shubhampaul

modified 7 years ago

Another EC Error- check circuit topology

129

01:21:51

The circuit could have been used to see the current distribution between the inductors before steady state (transient response) but I get the error as "check circuit topology"

published 7 years ago

kiani

7 years ago

EC inductor does not include a series dc resistance. So the dc resistance of EC inductor is zero.. EC can not allow divide by zero,, as x/0 = nonsense. So you need to put a resistor equivalent to dc resistance of an inductor in series with it. Ok?!

kiani

7 years ago

Each inductor has to have its own series resisrance

shubhampaul

7 years ago

😭 thanks again.. But that would change my ideal current value through that inductor at a particular time if I shift the dc resistance to the inductors.

kiani

7 years ago

Well in real life inductors do have a series resistance... And unfortunately no one had been able to get anything than nonsense from dividing by zero (calk it infinity), you could try putting a 1u ohm resistor in series, which had minimal effect,.

shubhampaul

7 years ago

Yeah I tried that but I suppose EC is not designed to support showing transients at t=0+ (just after the simulation starts or when the source is activated) ... So it's not useful anyway.

ViolationMad

7 years ago

I don't understand why you would do a DC analysis of ideal inductors... Doesn't make a lot of sense. If you apply the limes to the coil resistance and let it run against 0, you will get an infinite current.. So your current will just be limited by 1ohm. Here are some comparisons: http://everycircuit.com/circuit/5044254102781952

shubhampaul

7 years ago

@ViolationMad it makes sense because this question was asked in a competitive exam I am preparing for... The question was to find the "time" when the current through the 2H inductor is 2A.

shubhampaul

7 years ago

I needed the DC transient response.

shubhampaul

7 years ago

@ViolationMad and @kiani . I think the problem is that EC is trying to determine the steady state circuit before simulation starts which is why it can't handle "two parallel zero resistance wires (inductors at Steady state)" .

kiani

7 years ago

this problem can be soled if you add a switch in cct. And turn cci. On after you press the play botton. It is because EC always does a dc op followed by transient. Before it starts. So what you are getting is the result and no current flow..

shubhampaul

7 years ago

I tried adding a switch but still the same error :-(

kiani

7 years ago

http://everycircuit.com/circuit/6142458315669504

kiani

7 years ago

Chk. This

shubhampaul

7 years ago

Awesome!! Reducing the resistance to 10u ohm and setting the simulation time to 113ms/s gave me perfect results because of your switch. The answer is 340 ms at 2A which becomes 3 sec of real time. Thanks a lot!

shubhampaul

7 years ago

Wow I didn't know a switch can make such a difference 😅

kiani

7 years ago

That is good news,,, this is how EC works,, at switch on it removes capacitorscan d inductors and then it does a dc op followed by transient, then it puts the chsrged capacitors and inductors bsck in the circuit. Si there is no current flow,. At seich on, just the result. Adding a switch. Allows the csos. Snd inductors to charge ( current flows) at swich on. So i always have a switch for sll my circuits to stop EC putting chsrged caps. In circuit. Therefore allowing, to observe initial current flow at switch on.

shubhampaul

7 years ago

Thanks for the info and help 😀

kiani

7 years ago

No problrm,, i had this problem too plus many other ones which you will probably come across with.. The problem is there is no manual for this app,. I have been petitioning for, but still no manual of any sort..

2ctiby

7 years ago

@shubhampaul ... Nice job getting 340 ms at 2A ... What do you mean there when you say 'which becomes 3 sec of real time' ?

shubhampaul

7 years ago

@2ctiby. See the actual answer that I calculated using the equations equals to 340ms (when the inductor current reaches 2A)... To verify that I had to match the simulation time with the real time (to keep a track of much time has passed as EC doesn't show that in the graph) ... So I set the simulation time to 113ms/s which means "113ms of simulation time equivalent to 1sec of real time"... So starting the simulation and ending it within 3 sec of real time would give me 113*3=339ms (almost 340ms) of simulation time at which the current should be 2A and it was 2A when I did that.

kiani

7 years ago

Genius.

2ctiby

7 years ago

@shubhampaul ... Nice, thanks, that clarifies it ... I was wondering if you were referring to the 5 x tau of 3.3 sec for the full voltage curve to develop from start down to zero or talking about its 2A, 340ms point of 9.0v etc.

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