lab manual control systems lab - vsm.edu.in

VSM COLLEGE OF ENGINEERING

LAB MANUAL

CONTROL SYSTEMS LAB III B.TECH I SEM (JNTUK)

ELECTRICAL AND ELECTRONICS ENGINEERING DEPARTMENT

V S M COLLEGE OF ENGINEERING

RAMCHANDRAPURAM

E.G DISTRICT

533255


INDEX

Exp

No. Date Name of Experiment Page

No.

Marks Signature

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Time Response Of Second

Order System

Characteristics Of Synchros

Effect Of Feed Back On Dc

Servo Motor

Transfer Function Of Dc

Motor

Transfer Function Of Dc

Generator

Temperature Controller Using

PID

Characteristics Of Magnetic

Amplifier

Characteristics Of AC Servo

Motor

Lag and Lead Compensation

Characteristics Of DC Servo

Motor


1. TIME RESPONSE OF SECOND ORDER SYSTEM

AIM: To study time response of second order system.

APPARATUS: Second order system kit, CRO, Patch chords.

THEORY: The time response of the second order control system to square input often

exhibits damped oscillations before the steady state and also depends on the initial

conditions. The second order system is C(s)/r(s) =ωn2/s2+2fωns+ωn

2.

The transient response of a practical control system often exhibits damped

oscillations before reaching steady state. A typical oscillatory response of the second

order system is shown in figure.

t

c(t)

2% or 5%

tptrtd

1

0

Mp

0.5

c(tp)

ts

For δ = 0.158, C = 0.01µF, L = 100mH, R = 1KΩ

ωn = 1/ √(LC) = 1/√(100 x 10 -3 x 0.01 x 10 -6)

= 31622 rad/sec

ωd = ωn√ (1-δ2) = 31622 √ (1- 0.1582)

= 31224 rad/sec

(a) Delay time (td): It is time taken for response to reach 50% of the final value, for the

very first time.

td = [1+ 0.7δ] /ωn seconds.

td = [1+ 0.7 x 0.158] /31622

= 35.12 μs

(b) Rise time (tr): It is the time taken for response to raise from 0 to 100% for the very

first time. For under damped system, the rise time is calculated from 0 to 100%. But for

over damped system, it is the time taken by the response to rise from 10% to 90%. For

critically damped system it is the time taken for response to rise from 5% to 95%.

tr = (Π- θ) / ωd


θ = tan -1 ((√1- δ2) / δ) = tan -1 ((√1- 0.1582 ) / 0.158) = 80.900 = 1.42 rad

tr = (Π- θ) / ωd = (3.142 – 1.42) / 31224 = 55.14 μs

(c) Peak time (tp): It is the time taken for the response to reach the peak value for the

very first time, or it is the time taken for the response to reach the peak overshoot, Mp.

tp = Π /ωd = 3.142/31224 = 100.62 μs

(d) Peak overshoot (Mp): It is defined as he ratio of the maximum peak value measured

from final value to the Mp.

% Mp = [e-δΠ / (√(1-δ))] x100

= [e-0.158Π / (√(1-0.158))] x100

= 66.33 %

(e) Settling time (ts): It is the time taken by the response to reach & stay within a

specified error. i.e., either 2% or 5% of the final value.

ts = 4/ δωn for ± 2% tolerance.

ts = 4/ 0.158 x 31622 = 0. 8 ms

ts = 3/ δωn for ± 5% tolerance.

ts = 3/ 0.158 x 31622 = 0.6 ms

CIRCUIT DIAGRAM:

R L

C CROSTEP Vo

+

-

+_INPUT

V


PROCEDURE:

1. Connections are made as per the circuit diagram.

2. The square input of 10 Volts is applied to the circuit by using function generator.

3. The output waveform across the capacitor is observed in the CRO.

4. The values of td, tr, tp, mp, and ts are measured from the output waveform.

5. The output waveform is drawn on the graph sheet.

OBSERVATIONS:

Sl. No. Theoretical values Practical values

td 35.12 μS

tr 55.14 μS

tp 100.62 μS

Mp 66.33 %

ts 0. 8 mS for ± 2%

0. 6 mS for ± 5%


RESULT:

VIVA QUESTIONS::

1. Define the following

a) Delay time b) Rise time c) peak time d) peek over shoot e) settling time

Ans. (a) Delay time (td): It is time taken for response to reach 50% of the final value, for

the very first time.

