electric 2.3 - INDUCTORS AND INDUCTANCE.pp

Inductance

A property of an electrical component measured in Henrys (H), representing the ability to store energy in a magnetic field when electric current flows.

Magnetomotive Force (mmf)

The magnetic force that drives the magnetic flux in a circuit, calculated as the product of the number of turns and current (N.i).

Reluctance

The opposition to the magnetic flux in a magnetic circuit, analogous to resistance in electrical circuits.

Faraday’s Law of Induction

States that the induced voltage (or emf) in a coil is proportional to the rate of change of magnetic flux linkage through the coil.

Energy Storage in Inductors

Energy is stored in the magnetic field produced by the current flowing in the inductor, as opposed to capacitors which store energy in an electric field.

Ideal Inductor

An inductor that possesses no resistance and is designed to have useful inductance.

Saturation in Inductors

Occurs when the magnetic flux density in the core material exceeds a certain level, leading to diminished inductance.

Hysteresis Losses

Energy losses in a magnetic core due to the lag between changes in magnetizing force and the magnetization of the core.

L-R Series Circuit

A circuit containing both an inductor (L) and a resistor (R), often used to study the transient response to changes in voltage.

Weber (Wb)

The unit of magnetic flux, defined as one volt-second.

Henry (H)

The unit of inductance, defined as the inductance of a circuit in which a change in current of one ampere induces a voltage of one volt.

Eddy Currents

Looped currents induced in conductors by a changing magnetic field, which can lead to energy losses.

Flemings Left-Hand Rule

• thumb = direction of force (motion),

• first finger = direction of the magnetic field (B),

• second finger = direction of the induced current (I).

Faraday's Right-Hand Rule

• thumb = direction of the induced current

• fingers = direction of the magnetic field (B)

Iron Losses

• Occur when iron is subjected to changing magnetic fluxes.

• Include ‘hysteresis’ and ‘eddy-current’ losses.

• Iron is often laminated to limit eddy current losses.

• High grade ‘electrical steels’ are used to mitigate losses by:

  • Having high resistivity (ρ) to limit eddy currents.

  • Undergoing special heat treatment and processing to minimize hysteresis losses.

  • Achieving high saturation flux density (Bsat).

how to reduce energy losses in iron

• laminated steel to curb and reduce eddy currents size.

• using materials with high resistivity.

• applying specialized treatments to lessen hysteresis losses.