Download - EE 2208 Lab Manual
-
7/27/2019 EE 2208 Lab Manual
1/50
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
EE 2208 MEASUREMENTS AND INSTRUMENTATION LABORATORY
LIST OF EXPERIMENTS
Sl. No. EXPERIMENT NAME
1. Study of DC Bridges (Wheatstone Bridge and Kelvins Double Bridge)
2. Study of Schering Bridge
3. Calibration of Single Phase Energy Meter
4. Calibration of Current Transformer
5. Measurement of Three Phase Power and Power factor
6. Digital to Analog Converter
7. Analog to Digital Converter
8. Calibration of Three Phase Energy Meter
9. Study of Pressure Transducer
10. Study of Displacement transducer.
11. Transient Response Of Series RC Circuit For DC Input
12. Instrumentation Amplifier.
STAFF IN CHARGE H.O.D / EEE
-
7/27/2019 EE 2208 Lab Manual
2/50
1
STUDY OF DC BRIDGES
A. STUDY OF WHEATSTONE BRIDGE
AIM:
To measure the unknown value of resistance of a resistor by using Wheatstone
bridge.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPARATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1. Known resistances100, 10
DRB-
2 (each)
1
2. Unknown resistances - - 1
3. Bread Board - - 1
4. Galvanometer 30-0-30 Analog 1
5. RPS (0-30V) Analog 1
6. Connecting Wires - - 1
FORMULA USED:
Rx= (R1 * R3) / R2 ()
Where, R3 Variable Resistance ()
R1 & R2 Known Resistance ()
Rx Unknown Resistance ()
THEORY:
The DC bridges are used to measure the resistance while the ac bridges are used to
measure the impedances consisting capacitances and inductances. The two types of DC bridges
are 1.Wheatstone Bridge 2. Kelvin Double Bridge.
-
7/27/2019 EE 2208 Lab Manual
3/50
2
CIRCUIT DIAGRAM:
Wheatstone Bridge B
R1 =10 R2=100
A C
RX R3
D
+ -
(0 30 V)
RPS
TABULATION:
Sl.No. Supply Voltage(V)
R3 () R x = (R3 * R1)/ R2 ()
D
-
7/27/2019 EE 2208 Lab Manual
4/50
3
The Wheatstone bridge consists of four resistance arms together with a source of e.m.f and a null
detector. The galvanometer is used as a null detector. The arms consisting of the resistances R1 &
R2 are called Ratio arms. The arm consisting of the resistor R4 is the unknown resistance value to
be measured. The battery is connected between A and C while galvanometer is connected
between B and D.
PROCEDURE:
1. From the available standard resistances, select a suitable value for the arms R1 & R2.
2. Select the suitable value for the resistance as R3.
3. Make the connections as per the circuit diagram.
4. Switch on the supply.
5. Adjust the value of DRB for null deflection in the galvanometer detector.
6. Increase the DC supply voltage continuously in steps and for each setting, obtain null
deflection.
DISCUSSION QUESTIONS:
1. What is a DC Bridge?
2. What are the types of DC bridges?
3. What are the applications of Wheatstone bridge?
RESULT:
Thus the measurement of unknown resistances using Wheatstone bridge was performed.
The values of unknown resistances are
-
7/27/2019 EE 2208 Lab Manual
5/50
4
-
7/27/2019 EE 2208 Lab Manual
6/50
5
B. STUDY OF KELVINS DOUBLE BRIDGE
AIM:
To measure the value of unknown resistance using Kelvin bridge.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements,
S.K.Kataria & sons, Delhi, 2003
APPARATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1. Known resistances10, 100K
DRB-
2(each)
