I need information regarding transients?

[Sajjadkhan]

Hi all,

I have never dealt with transients, i know they exist during inductor discharge, switching some inductive load. What are the other reasons of transients?

I am going to do Master is power electronics and i am preparing this year for its prerequisites. So i need an oscilloscope and i have heard that low sampling rate oscilloscopes can not catch transients and i agree. that's why i am going to buy an Analog Oscilloscope.

I know transient is a spike that have a very narrow bandwidth, right? So what bandwidth of transients am i going to face in my field so i can buy oscilloscope according to it.

Thanks.

 

[Raza]

Hi sajjad,
A transient is known as (in electrical/electronics circuits) a sudden pulse of voltage or current can differ in Magnitude and period. Just for an example see the attached image:

It depends what type of transients you are going to work on. Better to buy a scope with high sampling rate as you are not going to change this very often.

 

[WimRFP]

Transients can have their origin in your circuit, but also outside your circuit (mains transients due to lightning or switching).

If the come from your circuit and your circuit use periodical signals, you can use an analog oscilloscope, however when they appear infrequently, you need real time digital storage oscilloscope to catch it when it occurs.

Transients are phenomena of short duration and have therefore wide bandwidth.

ESD transients (see it as human capacitor discharge) can be very fast (< ns rise time), but transients from mosfet switching may be in the ns range or even more. Depending on what type of transients you expect, you need to assess the required bandwidth and sample rate.