Inductors: An Introduction

Inductors are categorized on the basis of inner core like hollow core, solid iron core or soft ferrite core. There are some parameters & specifications of inductors which we need to introduce while talking about this electrical component.

1. Inductance: 

This is the key parameter for an inductor as it opposes any change in the current flowing. Inductance is coded as Henry or H and it's called its SI unit too. The actual level of inductance depends on several factors like number of turns on the coil, coil diameter and also the core used within the coil.

2. Time Constant of an Inductor: 

Current doesn't change all of a sudden inside an inductor as the current would need to change by a finite amount in zero time. It would make the induced emf infinite and infinite voltages don't exist. The if current changes rapidly through an inductor, then high voltages are induced across the inductor coil.

3. DC Resistance: 

Inductors are manufactured from thin wire, thus making DC resistance very significant. If thicker wire is used, then also DC resistance is important in relation to an inductor's overall performance. DC resistance is measured with steady current in Ohms and it's given maximum value most of the time.

4. Current and voltage in Inductor: 

Induced voltage amount depends upon the rate of current change. An induced emf always opposes the change which took place for the first time. So reducing current is resulted from voltage polarity as a source and increasing current is resulted from voltage polarity as a load.

5. Power and energy in Inductor: 

As an inductor in a circuit opposes the flow of current, then the actual work is done by an external battery source to keep the current flowing against induced emf. So power is an important factor for inductors. When power flows, energy gets stored in the magnetic field.

6. Saturation Current: 


In an inductor the core can be saturated as there is a limit to the level of magnetic flux. If relative permeability falls, the level of inductance also drops.

7. Incremental current: 

This parameter is taken as the DC bias current flowing through the inductor which causes inductance to fall by 5 per cent from its initial value with zero bias. The value indicates the level where a further increase can take place. The incremental current value is quite important for an inductor while using ferrite cores.

8. Core permeability: 

It's another key parameter as it governs the inductance of the inductor for a given inductor geometry. The higher permeability core means higher level of inductance.

9. Winding self-capacitance: 

It's an important parameter for several applications as the wires have a small but impressive level of capacitance between each other. The level of capacitance depends on the area of the wire, the distance between the two wires and the permittivity of the material between them.

10. Self resonant frequency: 

The inductor forms a parallel resonant circuit and when the inductor resonates inductive reactant and capacitive reactant, they cancel each other out and the circuit's impedance falls to a value which is governed by DC resistance.

Courtesy: Electronics Tutorials and Radio Electronics 
Sanchari Banerjee, EFYTIMES News Network