1
2. Unknown resistances - - 1
3. Bread Board - - 1
4. Galvanometer 30-0-30 Analog 1
5. RPS (0-30V) Analog 1
6. Connecting Wires - - Req.
FORMULA:
Rx= (P/Q) * S ()
Where, Q,P --- Upper bridge arm resistances()
S--- Variable Resistances ()
Rx--- Unknown Resistances ()
THEORY:
The bridge consists of another set of ratio arms hence called Double Bridge. The second set
of ratio arms in the resistances q & p with the help of these resistances the galvanometer is
connected to point 3. The galvanometer gives null indication when the potential of the terminal
-
7/27/2019 EE 2208 Lab Manual
7/50
6
KELVINS DOUBLE BRIDGE:
P = 10 Q = 100
p = 10 q = 100
RX DRB
S
RPS (0 30V)
TABULATION:
Sl.No. P
()
Q
()
S
()
RX Actual
()
RX = (P / Q) * S
()
G
-
7/27/2019 EE 2208 Lab Manual
8/50
7
3 is same as the potential of the terminal 4. The important condition is that the ratio of the
resistance of ratio arms must be same the ratio of the resistances of the second ratio arms. When
both the contacts are switched to select the proper value of standard resistance the voltage drop
between the ratio arm connection points is changed but the total resistance around the battery
circuit is unchanged. With this arrangement, any contact resistance can be placed in series with
the relatively high resistance values of the ratio arms. Due to this, the effect of the contact
resistance becomes negligibly small. The ratio of R1 & R2 ie., R1 & R2 selected in such a way that
the larger part of the variable standard resistance is used and Rx is determined.
PROCEDURE:
1. Connections are given as per the circuit diagram.
2. Supply is switched ON.
3. Galvanometer is connected in the deflector (mentioned) terminal and the zero
deflection value is obtained by varying the value of potentiometer.
4. The value of Rx is calculated by using the formula.
DISCUSSION QUESTIONS:
1. What is Kelvins double bridge?
2. What are the advantages of bridge circuits?
3. State the main differences between AC and DC bridges?
RESULT:
Thus the unknown value of resistance was measured by using Kelvins Double Bridge.
The unknown values of resistances are
-
7/27/2019 EE 2208 Lab Manual
9/50
8
-
7/27/2019 EE 2208 Lab Manual
10/50
9
STUDY OF SCHERING BRIDGE
AIM:
To measure the unknown value of capacitance of a capacitor by using Schering
Bridge.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPARATUS REQUIRED:Sl.No. Name of the Equipment Range Type Quantity
1. Known capacitance 0.1 F - 1
2. Unknown capacitance - Box 1
3. Bread Board - - 1
4. Multimeter - Digital 1
5. AFO - Digital 16. Connecting Wires - - Required
FORMULA USED:
Cx= (R1 * C2) / Rm ()
Where, Rm Multiple Resistances ()
R1 Variable Resistance ()
CxUnknown Capacitance (F)
C2 Fixed Capacitance (F)
THEORY:
Schering Bridge is one of the most widely used AC Bridge for measurement
of unknown capacitance, dielectric losses and power factors. It can be used for low
voltages. The perfect capacitor Cx is to be measured. The Rx is series resistance C2 is
standard air capacitor having very stable value.R3 and R4 are non inductive resistance
where C4 is variable capacitor.
Cx=(R4 / R3) * C2 ; Cx=(R4 / R3) * C2
-
7/27/2019 EE 2208 Lab Manual
11/50
10
CIRCUIT DIAGRAM:
C1RM
R1 1M 100K 10K 1K 100 1
To Detector
C20.1F CX
TABULATION:
SL.NO.R1()
RM()
C2(F)
CX(F)
1.
2.
3.
4.
5.
DISCUSSION QUESTIONS:
1. What two conditions must be satisfied to make an AC bridge balance?
2. What is Schering Bridge?
3. What are the advantages of Schering Bridge?
-
7/27/2019 EE 2208 Lab Manual
12/50
11
PROCEDURE:
Set the potentiometer to the initial position as mentioned above.
Connect the unit to mains supply 220V AC through power cord.
Switch ON the unit. The neon lamp will glow indicating that the unit is ready for
operation.
Using patch cord feed the sine wave signal from the built-in oscillator to the bridge
circuit.
Connect the unknown capacitance , whose value is to be determined , across
sockets marked Cx
Connect a digital multimeter having a range of AC 0-200mV/0-2V across thesockets marked TO DETECTOR and GROUND
Using a patch cord , connect the topend of the bridge circuit to the multiplex
resistor (Rm) of value in the mid-range (like 1K )
Read the bridge output in the Digital multimeter.
