The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is________________?

Related Mcqs:

1. Suppose that the gain, time constant and dead time of a process with the following transfer function: Gc(s) = 10 exp( – 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as________________?

   A. 8, 0.6, 0.08
   B. 12, 0.6, 0.12
   C. 8, 0.6, 0.12
   D. 12, 0.4, 0.08

2. A first order system with a time constant of 1 min is subjected to frequency response analysis. At an input frequency of 1 radian/min, the phase shift is______________?

   A. 45°
   B. -90°
   C. -180°
   D. -45°

3. According to Bode stability criterion, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is_________________?

   A. 0°
   B. 45°
   C. 90°
   D. 180°

4. A first order system with unity gain and time constant η is subjected to a sinusoidal input of frequency w = 1/η. The amplitude ratio for this system is______________?

   A. 1
   B. 0.5
   C. 1/√2
   D. 0.25

5. The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function ?

   A. e-ηS
   B. (T1S + 1)/(T2S + 1)
   C. (T1S/(T2S + 1)
   D. (T1S + 1)/(T2S

6. Phase lag of the frequency response of a second order system to a sinusoidal forcing function______________?

   A. Is 30°
   B. Is 90° at the most
   C. Approaches 180° asymptotically
   D. Is 120°

7. “A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is _______________ criterion?

   A. Bode stability
   B. Nyquist
   C. Routh stability
   D. None of these

8. Phase lag of the sinusoidal response of a first order system is _________________?

   A. 120°
   B. 30°
   C. 180°
   D. 90°

9. Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function Gp(s) = 1/(4s + 1)(2s + 1)(s + 1) ?

   A. w = 1/√14, Kc = 45/7 √14
   B. w = √(7/6), Kc = 46/3
   C. w = 1, Kc = 13
   D. w = √(7/8), Kc = 45/4

10. The frequency response of a first order system, has a phase shift with lower and upper bounds given by________________?

    A. – ∞, π/2
    B. -π/2, π/2
    C. -π/2, 0
    D. 0, π/2