(b) Rise time (tr): It is the time taken for response to raise from 0 to 100% for the very

first time. For under damped system, the rise time is calculated from 0 to 100%. But for

over damped system, it is the time taken by the response to rise from 10% to 90%. For

critically damped system it is the time taken for response to rise from 5% to 95%.

(c) Peak time (tp): It is the time taken for the response to reach the peak value for the

very first time, or it is the time taken for the response to reach the peak overshoot, Mp.

(d) Peak overshoot (Mp): It is defined as he ratio of the maximum peak value measured

from final value to the Mp.

(e) Settling time (ts): It is the time taken by the response to reach & stay within a

specified error. i.e., either 2% or 5% of the final value.

2. What are the different types of responses that are present in a system?

Ans. Two types of responses are there 1. Steady state response 2. Transient response

3. What are the reasons for transient Response?

Ans. Parameters variations (i.e L, C), input supply variations and switching ON and OFF

of supply.

4. Define steady state error?

Ans. It indicates the error between the actual output and desired output as‘t’ tends to

infinity.

5. What is a type and order of a system?

Ans. In the open loop transform function of a system, the number of poles at origin gives

the type number and the highest order in the denominator of closed loop transform

function gives the order number of that system.


2. CHARACTERISTICS OF SYNCHROS

AIM: To determine characteristics of Synchro Transmitter and Synchro Receiver.

APPARATUS: Synchro Transmitter and Receiver Kit, Patch Chords.

THEORY:

Synchro is an electromagnetic transducer commonly used to convert an angular

position of a shaft into an electric signal. The basic synchro is usually called a synchro

transmitter. Its construction is similar to that of a three phase alternator. The stator is of

laminated silicon steel and is slotted accommodate a balanced three phase winding which

is usually of concentric coil type ( three identical coils are placed in the stator with their

axis 120 degree apart ) and is star connected. The rotor is a dumb bell construction and

wound with a concentric coil.

An AC Voltage is applied to the rotor winding of synchro transmitter through slip

rings. This voltage causes a flow of magnetizing current in the rotor coil which produces

a sinusoidally time varying flux directed along its axis and distributed nearly

sinusoidally, in the air gap along stator periphery. Because of transformer action, voltages

are induced in each of the stator coils. As the air gap flux is sinusoidally to the cosine of

the angle between rotor and stator coil axis and so is the voltage induced in each stator

coil.The stator coil voltages are of course in time phase with each other. Thus the synchro

transmitter acts like single phase transformer in which rotor coil is the primary and the

stator coils form three secondary’s.

The synchro receiver is having almost the same constructional features of synchro

transmitter.

CIRCUIT DIAGRAM:


STUDY OF SYNCHRO TRANSMITTER:

(a) PROCEDURE:

1. The supply is given to the kit.

2. The synchro transmitter rotor position is rotated in steps from the zero position to the

maximum position and the corresponding readings of synchro transmitter rotor position

in degrees, stator voltages VS3S1, VS1S2 and VS2S3 are noted down.

3. The graph is plotted between stator voltages and synchro transmitter rotor position.

(b) OBSERVATIONS:

Sl. No. Rotor position

in degrees

Stator Terminal Voltage (RMS)

VS3S1 VS1S2 VS2S3

(c) GRAPH:


STUDY OF SYNCHRO TRANSMITTER AND SYNCHRO RECEIVER:

(a) PROCEDURE:

1. The terminals S1, S2, S3 of synchro transmitter are connected to the respective

terminals of S1, S2, S3 of synchro receiver.

2. The supply is given to the kit.

3. The synchro transmitter rotor position is rotated in steps from the zero position to the

maximum position and the corresponding readings of rotor positions of Synchro

transmitter and Synchro receiver in degrees are noted down.