Change the multiplex resistor to successive higher or lower values, such that the
unbalanced output drops towards zero
By selecting the appropriate value of Rm for minimum unbalance ,Vary the
resistance R1 to obtain the final balance point
Correct balancing is obtained when the output drops almost to zero
Disconnect all patch cords from the bridge circuit
Using a digital multimeter , measure R1
Substitute the values of Rm, R1,and C2 in the formula and evaluate the unknown
capacitance
RESULT:
Thus the unknown value of capacitance of a capacitor was measured using
Schering Bridge.
The unknown capacitance value of the Capacitor is ..
-
7/27/2019 EE 2208 Lab Manual
13/50
12
-
7/27/2019 EE 2208 Lab Manual
14/50
13
CALIBRATION OF CURRENT TRANSFORMER
AIM:
To study the working principle of current transformer and to calibrate the same.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRARATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1. Ammeter(0 10A)
(0 500mA)
MI
MI
1
1
2. Current transformer 200 / 5 A 1
3. Resistive load 3 kW Single phase 1
4. Voltmeter (0 300V) MI 1
5. Connecting wires Required
PRECAUTIONS:
The secondary of the current transformer should not be open circuited while
primary winding is energized.
FORMULA USED:
% ratio error = [(Nominal ratio Actual ratio) / Actual ratio] * 100
Nominal ratio = Rated primary current of CT / Rated secondary current of CT
Actual ratio = Primary current (reading) of CT / Secondary current (reading) of CT
THEORY:
The calibration is the procedure for determining the correct values of
measurand by comparing with the standard ones. The instrument with which comparison
-
7/27/2019 EE 2208 Lab Manual
15/50
14
CIRCUIT DIAGRAM:(0 10A) MI
10 A Current Transformer (200 / 5A)
P
D
P
S (0 300V) MI
T
S (0 500mA) MI
N
10 A 1 Variac
(0 230/270V)
TABULATION:
Sl.No.Primary Current
Ipy (A)
Secondary Current
Isy (mA)Nominal Ratio Actual Ratio % error
MODEL GRAPH:
Primary Current Secondary Current
A
V
L
O
A
D
230 V1 ,50Hz
Supply
A ResistiveLoad 3 KW
/ 230V
SecondaryCurrent
NominalRatio
-
7/27/2019 EE 2208 Lab Manual
16/50
15
is made is called as a standard instrument. The instrument which is unknown and it is
said to be calibrated is called test instrument .Thus in calibration; test instrument is
compared with the standard instrument. There are two fundamental methodologies for
obtaining the comparison between the test instrument and standard instrument. These
methodologies are
Direct Comparison
Indirect Comparison
PROCEDURE:
1. Circuit connections are given as per the circuit diagram
2. Supply is switched ON and by adjusting the Variac the rated voltage is set in the
voltmeter.
3. By increasing the load in steps, the primary current and secondary current
ammeter readings are noted.
DISCUSSION QUESTIONS:
1. What is calibration?
2. What are the different calibration methodologies?
3. What are the advantages of instrument transformers?
4. Give the main differences between CT and PT.
RESULT:
Thus the working principle of the Current Transformer was studied and
calibrated.
-
7/27/2019 EE 2208 Lab Manual
17/50
16
-
7/27/2019 EE 2208 Lab Manual
18/50
17
CALIBRATION OF SINGLE PHASE ENERGY METER
AIM:
To calibrate the single phase Energy meter by direct loading.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRARATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1. Ammeter (0 10A) MI 1
2. Voltmeter (0 300V) MI 1
3. Energy meter 10A/230V Analog 1
4. Stop watch Analog 1
5. Connecting wires Required
FORMULA USED:
Power= Voltage in Volts X Current in Amps
True Energy = Number of revolutions / Energy meter constant
Actual Energy = [(Power X Time taken for n revolutions) / (3600 X 1000)]
% of Absolute error = (Actual Energy True Energy / True Energy) X 100
THEORY:
The calibration is the procedure for determining the correct values of measurand by
comparing with the standard ones. The standard of device with which comparison is
made is called as a standard instrument. The standard instrument which is unknown and
it is said to be calibrated is called test instrument .Thus in calibration; test instrument is
compared with the standard instrument. There are two fundamental methodologies for
obtaining the comparison between the test instrument and standard instrument. These
methodologies are
-
7/27/2019 EE 2208 Lab Manual
19/50
18
CIRCUIT DIAGRAM:(0 10A) MI Energy Meter
10 A
P C1 C2
D P1 P2P
S (0 300V) MI
T
S
N
10 A 1 Variac
(0 230/270V)
TABULATION:
Sl.No.Voltage
(V)
Current
(A)
Power
(W)
Time
(Sec)
No. of
revolutions
Actual
Energy
True
Energy
%
error
A
V
L
O
A
D
230 V1 ,50Hz
SupplyResistive
Load 3 KW
/ 230V
-
7/27/2019 EE 2208 Lab Manual
20/50
19
Direct Comparison
Indirect Comparison
The calibration offers a guarantee to the device or instrument that is operating with
required accuracy under the stipulated environmental conditions. It creates the confidence
of using the properly calibrated instrument, in users mind. The periodic calibration of
instrument is very much necessary.
