltage source is on dotted terminal of L2 hence that voltage is negative

Ok i finally got it now. You have no idea how grateful I am for this. Too bad I learned it too late but hopefully I'll be able to apply it well for my next test.

Now, if I could only figure out how to simulate the circuit in the first picture in PSPice or MATLAB...
 
PSpice uses K part for coupled inductances.
 
Thank you very much for your explanation.

Somehow it conveyed the concept better than any textbook.

Thank you!
 
Effective inductance dot convention

So just to make sure... if the current enters the coil at the dotted terminal..how exactly does that effect the other coil and it's dot regarding the mutual inductance...?
 

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