When does Proportional (p.) Integral (I) Derivative (D) Controllers are Used ?
When Proportional (P) Controller is Used during the following conditions:
- Load Changes are small
- Offset (error exist due to difference between steady state value and desired value) can be tolerated
- The process reaction rate is such as to permit a narrow proportional band. Since this reduces the amount of the offset
When Integral (I) Controller is Used during:
- When the offset must be eliminated
- Integral saturation due to sustained deviation is not objectionable
When Derivative (D) Controller is used:
- Large transfer or distance velocity lags are present
- It is necessary to minimize the amount of deviation caused by the system changes
When Proportional plus Integral (PI) Controller is used when:
- System changes is small
- Offset must be eliminated
- No objection on the recovery duration
When Proportional and Derivative (PD) controller is used:
- When the system changes are small
- Improve the recovery time
- When system lags are high
When Proportional, Integral and Derivative (PID) Controller is used when :
- System changes are small
- Offset must be eliminated
- Fast recovery time