The calibration procedure involves the steps like visual inspection for various
defects, installations according to the specifications, zero adjustment, etc.
PROCEDURE:
1. Circuit connections are given as per the circuit diagram2. Supply is switched ON by closing the DPSTS.
3. By increasing the load in steps, the voltmeter, ammeter and wattmeter readings are
noted. Also the time taken for the energy meter disc to rotate for n revolutions is
noted down.
4. Using the formula the percentage error is calculated for each set of readings.
DISCUSSION QUESTIONS:
1. What is creeping?
2. Which torque is absent in energy meter? Why?
3. Define energy meter constant.
RESULT:
Thus the calibration of the single phase Energy meter was done and the Absolute
error was calculated.
-
7/27/2019 EE 2208 Lab Manual
21/50
20
CIRCUIT DIAGRAM: RESISTIVE LOAD
R 10 A
(0 -10A) MI 600V, 10A, UPF
T M L
P C V
415V R
3 S (0 600V) MI
Y 10 A LOAD50 Hz
SUPPLY
T
S Y
B10 A
B C V
M L
600V, 10A, UPF
3 Variac
TABULATION:
M.F.. M.F.
Sl.No.
VL
(V)
IL
(A)
W1 W2 Total
Power
W1 + W2
Watts
Phase angle
Power
factor
Cos
Observed
Reading
Actual
Reading
Observed
Reading
Actual
Reading
M.F. Multiplication Factor
A
V
-
7/27/2019 EE 2208 Lab Manual
22/50
21
MEASUREMENT OF THREE PHASE POWER AND POWER FACTOR
AIM:
To measure the 3 phase power using two single element wattmeter with 3 phase
resistive and inductive load.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRARATUS REQUIRED:
S.No. Name of the Equipment Range Type Quantity
1. Ammeter (0 10A) MI 1
2. Voltmeter (0 600V) MI 1
3. Wattmeter( 150 / 300 / 600V)
(5 / 10A)
Single element
UPF1
4. Connecting wires Required
FORMULA USED:
Phase angle, = tan- 1 3 [Higher reading lower reading]
[Higher reading + lower reading]
Total Power = W1 + W2 (watts)
Power factor = Cos
THEORY:
Three phase power measurements can be done by the following methods,
i. By using three phase wattmeter.
ii. By using 3-single element wattmeter i.e., three wattmeter method.
iii. By using 2-single element wattmeter i.e., two wattmeter method.
iv. By using 1-single element wattmeter i.e., one wattmeter method.
-
7/27/2019 EE 2208 Lab Manual
23/50
22
CIRCUIT DIAGRAM: INDUCTIVE LOAD
R 5 A
(0 -5A) MI 600V, 5A, UPF
T M L
P C V415V A1 C2
3 S (0 600V) MI
Y 5 A50 Hz
SUPPLY B1 A2
T
S
5 A C1 B2
B C V
M L 3Phase
600V, 5A, UPF Induction Motor
3 Variac
TABULATION:
M.F.. M.F.
Sl.No.
VL
(V)
IL
(A)
W1 W2 Total
Power
W1 + W2
Watts
Phase angle
Power
factor
Cos
Observed
Reading
Actual
Reading
Observed
Reading
Actual
Reading
M.F. Multiplication Factor
A
V
-
7/27/2019 EE 2208 Lab Manual
24/50
23
Among the above four methods, the most commonly used three phase power
measurement techniques are, two wattmeter method and three wattmeter method.
