Calculating Voltage Drop in Transformers

[binaryblade]

I need help find a good page which talks about the physics of a tranformer. I know all about the b fields and the flux and the ratio of the windings but what I really need is the practical formulea and methods for example calculating the voltage drop on the primary if the secondary has aresistance of so much and there is a resistor in series with the primary. I could experiment with different variations and figure it out but it would be a lot safer and quicker to find a reference for this material. I really would appreaciate help in this matter.

 

[mmwave]

I've never seen a specific reference on transformers. I learned the stuff you're asking about in RF design classes. Maybe this will help:

V2 = N2/N1 * V1
I2 = N1/N2 * I1
P1 = P2

Use an ideal transformer as a circuit element & put the resistances in as circuit elements. For example if the secondary has a resistor of R2 ohms & you look into the primary the above relations will show you see a resistance of

Rin = (N1/N2)^2 * R2

This Rin would be added to any resistance in the primary winding to make a practical dc cicruit model. For ac, you apply the same idea to the capacitance of the windings using Zc = 1/(2pifc). It works well for frequencies below the self-resonant freq. of the transformer.

I think this is covered in a wonderful book by Tom Lee called
"CMOS RFIC Design".

mmwave ( writing without his EE211 notes)

 

[ravenprp]

Calculating voltage drop in transformers involves understanding the basic principles of electromagnetic induction and the relationship between voltage, current, and resistance. One useful resource for learning about the physics of transformers is the website of the Institute of Electrical and Electronics Engineers (IEEE). They have a section dedicated to transformer basics, which includes information on transformer construction, operation, and calculations.

To calculate voltage drop in a transformer, you will need to use the formula V = I x R, where V is the voltage drop, I is the current, and R is the resistance. The key is to determine the values for each of these variables. You can use the number of turns in the primary and secondary windings, the transformer's turns ratio, and the primary and secondary resistances to calculate the voltage drop.

Another important factor to consider is the transformer's impedance. This is the combined effect of the transformer's resistance, inductance, and capacitance. It can be calculated using the formula Z = √(R² + (Xl - Xc)²), where R is the resistance, Xl is the inductive reactance, and Xc is the capacitive reactance. Once you have calculated the impedance, you can use it to determine the voltage drop in the transformer.

There are also online resources and software programs available that can help you calculate voltage drop in transformers. These tools can save you time and provide more accurate results. However, it is still important to have a good understanding of the underlying principles and formulas so that you can verify the results and make adjustments if necessary.

In conclusion, to calculate voltage drop in transformers, you will need to use formulas and methods that take into account the transformer's turns ratio, primary and secondary resistances, and impedance. It is important to have a good understanding of the physics behind transformers and to use reliable resources to ensure accurate calculations. The IEEE website is a great place to start, and there are also other resources available online that can assist you in your calculations.