Punjab Technical University 2005 M.Tech Electronics and Communication Engineering INSTRUMENTATION & CONTROL ENGINEERING EC 501 - Question Paper

INSTRUMENTATION & CONTROL ENGINEERING EC 501 2nd/ third Sem May 2k5

Max marks 100


Note: Attempt any 5 ques.. All ques. carry equal marks.

1. elaborate the basic blocks of a generalized instrumentation system? Draw the different blocks and discuss their functions with suitable examples.

2. (a) what is Holography? discuss its principle. Enumerate the applications of holography.

(b) a d’Arsonval galvanometer is a 2nd order instrument. It has a spring stiffness such that a torque of 40 micro N/m provide a steady defection of 90 degrees. If the inertia of rotating parts is 0.5 x 10-6 kgm2 and the damping constant is five micro Nm/rad sec -1, determine the damping ratio, the natural angular frequency, the frequency of damped oscillations and the time constant of the movement. Determine the steady state dynamic fault when the input voltage is increasing at a steady rate of five V/s.

3. (a) What is strain gauge? discuss with a circuit diagram the principle of operation of a strain measurement system having arrangement for temperature compensation.

(b) a Venturi-tube of throat diameter six cm is placed in a water pipe of diameter 10 cm to measure the volumetric flow of rate which is obtained to be 0.08 m3/s. If the density and viscosity of water are 103 kg/m3 and 10 x 10-4 Pa.s, respectively, determine the Reynolds number for these conditions. provided that the discharge coefficient is 0.99, determine the upstream t throat differential pressure developed.

4. (a) define the various methods used for measurement of thickness. explain their advantages and disadvantages.

(b) A bimetallic strip element has 1 end fixed and other free, with the length of cantilever being 40 mm. The thickness of every metal is one mm, and the element is initially straight at 20 oC. compute the movement of the free end in a perpendicular direction from the initial line when the temperature is raised to 180 oc. 1 of the materials is Invar with a negligible thermal expansion co-efficient while the 2nd is a nickel chrome alloy with an expansion co-efficient of 12.5 x10-6/oC.

5. (a) Develop the transfer function of armature controlled d.c. shunt motor.

(b) The transfer function of a control system is

G(s) = 1000(s+3)/[s(s+12)(s+50)]
Draw the Bode plot.

6. (a) elaborate the necessary and sufficient conditions for stability using Routh Hurwitz criterion? A characteristic formula of a feedback control system is

S5 + S4 + 4S3 + 4S2 + 2S +1 = 0
Check the stability of the system.

(b) Let the unity feedback system have the open loop transfer function as

G (s) = K/[s(Js + F)]
discuss the features of proportional-plus-integral (P1) controller by comparing the response specification with the system without any controller for unit step input.

7. explain development and use of adaptive control system t computerized numeric control machines. How dos the control affect productivity? explain.

8. compare the electronic and pneumatic controllers. explain P, PD and PI control actions in pneumatic or electronic controllers.

Earning:   Approval pending.