PROCEDURE:
1. Circuit connections are given as per the circuit diagram
2. Supply is switched ON by closing the TPSTS.
3. By adjusting the Variac rated voltage is set in the voltmeter.
4. By switching ON the load (resistive / inductive) and increasing the load in steps,
the voltmeter, ammeter and wattmeter readings are noted.
5. Using the formula the power factor is calculated.
DISCUSSION QUESTIONS:
1. Define power factor.
2. Explain why it is necessary to potential coil circuit purely resistive in wattmeters?
3. Give the expression for 3phase power.
4. What is LPF Wattmeter?
RESULT:
Thus the 3 phase power was measured by using two single element wattmetersand the power factor was calculated.
-
7/27/2019 EE 2208 Lab Manual
25/50
24
CIRCUIT DIAGRAM:
(+5V)
MSB
LSB
B0 B1 B2 B3 B4 B5 B6 B7
20 K 20 K 20 K 20 K 20 K 20 K 20 K 20 K
10 K 10 K 10 K 10 K 10 K 10 K 10 K 20 K
20 K
47 K
10 K 7
2 47 K 7
6 2
3 6 Vo
3
4
TABULATION:
DIGITAL INPUT ANALOG OUTPUT
(V)LSB MSBB7 B6 B5 B4 B3 B2 B1 B0 Practical Theoretical
-
7/27/2019 EE 2208 Lab Manual
26/50
25
DIGITAL TO ANALOG CONVERTER
AIM:
To convert the given digital signal input to analog output.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRARATUS REQUIRED:
S.No. Name of the Equipment Range Type Quantity
1. Digital to Analog Converter Kit - - 1
2. Patch cards - - Required
FORMULA USED:
V0 = VR x RF / Rin{ Bo /2 + B1 /4 + B2 /8 + B3 /16 + B4 /32 + B5 /64 + B6 /128 + B7 /256 } Volts
PROCEDURE:
1. Circuit connections are given as per the circuit diagram
2. Supply is switched ON. By adjusting RPS V1 values are set and corresponding
output voltage V0 are noted down.
3. Using the formula the gain is calculated.
DISCUSSION QUESTIONS:
1. What are the different methods of D/A Conversion?
2. What are LSB and MSB?
3. Give the pin specifications of IC 741.
RESULT:
Thus the performance of the D/A converter was studied.
-
7/27/2019 EE 2208 Lab Manual
27/50
26
-
7/27/2019 EE 2208 Lab Manual
28/50
27
ANALOG TO DIGITAL CONVERTER
AIM:
To convert the given analog signal input to digital output.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPARARATUS REQUIRED:
S.No. Name of the Equipment Range Type Quantity
1. Analog to Digital Converter Kit - - 1
2. Patch cards - - Required
PROCEDURE:
1. Circuit connections are given as per the circuit diagram.
2. Supply is switched ON. For different values of analog input the corresponding
digital output values are noted down.
3. The digital output values are tabulated.
DISCUSSION QUESTIONS:
1. What are the different methods of A/D conversion?
2. What is IC 7408?
3. What is a clock signal?
-
7/27/2019 EE 2208 Lab Manual
29/50
28
TABULATION:
ANALOG INPUT (V)
DIGITAL OUTPUT
MSB LSB
B6 B5 B4 B3 B2 B1 B0
ANALOG VOLTAGE (V) INCREMENT CALCULATION
-
7/27/2019 EE 2208 Lab Manual
30/50
29
RESULT:
Thus the performance of the instrumentation amplifier is studied and gain is
calculated.
-
7/27/2019 EE 2208 Lab Manual
31/50
30
CIRCUIT DIAGRAM:
-
7/27/2019 EE 2208 Lab Manual
32/50
31
CALIBRATION OF 3 PHASE ENERGY METER
AIM:
To calibrate the 3 phase Energy meter by direct loading.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRARATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1. Ammeter (0 10A) MI 1
2. Voltmeter (0 600V) MI 1
3. Energy meter 3 1
4. Stop watch Analog 1
5. Connecting wires Required
FORMULA USED:
Power = Wattmeter reading x Multiplication Factor(M.F)
True Energy = Number of revolutions / Energy meter constant
Actual Energy = [(Power X Time taken for n revolutions) / (3600 X 1000)]
% of Absolute error = (Actual Energy True Energy / True Energy) X 100
THEORY:
Energy is the total power delivered and consumed over a time interval by
an electrical system.
