# How to determine the number of turns of the winding?

• Leonid92
In summary, the conversation discusses the calculation of magnetic field strength and winding turns of an electrical steel core using Kirchhoff's second law for a magnetic circuit and the electrical steel magnetization curve. The textbook provides a different answer for the winding turns, leading to a discussion about finding the correct reference book for the electrical steel magnetization curve. The conversation also clarifies that the term "electrical steel" refers to Silicon Steel, which has unique data that must be used for accurate calculations.
Leonid92
Homework Statement
In the core made of electrical steel (Fig. 1), it is required to create a magnetic flux Φ = 4.2*10^(-3) Wb. Determine the number of turns of the winding, if the current is I = 5 A, and the dimensions of the core are specified in millimeters.
Relevant Equations
Φ = B*S
I*w = H*L
1) B = Φ/S = (4.2*10^(-3) Wb)/(2.5*10^(-3) m^2) = 1.68 T
2) Using electrical steel magnetization curve given in the textbook: magnetic field strength H corresponding to magnetic flux density 1.68 T is equal to 6000 A/m.
3) L is a length of the middle magnetic line of the core (Fig. 2).
L = 2*(200 - 50 + 200 - 50) = 600 mm = 0.6 m
4) According to Kirchhoff's second law for a magnetic circuit:
I*w = H*L,
where w is a number of turns of the winding.
Then:
w = (H*L)/I = 720.

Is it right solution?

The problem is that true answer given in the textbook is w = 240.

Could you please advise good reference book where one can find electrical steel magnetization curve? I'd like to check H value in another book.

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Last edited:
If H is given as 6000 A/m then you don't need any B information. No permeability, no B flux - just the dimensions of the core: Hd = NI where d is path distance (Ampere's law).

Leonid92
rude man said:
If H is given as 6000 A/m then you don't need any B information. No permeability, no B flux - just the dimensions of the core: Hd = NI where d is path distance (Ampere's law).

When posting the thread, I made a mistake. Actually, H is not given. One should determine H using calculated B value and electrical steel magnetization curve.

Leonid92 said:
When posting the thread, I made a mistake. Actually, H is not given. One should determine H using calculated B value and electrical steel magnetization curve.
Makes more sense!
So determine B then divide by mu.
You need to use your textbook magnetization data or you'll get the wrong answer. There are many different kinds of steel, even "electrical steel" (never heard that term before), each with its unique data.

Leonid92
rude man said:
"electrical steel" (never heard that term before)
It's a term sometimes used to refer to Silicon Steel, typically as used in transformer laminations.

## 1. What is the purpose of determining the number of turns of the winding?

Determining the number of turns of the winding is important in the design and construction of electrical devices, as it determines the strength of the magnetic field and the amount of current that can be carried.

## 2. How do you calculate the number of turns of the winding?

The number of turns of the winding can be calculated by dividing the length of the wire by the wire diameter and multiplying it by the coil length. This will give you the number of turns per layer. Multiply this number by the number of layers to get the total number of turns.

## 3. What factors affect the number of turns of the winding?

The number of turns of the winding is affected by the desired strength of the magnetic field, the type of wire used, the voltage and current requirements, and the size and shape of the coil.

## 4. How does the number of turns of the winding affect the performance of an electrical device?

The number of turns of the winding directly affects the strength of the magnetic field and the amount of current that can be carried. A higher number of turns will result in a stronger magnetic field and the ability to carry more current, while a lower number of turns will result in a weaker magnetic field and the ability to carry less current.

## 5. Can the number of turns of the winding be altered after construction?

In most cases, the number of turns of the winding cannot be altered after construction. This is because the winding is typically tightly wound and altering it could damage the device. However, in some cases, a few turns can be added or removed to make minor adjustments to the performance of the device.

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