Calculating flux density in an air gap

• escape_velocity
In summary, the conversation discusses the calculation of flux density in an air gap of an electromagnet. The individual is using a C core with an air gap and is confused about how to calculate the flux density for 50Hz AC instead of DC. They mention the parameters of their C core and the needed flux density of 1 Tesla in the air gap. The expert suggests calculating the DC current first and then using the AC impedance and needed current to calculate the AC voltage.

escape_velocity

I am trying to calculate the flux density of an air gap in an electromagnet.
I am following this page that calculates the flux density in a C core with an air gap.

My confusion is that I am using 50Hz AC instead of DC I have control over the voltage amplitude since I would be using a variac to do my initial tests.

Would the calculations differ for AC, my guess is that it would be different since the AC impedance of the coil would come into play and that would change the MMF(magneto-motive force) value.

I have a C core of Electrical steel (laminated) with the following parameters
Permeabity of core = 5.0×10−3 H/m
Cross section Area = 1cm2
Magnetic Path Length = 19cm
Air Gap length = 1cm
Flux Density needed in air gap = 1Tesla

Would appreciate your thoughts on how to go about doing this calculation.

escape_velocity said:
My confusion is that I am using 50Hz AC instead of DC
Well, if you use a sinusoidal AC current, you will get a sinusoidal flux. The flux density is proportional to the current.

So is the needed flux density ( 1T ) the peak value, the RMS value or . . . ?

I suggest that you calculate the DC current at first. You should find the result as: amps⋅windings. The AC impedance depends on the number of windings ( and on the resistance of the windings ). Knowing the impedance and the needed current, you can calculate the AC voltage needed.

1. What is flux density in an air gap?

Flux density in an air gap refers to the measure of the strength of a magnetic field within a gap or space between two magnetic poles. It is typically measured in units of Tesla (T) or Gauss (G).

2. How do you calculate flux density in an air gap?

The formula for calculating flux density in an air gap is B = μ0 * (N * I) / (l + δ), where B is the flux density, μ0 is the permeability of free space, N is the number of turns in the coil, I is the current flowing through the coil, l is the length of the air gap, and δ is the thickness of the air gap.

3. What factors affect the flux density in an air gap?

The flux density in an air gap is affected by the number of turns in the coil, the current flowing through the coil, the length and thickness of the air gap, and the permeability of the materials surrounding the air gap. Additionally, the direction and shape of the magnetic field also play a role in determining the flux density.

4. Why is calculating flux density in an air gap important?

Calculating flux density in an air gap is important in understanding the strength and behavior of magnetic fields. It is also crucial in designing and optimizing magnetic circuits for various applications, such as motors, generators, and transformers.

5. Can flux density in an air gap be manipulated?

Yes, flux density in an air gap can be manipulated by changing the factors that affect it, such as the number of turns in the coil, the current flowing through the coil, and the length and thickness of the air gap. By adjusting these parameters, the strength and direction of the magnetic field can be altered to suit specific needs and applications.