Definition of transient??

[Learner]

Hi guys,
I was wondering if anyone can explain what transient is or what exactly is the definition of transient in electrical engineering?

 

[eng_Semi]

The transient is the behaviour of the circuit (for example) after a certain action, and this behaviour didn't last for a long time. After this transient period the steady state behaviour dominate, i.e. the steady state solution is at t tends to infinity.

For example, if u have a circuit consist of a batter, a switch, and a capacitor (in series). If initially the switch is opened, and at a certain time the switch was closed. The capacitor begins to charge exponentially (ehich is the transient) and after a while its voltage is fixed to the battery voltage (steady state)

 

[Learner]

What determines/classify the start of the steady state?

In the example mentioned, after the first time constant the voltage in the cap will be charged up to 70% of the supply voltage and after 5 time constant the voltage will be close to the supply voltage. Would the stead state be considered to have started at the begining of the second time contant third or forth etc...?

Thanks eng_Semi!

 

[nzahirov]

The steady state is the result as t approaches infinity. You can also define this in terms of settling time and say that the system has reached steady state once the output is bounded by +/- 1% of its final value.

 

[electronics_kumar]

1)Presence of Energy storage elements(L and C) will lead to formation of transients in any electrical circuits

2) as we know all electrical circiuts can be expalioned by differential equation.
If it is so means, ceratinly willl have particular and complete solution. That PARTICULAR SOULTION will give you transient state and copmplete soultion will give you staedy state information


3) Tranisient will have overshoot

Finally it cane mitigated by means of PD CONTROLLERS (DIFFERATIOR WILL INCREASE AMOUNT OF DAMPING.. WHICH WILL FINALLY HINDER TRANSIENT)

 

[Learner]

The steady state is the result as t approaches infinity. You can also define this in terms of settling time and say that the system has reached steady state once the output is bounded by +/- 1% of its final value.

Is the +/-1% a commonly used rule in EE to define the start of steady state?

Added after 12 minutes:

1)Presence of Energy storage elements(L and C) will lead to formation of transients in any electrical circuits

How does the reactive components influence or effect the transient? I mean, what is the direct result of L and C in relation to the transient response? eg. the outcome of the transient when L approaches 0 vs L approaches infinity?

Same as C, what is the outcome of the transient when C approaches 0 vs C approaches infinity?

3) Tranisient will have overshoot

Finally it cane mitigated by means of PD CONTROLLERS (DIFFERATIOR WILL INCREASE AMOUNT OF DAMPING.. WHICH WILL FINALLY HINDER TRANSIENT)

Does the overshoot gets critically damped if the inductive reactance cancels out with the capacitive reactance? ie when the load becomes only resistance?

 

[Learner]

Any more thoughts on the topic guys?

 

[malikanwer]

well i will talk with a daily life example,let say u have a long clean road n u want to drive ur car at const speed of 100km/hrs so inorder to get that speed at first u need to start ur vehicle if it is at rest and it will take some time to reach that speed,that time can be called transients to come to ur reqd speed.now u use that analogy n consider car as ur oscillator n speed as ur frequency n when u switch on ur circuit it will take some time to com to ur specified freqyency so u will always get some transients before reaching ur requirements
.

 

[gbaerf]

or in other way
in any short of circuit designing using CAD tools we keep out circuit in transient state till we get our desired output ....ones we get desired output then the circuit will be in steady state
means when a circuit is changing ( or transferring ) from one state to another in terms of or with respect to any parameter then it is in transient state.
all the dynamic mathematical calculations such as for a simple example calculation of a dynamic resistance because of the ration of changing voltage to changing current comes under transient analysis.