Process Control and Instrumentation MCQs 2026

Bode plot shows

1. Aonly time step response only✓
2. Bonly XY composition✓
3. Conly tray temperature profile only✓
4. Dgain and phase versus frequency✓

Ultimate gain in Ziegler-Nichols closed-loop method found at

1. Acritical gain causing sustained oscillation✓
2. Bzero gain always✓
3. Cmaximum sensor span✓
4. Dminimum reflux✓

Feedforward control acts on

1. Aonly past error integral✓
2. Bonly operator guess✓
3. Cmeasurable disturbance before it affects controlled variable✓
4. Donly annual maintenance✓

Cascade control uses

1. Aonly single sensor far downstream✓
2. Bonly open-loop scheduling✓
3. Csecondary loop to correct disturbance before primary loop✓
4. Donly laboratory off-line tuning✓

Second-order overdamped response has

1. Asustained oscillation always✓
2. Binverse response only always✓
3. Cundefined output✓
4. Dno oscillation✓

Transfer function G(s) relates

1. Aonly time-domain impulse visually✓
2. Bonly pipe schedule✓
3. Conly catalyst surface area✓
4. DLaplace transform of output to input✓

Derivative mode responds to

1. Aonly steady error magnitude✓
2. Bonly setpoint constant always✓
3. Crate of change of error✓
4. Donly manual mode✓

Integral mode eliminates

1. Asteady-state offset for step disturbance in stable loop✓
2. Ball oscillations instantly always✓
3. Cneed for sensor✓
4. Dprocess time delay completely✓

PID controller combines

1. Aonly on-off relay without hysteresis✓
2. Bproportional, integral and derivative actions✓
3. Conly ratio without measurement✓
4. Donly cascade without secondary✓

Feedback control compares

1. Aonly feedforward without measurement✓
2. Bmeasured variable to setpoint and corrects via controller output✓
3. Conly manual valve position always✓
4. Donly laboratory assay weekly✓