4. The graph is plotted between rotor positions of transmitter and receiver.

(b) OBSERVATIONS:

Sl. No. Rotor position of

Synchro transmitter in degrees

Rotor position of

Synchro receiver in degrees

(c) GRAPH:


RESULT:

VIVA QUESTIONS:

1. What is a synchro?

a. Synchro is an electromagnetic transducer commonly used to convert an angular

position of a shaft into an electric signal.

2. What is "electrical zero" in a synchro transmitter?

a. When Φ =0, the emf induced in the coil S2 is maximum, while the line voltage VS1S3 is

zero. This position of the rotor is defined as electrical zero of the transmitter and is used

as reference for specifying angular position of the rotor.

3. What do you mean by synchro pair?

a. The interconnection of synchro transmitter and synchro control transformer ( Synchro

Receiver) is combined called as synchro pair.

4. What is the application of synchro pair?

a. it can be used as an Error detector. Synchros are widely used for transmission of

angular data.


3. EFFECT OF FEED BACK ON DC SERVO MOTOR

AIM: To study the effect of feed back on DC Servo motor.

APPERATUS: DC servo motor kit, Load and Patch chords.

THEORY:

The speed of the DC motor is controlled by the PID (proportional, Integral and

Derivative) controller method. The output of the controller then adjusts the value of each

variable in the control system until it is equal to predetermined value called a set point.

The system controller must maintain each variable as close as possible to its set point

value and it must compensate as quickly and accurately as possible for any change in the

variable caused by the motor.

CIRCUIT DIAGRAM:


PROCEDURE:


2. The speed of motor is kept at some value (set speed) by using set potentiometer.

3. The P, I & D controllers are switched on and their knobs are kept at maximum

position.

4. The load is applied on the motor in steps of 50 grams up to 250 grams.

5. The run speed is noted down at each load.

OBSERVATIONS:

P CONTROLLER ON [AT 50% SETTING]

Sl. No. Set Speed (rpm) Weight (grams) Run Speed (rpm)

P + I CONTROLLER ON [AT 50% SETTING]


P + D CONTROLLER ON [AT 50% SETTING]



P +I+ D CONTROLLER ON [AT 50% SETTING]


RESULT:

VIVA QUESTIONS:

1.Why the feedback is employed in control system.

a. It reduces the sensitivity of the system to parameter variations.

2. What is the physical requirement for a servo motor

a. Low inertia and high starting torque.

3, What is servo mechanism

a. A system that controls speed, temperature or position in releation to a reference is

known as servo mechanism.

4. What is the effect of negative feedback.

a. It reduces the effect of disturbance and noise signals in the forward path.

5. What is the advantage of D. C servo motors over A.C. servo motors

a. For very high power systems D.C servo motors are preferred because they operate

more efficiently than A.C. Servo motors.


4. TRANSFER FUNCTION OF DC MOTOR

AIM: To determine the transfer function of DC motor.

APPARATUS:

1. DC motor- 0.5HP/220V/1500 rpm with mechanical loading arrangement.

2. Controller unit suitable for the above motor to vary the armature voltage and field

voltage with Digital meters.

3. Tachometer Digital contact Tachometer to measure the speed of DC motor.

SPECIFICATIONS OF MOTOR:

DC Motor: 0.5HP/220V/1500 rpm

Armature Resistance = Ra =11 Ω

Armature Inductance = La = 225mH

TO DETERMINE KT:

(a) CIRCUIT DIAGRAM:


PROCEDURE:

1. Keep all the knobs at minimum position

2. Connect 3 pin power cords to mains supply

3. Connect motor field to 220V DC fixed power supply

4. Connect armature of the motor to 220V variable Power supply

5. Connect 230V AC to the MCB input of the unit at front panel from AC mains

externally (use isolation transformer)

6. Keep armature control knob of the motor at minimum position

7. Switch AC mains supply

8. Now slowly vary the armature supply knob of motor till motor reaches its rated speed

9. Now slowly load the motor upto max of 2A

10. Note armature current Ia and weights w1 & w2 and rpm N for different loads

11. Reduce the load of the motor ,decrease the speed of the motor by decreasing armature

voltage of the motor keeping field supply at 220V DC ,Switch of the unit remove the

connections

12. Determine the torque T using the formula

13. Plot the graphs of T against Ia

14. Determine Motor torque constant KT=∆T/∆Ia

15. Using the meters deteremine La and Ra of the field using meters or use the values

provided by manufacturer.


