Module 3: Electrical Fundamentals - SEM-II Flashcards

Vocabulary practice cards covering magnetism, inductance, DC/AC motors and generators, transformers, and filters based on the Module-3 lecture notes.

Magnetism

The property of an object to attract certain metallic substances.

Magnetic Field

A field that always exists between the poles of a magnet.

Saturation

The point reached when a magnetizing force is applied to magnetic material and no more lines of force can be induced or introduced.

Permeability

The property of materials that allows magnetic lines of force to pass through them; high permeability indicates a material easily passes magnetic flux.

Reluctance

A measure of opposition to magnetic lines of force, which can be compared to the resistance of an electrical circuit.

Retentivity

The magnetic flux that remains in a material when the magnetizing force is reduced to zero.

Lodestone

A hard black material that is a natural magnet.

Inductive Reactance ($X_L$)

The opposition offered by a coil to the flow of alternating current, measured in Ohms ($\Omega$); calculated as $X_L = 2\pi fL$.

Inductance

The primary property of a coil to oppose any change in current.

RL Time Constant

The time required for current in an inductor to change from one value to another, expressed as $T = L/R$.

HC Oersted

The individual who discovered the phenomenon of magnetic effects of electric current.

Pig Tails

Flexible braided copper conductors that provide contact between brushes and the external circuit.

Synchronous Speed

The speed of the rotating magnetic field in an AC motor.

Commutator

A device that changes alternating current produced in the armature of a generator into direct current as it is taken from the armature.

GCU (Generator Control Unit)

A device used to control functions related to regulation, sensing, and protection of the DC generating system.

Split Phase Motor

A motor with starting windings $90^{\circ}$ from the main or running winding that allows for self-starting.

Frequency

The number of cycles of alternating current per second, calculated as $f = \frac{P \times \text{RPM}}{120}$.

RMS Value

The effective value of alternating current, equal to $0.707$ times the maximum value.

Crest Factor

The ratio of the maximum value to the RMS value.

Power Factor

The ratio of true power to apparent power, serving as an indication of the efficiency of an electric unit.

Impedance ($Z$)

The total opposition to current flow in an AC circuit, representing the vector sum of resistance and reactance: $Z = \sqrt{R^2 + (X_L - X_C)^2}$.

Resonance

A state in an AC circuit where inductive reactance ($X_L$) and capacitive reactance ($X_C$) are equal and opposite, leaving only ohmic resistance to oppose current.

Hysteresis Losses

Electrical energy required to magnetize and demagnetize the core of a transformer or motor.

Mutual Induction

The principle on which a transformer works to transfer electrical energy between circuits.

Electronic Filters

Circuits that perform signal processing to remove unwanted frequency components or enhance wanted ones.

Static Inverter

A solid-state device used to convert DC power to AC power, featuring high efficiency and fast response to load changes.

Slip

The difference between the rotating field speed and the rotor speed in an induction motor.