Energy=Power * Time
Electrical energy is expressed as
W= VIt Kwh
V is expressed in volts,
I is expressed in ampere and t is in seconds
-
7/27/2019 EE 2208 Lab Manual
33/50
32
TABULATION:
Multiplication Factor:.. Energy meter constant=
Sl.No.
Voltage
(V)
Current
(A)
Wattmeter
Reading
Time
(Sec)
Number of
revolutions
Actual
Energy
True
Energy
%
error
Observed Actual
MODEL GRAPH:
%Error
Current
-
7/27/2019 EE 2208 Lab Manual
34/50
33
Unit for energy is joules or watt second. If the unit of time is taken as hour, energy is then
expressed in watt hours, for larger units: energy may be expressed in kilo Watt Hour
PROCEDURE:
1. Circuit connections are given as per the circuit diagram
2. TPSTS is closed and the load is applied gradually.
3. Voltmeter, Ammeter and wattmeter readings and time taken for energy meter disc
to rotate n revolutions are noted.
4. Percentage error is calculated for various load currents.
RESULT:
Thus the calibration of the 3 Energy meter was done and the Absolute error was
calculated.
-
7/27/2019 EE 2208 Lab Manual
35/50
34
CIRCUIT DIAGRAM:
7 (+Vcc)
2
6
3
4 (-Vcc)
Differential Amplifier Mircro Controller Output
(Op-Amp) (Calibration) (LED Display)
+
-
Strain Gauge
TABULATION:
Increasing Pressure
Sl.NO. APPLIED PRESSURE (Kg / Cm2) Output Voltage (mV)
Decreasing Pressure
Sl.NO. APPLIED PRESSURE (Kg / Cm2) Output Voltage (mV)
MODEL GRAPH: Vo (mV)
Decreasing Pressure Increasing pressure (Kg/ Cm2)
(Kg/ Cm2)
Pressure
DisplayMicroController
RAM EPROM
-
7/27/2019 EE 2208 Lab Manual
36/50
35
STUDY OF PRESSURE TRANSDUCER
AIM:
To study the performance characteristics of Pressure Transducer.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1.Pressure Transducer kit with
Foot pump- - 1
THEORY:
Pressure is the basically a physical parameter is defined as the force acting per
unit area measured at a given point or over a surface. Most pressure measuring devices
use plastic members for sensing pressure at primary stage. These elastic members convert
the pressure into mechanical displacement which is later converted into electrical form
using a secondary transducer. The principle of working of these devices can be explained
as, the fluid or gas whose pressure is measured is made to press the pressure sensitive
element and since the element is a elastic member it deflects causing a mechanical
displacement. The displacement is proportional to the pressure applied. The
displacement is then measured with a help of electrical transducer is proportional to the
displacement and hence to the applied input pressure. The commonly used pressure
sensitive devices are
Diaphrams
Capsule
Bourdon tubes
Bellows
-
7/27/2019 EE 2208 Lab Manual
37/50
36
-
7/27/2019 EE 2208 Lab Manual
38/50
37
PROCEDURE:
1. 230 V AC Main Supply is switched ON.
2. By pressuring the pump, Pressure into the air cylinder is increased.
3. The pressure and output voltage in the front panel of the trainer kit is noted.
4. The pressure from the air cylinder is decreased in steps and the values of
pressure and voltage are tabulated.
DISCUSSION QUESTIONS:
1. How the transducers are classified?
2. Give the factors to be considered in selecting a transducer?
3. What is an active transducer?4. What is a passive transducer?
RESULT:
Thus the characteristics of Pressure Transducer were studied and the readings are
tabulated.