OBSERVATIONS:

Sl. No. Ia (Amps) N (rpm) W1 (kg) W2 (kg) T=( W1 -W2)6.5X9.81

(N – cm)

Torque = R S ~ S 9.81 21 (N – m)

(d) GRAPH:


TO DETERMINE KB:


PROCEDURE:

1. Keep all the knobs at minimum position

2. Connect 3 pin power cords to mains supply

3. Connect motor field to 220V DC fixed power supply

4. Connect armature of the motor to 220V variable Power supply

5. Connect 230V AC to the MCB input of the unit at front panel from AC mains

externally (use isolation transformer)

6. Keep armature control knob of the motor at minimum position

7. Switch AC mains supply

8. Now slowly vary the armature supply knob and note down the Ia,N and V for a suitable

weights.

9. Reduce the load of the motor,Decrease the speed of the motor by decreasing armature

voltage of the motor keeping field supply at 220v DC.Switch off the unit,remove the

connections.

10. Determine back emf Eb and speed ω using the formulae.

11. Plot the graphs of Eb against ω

12. Determine motor torque constant Kb ==∆ Eb /∆ ω


OBSERVATIONS:

Sl. No. Ia (Amps) N (rpm) V (Volts) Eb= V-IaRa

(Volts)

ω(rad/sec)

w = [(2x π x N) / 60]

(d) GRAPH:

TRANSFER FUNCTION OF MOTOR = KT / [ s ( Ra + sLa) (sJ + B) + KT x KB]

RESULT:


VIVA QUESTIONS:

1. Define Transfer function

a. It is deined as the ratio of laplace transform of the system response to the laplace

transform of the system input function..

2. What is the working principle of D.C. motor.

a. Whenever a current carrying conductor placed in a magnetic field it experiences a

force.

3. What is the use of Transfer function.

a. By having the transfer function one can find the output of a system for a given input. It

has the main application in the study of steady state as well as transient behavior of

systems

4. what are the applications of D.C.motors.

a. For paper machines, diesel-electric propulsion of ships, steel rolling mills shunt motors

are used. Series motors are used in electric traction, hoists,cranes, trollycars. Etc..........

5. When a D.C. motor produces maximum power output?

a. When back emf Eb equals half the applied voltage then D.C motor produces maximum

power output.


5. TRANSFER FUNCTION OF DC GENERATOR

AIM: To determine the transfer function of DC generator.

APPARATUS:

4. DC motor and DC generator set – 0.5HP/180V/1500 rpm

5. Controller unit suitable for the above motor and generator set to vary the armature

voltage and field voltage with Digital meters.

SPECIFICATIONS OF MOTOR & GENERATOR:

Armature Resistance = Ra =12 Ω

Armature Inductance = La = 135mH

Field Resistance = Rf = 550 Ω

Field Inductance = Lf = 21 H

Moment of Inertia = J = 0.024 Kg – m2

Friction Coefficient = B = 0.8

CIRCUIT DIAGRAM:


PROCEDURE:


2. The fixed DC supply of 220V is applied to the motor field winding.

3. The variable DC supply (0 – 220V) is connected to the motor armature winding.

4. The variable DC supply (100 – 200V) is connected to the generator field winding.

5. Switch on the MCB keeping armature voltage control Pot at its minimum position

& ON/OFF switch at OFF position and also variable field voltage pot at its

maximum position.

6. Now switch ON the armature control switch and vary the armature control

potentiometer till the motor rotates at its rated speed.

