# Magnetic equivalent circuit question

• theone
In summary, the student is confused about the dimensions of the circuit, and also about what dimensions to use for the cross section ##A_c##. They are also trying to find the reluctance's for the circuit.
theone

## Homework Statement

The question is to draw a magnetic equivalent circuit for this
http://postimg.org/image/kek5fgr9z/

## Homework Equations

The reluctance is given by
##R=\frac{l}{μ_oμ_rA_c}##

## The Attempt at a Solution

I am confused about the dimensions of the circuit, and also about what dimensions to use for the cross section ##A_c##

For example, is the reluctance R1 given by

##R_1=\frac{\frac{60}{1000}}{μ_0 1500 (\frac{20}{1000} \frac{20}{1000})}##

#### Attachments

• IMG_20150522_211737145.jpg
23 KB · Views: 325
theone said:
The question is to draw a magnetic equivalent circuit for this

Draw an electric equivalent, substituting the (magnetic) bars by (7) resistances. N1 can be substituted by a current source, N2 by an amp-meter.

Hesch said:
Draw an electric equivalent, substituting the (magnetic) bars by (7) resistances. N1 can be substituted by a current source, N2 by an amp-meter.

but I did that in the attachment. I wanted to check if the dimensions I'm using for ##A_c## is correct

Sorry, I didn't see the attached.

Yes, Ac = 20 * 20 mm2.

What are these ±O symbols meant to be? And why are there two? Are two currents induced in the "transformer" at the same time?

What are these ±O symbols meant to be? And why are there two? Are two currents induced in the "transformer" at the same time?
the mmf from the wounded coil. I'm not sure what the correct symbol is
Shouldn't there be two? ##N_1i_1## on the left and ##N_2i_2## on the right

theone said:
the mmf from the wounded coil. I'm not sure what the correct symbol is
Shouldn't there be two? N1i1N_1i_1 on the left and N2i2N_2i_2 on the right

I don't know anything about american symbols ( I'm from Denmark ), but you must have different symbols for a current source/a voltage source. As suggested in #2, I'd use a current source because of the analogy between electrical current and magnetic flux.

I don't know if there must be one or two current sources, for example: Is N2 loaded/current supplied? I just know:
theone said:
The question is to draw a magnetic equivalent circuit for this

Hesch said:
I don't know anything about american symbols ( I'm from Denmark ), but you must have different symbols for a current source/a voltage source. As suggested in #2, I'd use a current source because of the analogy between electrical current and magnetic flux.

I don't know if there must be one or two current sources, for example: Is N2 loaded/current supplied? I just know:

I forgot to mention that in addition to drawing a magnetic equivalent, the question also asked to find all the reluctance's.

On my diagram there are 4 reluctance's. But the solution only lists three reluctance's : 0.212, 0.292, 0.159 MA/m.

The 0.159 MA/m I can get as ##R_4##,

##R_4=\frac{\frac{60}{1000}}{μ_0 1500 (\frac{10}{1000} \frac{20}{1000})} = 0.159 MA/m##

But I don't know how they got the other two.

I guess that they have reduced the circuit into 3 reluctances:

a) R1+R2+R2 ( in series)
b) R1+R3+R3
c) R4

theone
Hesch said:
I guess that they have reduced the circuit into 3 reluctances:

a) R1+R2+R2 ( in series)
b) R1+R3+R3
c) R4

thanks, I got it now

## 1. What is a magnetic equivalent circuit?

A magnetic equivalent circuit is a simplified representation of a magnetic system that allows for the analysis of magnetic properties and behaviors. It consists of a series of magnetic elements, such as inductors and transformers, connected by magnetic paths to model the magnetic circuit.

## 2. How does a magnetic equivalent circuit differ from an electrical equivalent circuit?

A magnetic equivalent circuit is similar to an electrical equivalent circuit in that they both represent a system using simplified elements. However, a magnetic equivalent circuit takes into account the magnetic properties and behaviors of the system, while an electrical equivalent circuit focuses on the electrical properties.

## 3. What are the advantages of using a magnetic equivalent circuit?

Using a magnetic equivalent circuit can provide a better understanding of the magnetic system and its behavior. It allows for easier analysis and calculation of magnetic properties, such as inductance and magnetic flux. It also simplifies the design process for magnetic systems, as it can help identify potential issues and optimize the system for better performance.

## 4. What factors should be considered when constructing a magnetic equivalent circuit?

When constructing a magnetic equivalent circuit, factors such as the geometry of the magnetic system, the magnetic materials used, and the frequency of the magnetic field should be considered. These factors can affect the magnetic properties and behaviors of the system, and thus, should be accurately represented in the circuit model.

## 5. Are there any limitations to using a magnetic equivalent circuit?

While a magnetic equivalent circuit can be a useful tool for analyzing and designing magnetic systems, it is a simplified representation and may not accurately capture all the complexities of the system. It is important to carefully consider the assumptions and limitations of the circuit model and validate the results with experimental data.

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