- #1
ssana
- 13
- 0
Dear all,
I am working on PID loops now a days and need to know the exact description of PID control.
From TOHO TTM-X04 temperature controller, i learned about P and I, but still i can't understand about D (Differential). As you know that this temperature controller shows manipulated output in %.
Below are the observations i learned about P and I,
Proportional band only check the difference between actual value and set value and decide how much output in percentage is required to reduce this difference.
Example:
If P=1%
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 80% (assume)
If P=2%
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 60% (assume)
Conclusion is that manipulated output reduces as we increase the value of P in %.
Integral band increases the output if the difference remains unchanged.
Example:
If P=2% and I=300 Seconds or 5 minutes.
At 0th second of control time:
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 60% (assume)
At 300th second of control time:
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 100% (assume)
Conclusion is that output increases gradually and becomes full 100% in 300 seconds if present value remains 80 deg C.
Kindly share information about differential, as i am still struggling in getting clear information about differential.
Thanks to all
I am working on PID loops now a days and need to know the exact description of PID control.
From TOHO TTM-X04 temperature controller, i learned about P and I, but still i can't understand about D (Differential). As you know that this temperature controller shows manipulated output in %.
Below are the observations i learned about P and I,
Proportional band only check the difference between actual value and set value and decide how much output in percentage is required to reduce this difference.
Example:
If P=1%
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 80% (assume)
If P=2%
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 60% (assume)
Conclusion is that manipulated output reduces as we increase the value of P in %.
Integral band increases the output if the difference remains unchanged.
Example:
If P=2% and I=300 Seconds or 5 minutes.
At 0th second of control time:
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 60% (assume)
At 300th second of control time:
Present Value = 80 deg C
Set Value = 100 deg C
Difference = 20 deg C
Manipulated Output = 100% (assume)
Conclusion is that output increases gradually and becomes full 100% in 300 seconds if present value remains 80 deg C.
Kindly share information about differential, as i am still struggling in getting clear information about differential.
Thanks to all