7. Note down If and Eg and enter in the tabular coloumn

8. Now vary the generator field supply and note down Eg for different If and entered

in the tabular coloumn.

9. 9.Draw the graph of Eg & If

OBSERVATIONS:

Sl. No. If (Amps) Eg (Volts)


GRAPH:

TRANSFER FUNCTION OF GENERATOR = ff sLR

Kg

RESULT:

VIVA QUESTIONS:

1. What is the principle of working of D.C. generator.

a. It works on the principle of the production of dynamically induced e.m.f . i.e,

whenever flux is cut by the conductor, dynamically induced e.m.f is produced in it

according to the law of electromagnetic induction

2. What are the different types of D.C machines?

a. 1) Seperately excited

2) Self excited -- a) series b) shunt c) compound -- (i) cumulatively compound (ii)

differentially compound

3. What are the applications of D.C GENERATORS?

a. Shunt generators are used for light and power supply purposes, charging of batteries.

Differential compound generator are used in are welding. Series generators are used in

boosters.


6. TEMPERATURE CONTROLLER USING PID

AIM: To study the performance of Temperature controller using PID.

APPARATUS: Temperature controller kit, Patch chords.

THEORY:

Temperature controller is one of the most commonly used control systems in

industrial operation. This system is designed to study about PID controller from

disturbances and uncertainties of plant prevalent in an actual process. The plant to be

controlled is a specially designed oven having a short heating as well as cooling time. A

solid state temperature sensor is used to convert the absolute temperature information to a

proportional electrical signal. The reference and actual temperature are indicated in

degree Celsius on a switch selectable digital display. The controller unit compares the

reference and the measured signals to generate the error with two hysteresis setting.


CIRCUIT DIAGRAM:

PROCEDURE:

1. Connect the temperature sensor from oven to the socket provided at the

PID controller.

2. Connect the oven to the socket provided at the PID connector.

3. Switch on the power supply to PID unit

4. Set the required temperature (SV) say 50 degree C using potentiometer. This is

displayed in digital temperature indicator by selecting the toggle switch to SET

position near temperature indicator (LED display).

5. Keep the P switch at ON,I &D switches at OFF positions. Keep gain at maximum

position it takes more time to attain the process temperature to minimum position

to set temperature.

6. Switch on input AC to the Thyristor(TRIAC)&Oven circuit.


7. Switch On the fan

8. Record the temperature of the oven by selecting the toggle switch at RUN

position for every 0.5 minute till the system reach steady state

9. Coll the system till 40 deg C by switching OFF AC ON switch provided

10. Do the experiment for P+I,P+D,P+I+D controller individually

11. Plot the graph of time versus temperatue.

OBSERVATIONS:

P alone is ON

P gain is max

P +I are ON

P gain is max

I gain below max

P +D are ON

P gain is max

D gain is max

P +I+D are ON

P,I,D gains area at

max

Time in

Min

Run

temp in

C

Time in

Min

Run

temp in

C

Time in

Min

Run

temp in

C

Time in

Min

Run

temp in

C

RESULT:


VIVA QUESTIONS:

1. What is the effect of P controller?

a. The proportional controller improves the stead state tracking accuracy, disturbance

signal rejection and relative stability.

2. What is the effect of PI controller?

a. The PI controller reduces the stead state error.

3. What is the effect of PD controller?

a. PD controller increases the damping of the system which results in reducing the peak

over shout.

4. What is the effect of PID controller?

a. The PID controller has the combined effect of all the three control actions.


7. CHARACTERISTICS OF MAGNETIC AMPLIFIER

AIM: To determine characteristics of Magnetic Amplifier.

APPARATUS: Magnetic Amplifier Kit, CRO, Patch Chords.

THEORY:

Magnetic Amplifier is a device consisting of combination of saturable reactors,

rectifiers and conventional transformers, used to secure control or amplification. In

magnetic amplifiers, the load current in the circuit is controlled by a D.C. magnetizing

current, which is comparatively very low as compared with load current. A large current

value is controlled by a small current value hence such types of circuits are termed as

current amplifiers. To control the load current, a saturable reactor is used. The reactance

of the reactor depends upon magnetic coupling and magnetism induced depends upon the

D.C. control current. This load current is controlled by using magnetic property and

hence the term magnetic amplifier.