-
7/27/2019 EE 2208 Lab Manual
39/50
38
CIRCUIT DIAGRAM:
A.C. Input
Primary of the transformer
Displacement
Secondary of the transformer
Es1 Es2
VO
TABULATION:
Positive Displacement
Sl.No. MSR VSCTR = MSR +VSC
x errorSensor Output (mV) Sensor Displacement (mm)
Negative Displacement
Sl.No. MSR VSCTR = MSR +VSC
x errorSensor Output (mV) Sensor Displacement (mm)
MODEL GRAPH: Sensor Output (mV)
Negative Displacement Positive Displacement
Displacement (mm)
CORE
-
7/27/2019 EE 2208 Lab Manual
40/50
39
SYUDY OF DISPLACEMENT TRANSDUCER
AIM:
To study and determine the performance characteristics of LVDT.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity2. LVDT kit - - 1
THEORY:
The most widely used inductive transducer to translate the linear motion into electrical
signals is the linear variable differential transformer(LVDT).LVDT is a differential transformer
consisting of a single primary winding P and two secondary windings S1 and S2 wound over a
hollow bobbin of non-magnetic and insulating material. The secondary windings S1 and S2 have
equal number of turns and are identically placed on either side of the primary winding. A
movable soft iron core is placed inside the transformer. The displacement to be measured is
applied to the soft iron core. In order to overcome the problem of eddy current losses in the core,
nickel-iron alloy is used as core material and is slotted longitudinally.
Primary winding is connected to an AC source of voltage varying from 5 to 25V and of
frequency ranging from 50Hz to 20kHz.Since the primary winding is excited by an alternating
current source, it produces an alternating magnetic field which in turn induces alternating
voltages. The output voltages of secondary winding S1 and ES1 and that of secondary winding S2
is ES2.Inorder to convert the output voltage from S1 and S2 into a single voltage signal, the two
secondaries S1 and S2 are connected in series opposition as shown in figure. Therefore the output
voltage of the transducer is the difference of the two voltages.
Differential output voltage E0=Es1-Es2
-
7/27/2019 EE 2208 Lab Manual
41/50
40
-
7/27/2019 EE 2208 Lab Manual
42/50
41
When the core is at its normal (NULL) position, the flux linking with both he secondary
windings are equal and hence equal emfs are induced in them. Thus at null position Es1=Es2.Since
the output voltage of the transducer is the difference of the two voltages, the output voltage E0 is
zero at null position. Now if the core is moved to the left of the NULL position, more flux links
with winding S1 and Less wit winding S2.Hence output voltage Es1,of the secondary winding
S1,is more than Es2,the output voltage of secondary winding S2,The magnitude of output voltage
is,thus,E0=Es1-Es2 and the output voltage is in phase with the primary voltage. Similarly, if the
core is moved to the right of the null position,the flux linking with winding S2 becomes larger
than that linking with winding S1.Hence output voltage Es2 of the secondary winding is more
than Es1,the output voltage of the secondary winding S1.The magnitude of output voltage is thus
,E0=Es2-Es1 and is 180 out of phase with the primary voltage. Thus the LVDT output voltage is a
function of the core position. The amount of voltage change in either secondary winding is
proportional to the amount of movement of core. Hence, we have an indication of amount of
linear motion. By noting which output voltage is increasing or decreasing, we can determine the
direction of motion .Any physical displacement of the core causes the voltage of one secondary
winding to increase while simultaneously reducing the voltage in the order secondary winding.
The amount of output voltage may be measured to determine the displacement
PROCEDURE:
1. Circuit connection is given as per the circuit diagram.
2. The core is slowly moved and the displacement value and output voltage is noted
down.
DISCUSSION QUESTIONS:
1. What is a transducer?
2. Mention some advantages of LVDT.
3. List out the disadvantages of LVDT.
4. Mention the applications of LVDT.
RESULT:
Thus the characteristic of displacement Transducer was studied and the graph was
drawn.
-
7/27/2019 EE 2208 Lab Manual
43/50
42
CIRCUIT DIAGRAM:
(0-25mA)MC
10K + -
(0-30V)MC
+
RPS (0-30V) +
DPSTS C
4700 F-
TABULATION:
Sl.No. CHARGING DISCHARGING
V(volts) T(sec) V(volts) T(sec)
A
V
-
7/27/2019 EE 2208 Lab Manual
44/50
43
TRANSIENT RESPONSE OF SERIES RC CIRCUIT FOR DC INPUT
AIM:
To obtain transient response of RC circuit for DC input.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRARATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1. Resistors 10 K - 1
2. Capacitor 4700F - 1
3. RPS (0 30V) Analog 1
4. Ammeter (0-25mA) MC 1
5. Voltmeter (0-30V) MC 1
6. Bread Board - - 1
7. Stop watch - - 1
8. DPSTS - - 1
9. Connecting Wires - - Required
THEORY:
In series RC circuit shown in figure, the switch S is in open state initially. There is
no charge on the capacitor and no voltage across it. At the instant t=0, switch S is closed.
