Inductors

Owned by Kevin Li
Last updated: 2022-06-22 by Julian Yam
3 min read

Draw the symbol for an inductor.

What is inductance?

  • Inductance is the ability for an inductor to store energy by storing the energy in a magnetic field created by the flow of electric current.

  • When current flows through a conductor a magnetic field builds up around it since the flow of current induces a magnetic field. Inductors store energy in the magnetic field

What is the equation for impedance of an inductor?

Impedance is measured in ohms

X=2 pi f L

where..

X: Impedance (Ohms)

f: frequency (Hz)

L: Inductance

What is the differential equation for an inductor?

L: Inductance, physical property of the inductor

t: time

i = current flowing through the inductor

v: voltage

How does an inductor behave when initially excited and at DC steady-state?

Initial:

  • When an inductor is initially the inductor acts as if there is an open circuit voltage where the inductor is.

Steady State:

  • During steady state there is no voltage across the inductor and can be considered short circuit

What happens when an inductor saturates?

When an inductor saturates the inductor can be considered in steady state. There will be no voltage drop across the inductor and the circuit will behave as if the inductor is not there.

What do cores do on inductors?

Most inductors have a magnetic core inside the coil of wire. This is to increase the magnetic field that current induces thus the core also increases the inductance of the inductor.

What are typical core materials?

Common materials which the core is made out is is iron or ferrite.

What are the main loss mechanisms of an inductor? Where do they arise from?

Inductors lose power due to several different mechanisms:

  • Resistance in the coils

  • Magnetic friction in the core

  • Eddy currents

  • Physical vibration and noise in the core. Energy being converted to kinetic energy or sound energy.

What is ACR? Where does it arise from and how is it impacted by frequency?

ACR = Automatic Circuit Recloser

What sort of signals can inductors pass through and block? What sort of filter behavior is this?

  • Inductors’ impedance increases with increasing frequency. By having a high impedance component such as an inductor in series with a load, the inductor can block high- frequency signals from getting to the load. Blocking high frequency signals with an inductor is called a lowpass filter. An example of a low pass filter is shown below.

 

The figure above depicts how you make a high pass filter with a capacitor

  • A high pass filter is the opposite of a low pass filter. Instead of blocking out high frequency signals the high pass filter blocks low frequency signals

What are some common failure modes of an inductor?

  • Corrosion or bad internal solder joints can cause an inductor to fail

  • Inductors can be shorted due to electrical overstress

Source

https://www.electronics-tutorials.ws/inductor/inductor.html#:~:text=With a steady state DC, a very low value resistance.