The most common basic saturable reactor (Which is used in magnetic amplifier

circuits) consists of a three legged closed laminated core with coils wound on each leg.

The coil wound on central limb is called as control winding and coils wound on outer

limbs are called as load winding. Due to D. C. current in the control winding, the degree

of magnetization in the core is changed. An increase in control current, increase the flux

density until core saturation is approached. After this change in flux density will not be

applicable. Hence one can change the flux density, i.e. reactance of the core by changing

the D.C. current in the control winding.



PROCEDURE:

1. Make the connections as shown in the circuit

2.Keeping the DC supply at the minimum position switch on the unit

3.Now slowly increase the CW Dc supply/Rc in steps and note the control current Ic and

load current IL.

4.Plot the graph of load current IL against control current Ic.

(c) OBSERVATIONS:

Sl. No Control current in mA Load current In mA

a) CIRCUIT DIAGRAM

(b) PROCEDURE:




load current IL.



(c) OBSERVATIONS:


a) CIRCUIT DIAGRAM

(b) PROCEDURE:




load current IL.



(c) OBSERVATIONS:


(d) GRAPHS:

:


RESULT:.

VIVA QUESTIONS:

1.What are the drawbacks of magnetic amplifier?

a. Limited frequency response, much lower input impedance and finite power gain

2. What is the use of magnetic amplifier?

a. The magnetic amplifier is used to amplify the power.

3. Which feed back is used in magnetic amplifier for power amplification

a. Negative feedback

4. what are the advantages of magnetic amplifier.

a. Mechanically steady and inherently shock proof, low cost, compactness and lighter

weight and more flexibility.


8. CHARACTERISTICS OF AC SERVO MOTOR

AIM: To determine torque-speed characteristics of AC servo Motor.

APPARATUS: AC Servo Motor Kit, Patch Chords, Multimeter.

THEORY:

AC servo motors are two phase induction motors except for certain special design

features. The motor consists of two stators with distributed windings displaced 90

electrical degrees apart. In accordance with the usage, the two phase of such a motor are

termed reference and control phase. The voltages applied to windings are not balanced.

Generally voltages of 90 degrees phase difference is applied to each stator phases. In

normal mode of operation a fixed voltage is impressed on reference phase and variable

voltage is impressed on control phase. Both the control winding and reference winding

are similar and we can interchange them. The rotor of the AC servomotor is built with

high resistance, so that its X/R (Inductive reactance/Resistance) ratio is small which

results in linear speed-torque characteristics.

The advantages of AC servo motors are compact size, high torque, variable speed,

easy maintenance and long life. The servo motors are best suited for low power

applications. The output power of the AC servo motor usually varies from fraction of a

watt up to only to a few hundred watts.


CIRCUIT DIAGRAM:

PROCEDURE:

1. Connections are made as shown in circuit diagram.

2. The potentiometer P1 knob and control winding voltage knob are kept in minimum

position.

3. Switch on the main supply servo POWER Switch

4. The control winding voltage AC and reference winding voltage are measured by

multimeter. Adjust control winding voltage Wc by control knob to 220V.

5.Now slowly load the motor by switching ON SW & by varying P1 in steps of Ia. Now

note down the back emf Eb and rpm

6.Tabulate the readings in the table

7.Potentiometer P1 is brought back to minimum position & switch of the SW switch

8.Set the control winding voltage P2 to new value(say 210 or 200V)

9. Repeat step 5 & 6

10.Plot the graphs of speed Vs torque for two control winding voltages.

Note:If the control winding voltage is reduced(less than 190V) the motor may not rotate

due to insufficient voltage.

OBSERVATIONS:


Reference winding voltage Vr =

Control winding voltage =

Sl. No. Ia (Amps) Eb (Volts) N (rpm) P (watts) T (N-m)

Power P = Eb X Ia where Eb is back emf and Ia is armature current

Torque T = (P X 60) / (2 X Π X N) where N is speed.

