FIXED INDUCTOR

FIXED INDUCTOR

An inductor uses multiple coils of a conducting material to store energy using a magnetic field. It belongs to the electromagnet family. The voltage produced is proportional to the rate of change in current flowing through it. The higher the number of coils and input current, the higher is the inductance.

Working of a fixed inductor

Coils of high conducting material like copper or aluminum are wound around a core of ferrous material. When electric current is passed through the coil, a magnetic field is created. A change in current produces a change in this magnetic field and causes an electromotive force. It runs against the current that induces it and this produces a voltage in the direction opposite to the change in current. This voltage is called inductance. The unit of measurement is the Henry (H). The ferrite core induces more capacitance.

Selecting a fixed inductor

Ideally, inductors should have zero resistance and capacitance. This is not practically possible, as the conducting copper wires, used for fixed inductors, have small internal resistance.

Important criteria for the selection are:

Inductance range (H): the rated inductance range of the inductor. This is designated by -/+10% of the inductance (e.g. 15+/-10%).
Quality factor (Q): measure of the relative losses in the capacitor.
Self-resonant frequency (SRF): lowest frequency at which an inductor resonates due to its self capacitance (e.g. 150 MHz).
Permissible DC current: measured in Ohms, it is the maximum DC current that the inductor should be exposed to.

Fixed inductor types:

Fixed inductors are classified as per their inductance range, surface mount, tape and reel and the number of coils. They are also color-coded in bands of brown, black, silver, green, etc.

Application areas for fixed inductors:

They are used in electronic equipment, such as communication apparatus, automatic control equipment, electronic testing instruments, household appliances, electrical equipment, radios, TVs, etc.