Transformer and Choke Coil Review Flashcards

Vocabulary flashcards covering the definitions, principles, construction, and formulas of transformers and choke coils based on the lecture notes.

Transformer

A static electrical device that changes low alternating voltage at high current to high or low alternating voltage at low or high current respectively without loss of energy.

Laminated Soft Iron Core

The core of a static transformer that concentrates magnetic flux and is laminated to reduce eddy currents and heat loss.

Step-Up Transformer

A transformer in which the secondary turns are greater than primary turns ($N_2 > N_1$), resulting in increased voltage and decreased current.

Step-Down Transformer

A transformer in which the secondary turns are less than primary turns ($N_2 < N_1$), resulting in decreased voltage and increased current.

Even Ratio Transformer

A transformer in which the secondary turns equal the primary turns ($N_2 = N_1$), resulting in the same voltage and current.

Power Conservation Principle

The principle stating that electrical power in both primary and secondary circuits is always the same, expressed by the equation $V_1 I_1 = V_2 I_2$.

Earth-Free Principle

The safety principle of a static transformer where energy is transferred to the secondary coil by electromagnetic induction without an electrical connection to earth, protecting patients from earth shock.

Choke Coil

A device that produces self-induced electromotive force (EMF) when alternating current passes through it.

Low Frequency Choke Coil

A choke coil consisting of a large number of turns of insulated wire wound on a laminated soft iron core, featuring high inductance and used for low frequency currents ($50 - 100\,\text{Hz}$).

High Frequency Choke Coil

A choke coil consisting of a few turns of insulated wire wound on an insulating bobbin without an iron core, featuring low inductance and used for high frequency currents in the kHz range.

Self-Induced EMF Formula

The equation $e = -L \frac{di}{dt}$, where $e$ is the self-induced EMF, $L$ is inductance in Henrys, $di$ is change in current, and $dt$ is time taken.

Current Smoothing (Choke Coil)

The process where a choke coil produces self-induced EMF opposing sudden current changes according to Lenz's law, making the output current smooth and steady.

Frequency Filtering (Choke Coil)

The function of a choke coil where it exhibits high reactance to block high frequency components and low reactance to allow low frequency components to pass.