RESULT:

VIVA QUESTIONS:

1 . What is servo motor.

a. The motors used in automatic control system or in servomechanism are called

servomotors.

2. what are the characteristics of servo motors.

a. 1) linear relationship between speed and electric control signal

2) Steady state stability 3) Fast response 4) Low inertia

3. What are the different types of rotors that are used in a.c. servomotor?

a. Squirrel case rotor and Drag –cut rotor

4. Write the differential equation governing A.C . Servomotor

a. Tm = K1Ec-K2 dθ /dt


9. LAG AND LEAD COMPENSATION

AIM: To study the Lag, Lead, Lag& Lead Compensators.

APPARATUS:

1. Lag-Lead Compensator Kit

2. Function Generator.

3. Patch Chords.

THEORY:

An additional device inserted in the system to modify its performance is called

Compensator. If the Compensator placed in series with the plant then it is called Series

Compensator. Among the so many Compensators they are widely classified as Lag, Lead,

Lag- Lead Compensator.

Lead Compensator increases band width and speeds up the response and

decreases the maximum overshoot in step response.

Lag Compensator increases the low frequency and again this improves the Steady

State accuracy of the system but decreases the speed of response due to band width.

If the improvements in both Transient and Steady State are required then Lag –

Lead compensator is used.


CIRCUIT DIAGRAM:


PROCEDURE: 1. Make the connections as shown in fig 1.

2. Select the components of required compensator circuit

3. Switch on the supply.

4. Adjust the amplitude of the signal generator to suitable voltage(max)

5. Take the phase angle between input & output waveforms using phase angle meter

for the frequency from 100Hz to 1KHz(Max 5KHz) in steps.

6. Enter the readings in the table provided.

7. Plot a graph of phase angle Vs frerquency &gain Vs frequency

8. Do the experiment for different compensator circuit.

TABULATIONS: LAG COMPENSATOR

S.No Frequency Input voltage

Vin

Output

voltage VO Gain(VO/Vin)

Phase Angle in

degrees


TABULATIONS: LEAD COMPENSATOR

S.No Frequency Input

voltage Vin

Output


Phase Angle in

degrees

TABULATIONS: LAG &LEAD COMPENSATOR

S.No Frequency Input

voltage Vin

Output


Phase Angle in

degrees


RESULT:

VIVA QUESTIONS:

1.What is compensation?

a. It is the design procedure in which the system behavior is altered to meet the desired

specifications, by introducing additional device called compensator

2. What are the different types of compensators?

a. Lag, lead and Lag-Lead compensator

3. Where the types of compensation schemes?

a. Series compensation and parallel or feedback compensation.

4. What is the user of compensation?

a. It stabilizer the unstable system and it provides desired performance

5. What is the effect of lag- compensator.

a. It improves the steady state performance, reduces band width and increases the rise

time.


10. CHARACTERISTICS OF DC SERVO MOTOR

AIM :To obtain speed torque characteristics of Dc servomotor

APPRATUS :Dc servo motor kit,Patch cards, multimeter.

CIRCUIT DIAGRAM:

PROCEDURE:

1.Connect the motor to corresponding terminals

2.Connect the speed se3nsor to the socket provided

3.Switch on the power supply

4.Keep the motor voltage to 10V

5.Now slowly load the motor.Do the experiment for different loads in steps of 50gms to

250gms

6.At each loading enter the current I,speed N,weight W in the table & determine the

torque

7.Experiment may be repeated for 9V,8V.

8.Reduce the DC servomotor voltage to minimum and switched off the unit

10.Plot the graphs of speed Vs torque for different motor voltages.


OBSERVATIONS:

Sl.No. V(volts) I amps N rpm W weight T gms-cm

Note: One disc weight =50 gms

Torque=KXWXr gms-cm

Let K=1=constant

Torque=W X r gms-cm

r = radius of the pulley in Cms.

GRAPH:


RESULT:

lab manual control systems lab - vsm.edu.in

Documents