Immediately after closing the switch, the capacitor acts as a short circuit path, so current
at the time of switching is high. The voltage across the capacitor is zero at t=0 as the
capacitor acts as a short circuit, the current is maximum and is given by
I=V/R amperes.
This current is maximum at t=0+ which is called charging current. As the capacitor
starts charging, the voltage across capacitor Vc starts decreasing. After some time, when
-
7/27/2019 EE 2208 Lab Manual
45/50
44
MODEL GRAPH:
Capacitor charging capacitor Discharging
-
7/27/2019 EE 2208 Lab Manual
46/50
45
the capacitor charges to V volts, it achieves steady state. In steady state, it acts as an open
circuit, so the current will be zero finally.
Transient current, i= [V/R] X [et / RC]
So at time t=0, i=V/R is maximum and in steady state it becomes zero.
PROCEDURE:
1. Circuit connections are given as per the circuit diagram
2. Supply is switched ON and capacitor is charges to its rated voltage in steps with a
time interval.
3. The corresponding voltmeter readings and time interval are noted down.
4. By discharging the capacitor from its rated voltage, in same steps the voltmeterreadings and time intervals are noted down.
5. Graphs are plotted for charging and discharging of capacitor separately.
DISCUSSION QUESTIONS:
1. What is transient?
2. What is the time constant for RC series circuit?
3. Define transient time?
RESULT:
Thus the transient response of series RC circuit for DC input was obtained and the
graph was plotted.
-
7/27/2019 EE 2208 Lab Manual
47/50
46
CIRCUIT DIAGRAM:
+ VCC2 7 7 56 K
6
3
+ 12V 4 7
- VCC 12 K 2
6
3.9 K
Vo
1 K 1 K 12 K 3 4
0.4 K 56 K
1 K 1 K
3.9 K
7
2
6
34
TABULATION:
Sl. No.
Input Voltage
(mV)Output Voltage
(Vo)
Gain Ad = Vo /
Vin
Gain in dB = 20 log
(Ad)V1 V2
-
7/27/2019 EE 2208 Lab Manual
48/50
47
INSTRUMENTATION AMPLIFIER
AIM:
To construct and study the performance of instrumentation amplifier and to obtain
the gain.
REFERENCES:
1. A.K.Sawhney,A Course in Electrical & Electronics Measurements
& Instrumentation, Dhanpat Rai and Co, 2004
2. J.B.Gupta, A Course in Electronic and Electrical Measurements, S.K.Kataria
& sons, Delhi, 2003
APPRARATUS REQUIRED:
Sl.No. Name of the Equipment Range Type Quantity
1. Op amplifier IC 741 3
2. Resistors
1 K, 3.9 K,
0.4 K, 12 K,
56 K
- Each 2
3. RPS (0 30V) - 1
4. Bread Board - - 1
5. Connecting Wires - - Required
FORMULA USED:
V0 = { (V1 V2) x R2 / Rf [1 + (2R1 / Rg)] } Volts
Ad = (V0 / [V1 V2])
Theory:
Physical quantities like temperature, humidity. Light intensity, water flow etc., are
usually measured with the help of transducers. The output of transducer has to be
amplified, so that it can be drive the display system of control system. This function is
performed by an instrumentation amplifier. The important features of an instrumentation
amplifier are
-
7/27/2019 EE 2208 Lab Manual
49/50
48
-
7/27/2019 EE 2208 Lab Manual
50/50
High input impedance.
High gain accuracy
High CMRR
High gain stability with low temperature coefficient
Low output impedance
PROCEDURE:
1. Circuit connections are given as per the circuit diagram
2. Supply is switched ON. By adjusting RPS V1 values are set and corresponding
output voltage V0 are noted down.
3. Using the formula the gain is calculated.DISCUSSION QUESTIONS:
1. What is an instrumentation amplifier?
2. List the important characteristics of operational amplifier.
3. What are the applications of instrumentation amplifier?
4. What is CMRR?
RESULT: