CIS108-2 Dynamics Measurements And Control

CIS108-2 Dynamics, Measurements And Control Assessment Solution

Section A: Short Answer Questions

• Answer All Questions in SECTION A
• Each question carries 5 marks

Question 1

Find the equivalent resistor (R total) for the network presented in Figure 1A.

                                  Figure 1A                             [5 Marks]

Answer;

Equation R

= R3 +R4+ R3

=4+2+1

=7

Req= R2 + Req

=1/2 + 1/7

=9/14

= 0.64

Req= 9/14 +4

= 9+56/14

= 65/14

Req = 4.64

Question 2

You have been given a task to select a sensor; name four different selection criteria for your sensor selection, briefly explain two of them.

                                                                             [5 Marks]

Answer:

1. Temperature
2. Size
3. Protection Glass
4. Discrete or analog input

Question 3

Using a simple diagram, briefly explain the speed- torque relation for a DC motor.

                                                                            [5 Marks]

Answer:

DC motors are relatively simple machines.

When supply voltage is constant, the Torque T is inversely proportional to speed W.

Question 4

For the circuit presented in Figure 2A, find the current I and 𝑉_𝑜, if the diode is a silicon type

( 𝑉_𝐷 = 0.7 𝑣𝑜𝑙𝑡𝑠)

                                                                           [5 Marks]

Answer:

Vd = 0.7V

I = V1R1 - V2R2

=8×1.2 -4.7×0.7

=9.6 - 3.29

=6.31

V = Vin - Vg

=8 - 6

V=2V

Question 5

Overall transfer function for a control system is given by:  T(𝑠) = 3

𝑠2+8𝑠+3

Considering the damping factor, which type of the system, this transfer function demonstrates?

Answer:

T(s)= 3/ s2+8s+3

T(s) =8/2 =4

T(s) =4>1

So overdamped

Section B: Long Answers Questions

• Answer any 3 (THREE) questions
• Each question carries 25

Question 1

1.Find the total current and the total power dissipated in circuit of Figure

                                                                           [12 Marks]

Ans:                                              

1. Figure 2B presents a bridge circuit to measure the If Rsensor is 650 Ω, calculate the 𝑉_{𝑜𝑢𝑡𝑝𝑢𝑡}.

                               Figure 2B

                                                                             [5 Marks]

1. For the network of Figure 3B,

a. write the mathematical expressions for the current 𝑖𝐿 and the voltage 𝑉𝐿 following the closing of the switch.

b. How long does it take for the 𝑖𝐿 to reach its maximum level?

                                                                            [8 Marks]

Question 2

a. Find the equivalent capacitor between terminal A and B in Figure If a voltage of 40 V is applied across the terminal AB, calculate the energy stored in equivalent capacitor in Joules.

                                   Figure 4B

b. The combinational logic system presented in Figure 5B, accepts 2-bit binary numbers. Complete the Truth table below for this system.

                            Figure 5B

Question 4

1. Find the close loop transfer function for the system presented in Figure

                                                                           [10 Marks]

1. Using Routh-Hurwitz method, determine if the control system presented in Figure 7B is stable or not. Why?

                                                                             [8 Marks]

Routh-Hurwitz method, so its not stable.

1. Using a general diagram, present main components of a pneumatic

                                                                             [7 Marks]

S- Domain

𝑒^{−𝑎𝑡} sin 𝜔𝑡

Formula Sheet

U = ½CV²

𝜀𝜀0 = 8.854 × 10-12

μ0 = 4π × 10−7 H/m

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