B-H Curve and Hysteresis Loop Determination

Introduction

The B-H curve and hysteresis loop determination are important concepts in electrical measurements and instruments. They provide valuable information about magnetic materials and help in designing efficient electrical devices. This article will explain the fundamentals of the B-H curve and hysteresis loop determination, as well as the measurement techniques and real-world applications.

B-H Curve

The B-H curve, also known as the magnetization curve, is a graphical representation of the relationship between the magnetic field strength (H) and the magnetic flux density (B) of a material. It is used to characterize the magnetic properties of materials.

The B-H curve exhibits several characteristics:

1. Saturation region: At high values of magnetic field strength, the magnetic flux density reaches a maximum value and does not increase further.

2. Linear region: In the linear region, the relationship between H and B is linear, indicating a proportional relationship between the applied magnetic field and the resulting magnetic flux density.

3. Knee point: The knee point is the point on the B-H curve where the relationship between H and B changes from linear to nonlinear.

4. Hysteresis loop: The hysteresis loop is the closed loop formed by the B-H curve when the magnetic field strength is varied from positive to negative and then back to positive values.

Hysteresis Loop Determination

The hysteresis loop is a characteristic of magnetic materials that shows the relationship between the magnetic field strength and the magnetic flux density during a complete cycle of magnetization and demagnetization. It provides information about the energy losses and magnetic properties of materials.

There are several measurement techniques for determining the hysteresis loop, including the Lloyd Fischer square method and the Epstein frame method. In this article, we will focus on the Lloyd Fischer square method.

The Lloyd Fischer square method involves the following steps:

1. Preparation of the sample: The sample material is cut into a square shape and prepared for testing.

2. Placing the sample in the Lloyd Fischer square: The sample is placed in the Lloyd Fischer square, which consists of two coils wound on a square-shaped iron core.

3. Applying magnetic field and measuring the magnetic flux density: A current is passed through the coils to generate a magnetic field, and the magnetic flux density is measured using a magnetic field sensor.

4. Plotting the hysteresis loop: The magnetic field strength and magnetic flux density values are plotted to create the hysteresis loop.

The hysteresis loop determination has various real-world applications, including the measurement of power loss in sheet metal and the characterization of magnetic materials.

Advantages and Disadvantages

The B-H curve and hysteresis loop determination have several advantages and disadvantages.

Advantages:

1. Provides valuable information about magnetic materials: The B-H curve and hysteresis loop determination help in understanding the magnetic properties of materials, such as their magnetic saturation, coercivity, and remanence.

2. Helps in designing efficient electrical devices: The knowledge gained from the B-H curve and hysteresis loop determination can be used to design electrical devices with optimal magnetic properties.

Disadvantages:

1. Requires specialized equipment and techniques: The measurement of the B-H curve and hysteresis loop determination requires specialized equipment, such as the Lloyd Fischer square, and techniques that may not be readily available.

2. Time-consuming process: The measurement process for determining the B-H curve and hysteresis loop can be time-consuming, especially when multiple samples need to be tested.

Conclusion

In conclusion, the B-H curve and hysteresis loop determination are important concepts in electrical measurements and instruments. They provide valuable information about magnetic materials and help in designing efficient electrical devices. The measurement techniques, such as the Lloyd Fischer square method, allow for the determination of the hysteresis loop and its real-world applications, including the measurement of power loss in sheet metal and the characterization of magnetic materials.

Summary

The B-H curve and hysteresis loop determination are important concepts in electrical measurements and instruments. The B-H curve is a graphical representation of the relationship between the magnetic field strength and the magnetic flux density of a material. It exhibits characteristics such as saturation, linearity, knee point, and hysteresis loop. The hysteresis loop is a characteristic of magnetic materials that shows the relationship between the magnetic field strength and the magnetic flux density during a complete cycle of magnetization and demagnetization. The Lloyd Fischer square method is a measurement technique for determining the hysteresis loop. The B-H curve and hysteresis loop determination have advantages in providing information about magnetic materials and helping in designing efficient electrical devices, but they also have disadvantages in requiring specialized equipment and techniques and being a time-consuming process.

Analogy

Imagine a roller coaster ride that goes up and down hills. The B-H curve is like a graph that shows the height of the roller coaster at different points along the track. The hysteresis loop is like the complete cycle of the roller coaster going up and down the hills. By measuring the B-H curve and hysteresis loop, we can understand the magnetic properties of materials, just like we can understand the characteristics of the roller coaster by looking at its height and the complete cycle of its ride.