Resistance Temperature Detector (RTD) response time

[JohnielWhite]

How would u work this problem?

Q-If a RTD has a time constant of 10.0secs, approximately how long will the sensor take to get with 5% of the final value?

I am thinking two ways to approach this problem.

S1- It is known that the RTD takes 5 time constants to reach its final value, hence t=5T=5*10=50sec.

Or

S2- If 63%t=10 => t=10/63% => t=15.87sec Now 95%t=95%*15.87=15.08sec

I'm not sure which if any of these are correct. please let know know if I am approaching this correctly. Thanks.

 

[berkeman]

How would u work this problem?

Q-If a RTD has a time constant of 10.0secs, approximately how long will the sensor take to get with 5% of the final value?

I am thinking two ways to approach this problem.

S1- It is known that the RTD takes 5 time constants to reach its final value, hence t=5T=5*10=50sec.

Or

S2- If 63%t=10 => t=10/63% => t=15.87sec Now 95%t=95%*15.87=15.08sec

I'm not sure which if any of these are correct. please let know know if I am approaching this correctly. Thanks.

The response is exponential. Do you know how to write the equation for the response versus time?

R(t) = _________

The "time constant" you are given appears in the right side of the equation...

 

[JohnielWhite]

yes i do...

T(t)=Tinitial + (Tfinal-Tinitial)(1-e^(-t/T))

I got the value of t to be 29.9sec after 95%

Thanks for your response...