Dear Team,

I am simulating a circuit which contains PT100.I modelled PT100 as shown in the below schematic.While running simulation I am getting the below error.
The complete schematic is attached along with this.



Can you please help me to solve this issue

 

Hi hoy,
Try it with Pt=100 as per this clip, the sim runs forever.
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Try it with PT100={your expression}

 

You need an equal sign in your param definition

PT100=(…

 

Hi hoy,
This is a basic test of the control section, using a fixed100R for the PT100.
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Hi hoy.
You have drawn this INA upside down compared to the circuit posted in your other thread.
+In and -In
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Hi hoy.
You have drawn this INA upside down compared to the circuit posted in your other thread.
+In and -In
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View attachment 332814

Thank you Erric.
It was a mistake from my side I will correct it.

 

You need an equal sign in your param definition

PT100=(…

Hi ,

I updated the equation .still I am getting error please see the below image.

 

Hi hoy,
Checking your equation shows this result for Pt resistance, the basic equation is wrong, where did you fid it?
Stepping from 10C thru 60C in 10C steps
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Hi hoy,
LTS uses this expression for 'e'
R= {100 * (1+3.85* exp(-3) *TEMP)}
It works, but slowly, also the basic equation itself is suspect

Update:
@hoyyoth
Check your equation for the Add sign!

R= {100+(1+3.85* exp(-3) *TEMP)}


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This is for 10C with V3 at 0.5V

 

Hi Erric,

Thank you.
May I I know why you are using this ".options cshunt =10f gshunt=1n abstol=1n vntol=1m"

I got the equation from here(https://de.wikipedia.org/wiki/Platin-Messwiderstand) and this one also

https://autosen.com/en/Worth-knowin...VjE5ER3DwymUe0XAfE_4x5wefUZDnCOH0OR5o_XNUFr93

 

This should work
PT100={100*(1+temp*3.85e-3)}

 

yes it is working...

 

Hi Alec
Check your equation, the * sign gives resistance results off the scale.

100*( 1 + 100 * ( 3.85 ^ Exp( - 3)))=10,794.2R @100C

It should be a + sign, please check.

Pt=100 +( 1 +100 * 3.85^ Exp( - 3)) = 207.9R @ 100C

Which also disagrees with the published PT100 values??

I think 'hoy' should recheck the actual equation

Eric

 

Hi hoy,
This is a reference test simulation and table for a typical PT100 0C thru 100C

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Hi hoy,
Try this option,
The output circuit from the Pt100 has been deleted in order to speed up the simulation
All that circuit does is convert the Diff signal to single ended and a buffer, overall gain is unity.

This sim runs a temp from 0C through 100C
Note the method for controlled the Pt100 value, the V3 input is fixed at 2v for the test
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