Lecture 0: Introduction to Engineering Electromagnetics BEF 22903 Lecture 0: Introduction to Engineering Electromagnetics

Course Learning Outcomes After completing this course you will be able to: Interpret vector calculus operators and their application in electromagnetics Use Coulomb’s law to solve electrostatic problems. Use Gauss’ law to calculate electric field density and intensity. Understand electric scalar potential. Explain and calculate capacitance and self inductance of different structures. Calculate energy, forces and pressure as result of static electric fields. Understand properties of Conductors and dielectrics. Explain electromagnetic induction. Explain and understand self and mutual inductance. Use Ampere’s law to solve Magnetic circuits. Explain differences in magnetic field in a vacuum and Magnetic fields in materials. Calculate energy and forces of magnetic circuits.

APPLICATIONS OF ENGINEERING ELECTROMAGNETIC Microwave Oven Electromagnetic radiation that range from approximately 1 ft (30 cm) in length to the thickness of a paper. Microwave oven heat food by causing water molecule to rotate at a frequency of 2.45 GHz.

The water molecules can absorb energy and get to excited vibrational and rotational levels, and that is the basis of your microwave oven.

INDUCTION HEATING The heating of a nominally electrical conducting material by eddy currents induced by a varying electromagnetic field. The principle of the induction heating process is similar to that of a transformer. In the illustration, the inductor coil can be considered the primary winding of a transformer, with the workpiece as a single-turn secondary. When an alternating current flows in the primary coil, secondary currents will be induced in the workpiece. These induced currents are called eddy currents. The current flowing in the workpiece can be considered as the summation of all of the eddy currents.

Induction Heating Systems for the Power Generation Industry Induction heating systems are used primarily for the following tasks within the power industry: Brazing series connections Brazing turbo-generator connections Brazing short-circuit rings Solidifying bar ends Brazing strands / windings Shrink-fitting of end caps Cleaning varnish Post and pre-heating General shrink-fitting Expanding and removing of large bolts

Induction Heating Systems for the Power Generation Industry Fast brazing without the risk of damage to the insulation; the handheld transformer is as easy to use as a normal drill.

Induction Heating Systems for the Power Generation Industry Removing large turbine bolts with a mobile induction heating system.

Principle of induction heating. The power unit, below, generates a magnetic field. When the magnetic field is absorbed by a ferrous material, such as a steel or iron pan, the magnetic energy is converted into heat. The heat is induced directly into cooking utensil, avoiding the need for heat to be conducted through any intervening material, resulting in a more efficient use of energy and a cooler cooking surface

Dielectric Heating Dielectric heating, also known as electronic heating, RF heating, high- frequency heating and diathermy, is the process in which a high-frequency alternating electric field, or radio wave or microwave electromagnetic radiation heats a dielectric material. At higher frequencies, this heating is caused by molecular dipole rotation within the dielectric.

Dielectric Heating A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material as they do in a conductor, but only slightly shift from their average equilibrium positions causing dielectric polarization. Because of dielectric polarization, positive charges are displaced toward the field and negative charges shift in the opposite direction. This creates an internal electric field which reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, but also reorient so that their symmetry axis aligns to the field.

Dielectric Heating A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material as they do in a conductor, but only slightly shift from their average equilibrium positions causing dielectric polarization. Because of dielectric polarization, positive charges are displaced toward the field and negative charges shift in the opposite direction. This creates an internal electric field which reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, but also reorient so that their symmetry axis aligns to the field.

High Frequency Vacuum Drying Kiln This vacuum drying kiln applies high frequency dielectric heating. The vacuum condition makes the moisture soon out, and the high frequency heating penetrates the wood and works only on the water contained in the wood exactly, so the wood can be dried much sooner than conventional heating kiln. What's more, the high frequency power works thoroughly, and can make the water content evenly after dried, thus eliminates the bending or spring of wood after drying. The HF power will also completely kill the bacteria or insect with in the wood. Capacity: 3/6cu meter Power: 30/50kW HF generator Drying time; about 20hours Condition: HF drying/Vacuum

Electrostatic Painting Gun

END