Electrical Measurments Lab Manual
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Transcript of Electrical Measurments Lab Manual
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1
ELECTRICAL MEASURMENTS LAB
DEPARTMENT OF
ELECTRICAL AND ELECTRONICS ENGINEERING
ACADEMIC YEAR 2012-2013
IV B.Tech EEE I-SEMESTER
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PREFACE
The significance of the Electrical Measurements Lab is renowned in the various fields of
engineering applications. For an Electrical Engineer, it is obligatory to have the practical ideas
about the Electrical Measurements. By this perspective we have introduced a Laboratory manual
cum Observation for Electrical Measurements Lab.
The manual uses the plan, cogent and simple language to explain the fundamental aspects
of Electrical measurements in practical. The manual prepared very carefully with our level best.
It gives all the steps in executing an experiment.
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ACKNOWLEDGEMENT
It is one of lifes simple pleasures to say thank you for all the help that one has extended
their support. I wish to acknowledge and appreciate Assoc Prof K Ram Krishna, Assist. Prof.
R.Munishwar, Foreman. P Prabhu Dass, and A Ramesh for their sincere efforts made
towardsdeveloping the Electrical Measurements Lab manual. I wish to thank students for their
suggestionswhich are considered while preparing the lab manual.
I am extremely indebted to Sri.Col Dr. T. S. Surendra, Principal and Professor,
Department of Electrical and Electronics Engineering, BVRIT for his valuable inputs and sincere
support to complete the work.
Specifically, I am grateful to the Management for their constant advocacy and incitement.
Finally, I would again like to thank the entire faculty in the Department and those people
who directly or indirectly helped in successful completion of this work.
(Prof. N. BHOOPAL)
HOD - EEE
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GUIDELINES TO WRITE YOUR OBSERVATION BOOK
1. Experiment Title, Aim, Apparatus, Procedure should be on right side.
2. Circuit diagrams, Model graphs, Observations table, Calculations table should be left side.
3. Theoretical and model calculations can be any side as per your convenience.
4. Result should always be in the ending.
5. You all are advised to leave sufficient no of pages between experiments for theoretical or
model calculations purpose.
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DOS AND DONTS IN THE LAB
DOS:-
1. Proper dress has to be maintained while entering in the Lab. (Boys Tuck in and shoes, girls with apron)
2. All students should come to the Lab with necessary tools. (Cutting Pliers 6, Insulation remover and
phase tester)
3. Students should carry observation notes and record completed in all aspects.
4. Correct specifications of the equipment have to be mentioned in the circuit diagram.
5. Student should be aware of operating equipment.
6. Students should be at their concerned experiment table, unnecessary moment is restricted.
7. Student should follow the indent procedure to receive and deposit the equipment from the Lab Store
Room.
8. After completing the connections Students should verify the circuits by the Lab Instructor.
9. The reading must be shown to the Lecturer In-Charge for verification.
10. Students must ensure that all switches are in the OFF position, all the connections are removed.
11. All patch cords and stools should be placed at their original positions.
DONTs:-
1. Dont come late to the Lab.
2. Dont enter into the Lab with Golden rings, bracelets and bangles.
3. Dont make or remove the connections with power ON.
4. Dont switch ON the supply without verifying by the Staff Member.
5. Dont switch OFF the machine with load.
6. Dont leave the lab without the permission of the Lecturer In-Charge.
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JAWAHARLAL NEHRU TECHNOLOGICAL
UNIVERSITY HYDERABAD
IV Year B.Tech. EEE I-Semester L T/P/D C
0 -/3/- 2
(57602)ELECTRICAL MEASUREMENTS LAB
The following experiments are required to be conducted Compulsory experiments.
1. Calibration and testing of a 1- Energy meter
2. Calibration of Dynamometer Power Factor meter
3. Crompton D.C Potentiometer -Calibration of PMMC Ammeter and PMMC voltmeter
4. Kelvins Double Bridge - Measurement of Resistance Determination of Tolerance
5. Dielectric Oil Testing using H.T. testing Kit
6. Schering Bridge and Anderson Bridge
7. Measurement of 3- Reactive Power using 1- Wattmeter
8. Measurement of Parameters of a choke coil using 3 voltmeter and 3 ammeter methods.
In addition to the above experiments, at least any two of the experiments from the following list are
required to be conducted.
9. Calibration of L.P.F Watt Meter by Phantom testing
10. Measurement of 3- Power with single Watt meter and 2 Nos of C.T.
11. C.T. Testing using mutual Inductor Measurement of % ratio error and phase angle of given C.T
by Null method.
12. P.T. testing by comparison V.G as Null detector Measurement of % ratio error and phase
angle of given P.T.
13. LVDT and Capacitance pickup - characteristics and calibration.
14. Resistance strain gauge strain measurements and calibration.
15. Transformer terms ratio amusement using A.C. Bridge
16. Measurement of % Ratio error & phase Angle of given Current Transformer (C.T) by comparison.
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ELECTRICAL MEASUREMENTS LAB
EEE IVth
YEAR 1ST
SEMESTER Academic year 2012-2013
LIST OF EXPERIMENTS CONDECTED BY EEE DEPARTMENT:
S. No Name of the Experiment Page no 1 Calibration and testing of a 1- Energy meter
2 Calibration of Dynamometer Power Factor meter
3 Calibration of PMMC voltmeter using Crompton D.C Potentiometer
4 Measurement of Resistance using Kelvins Double Bridge
5 Testing of transformer Oil
6 Schering Bridge and Anderson Bridge
7 Measurement of 3- Reactive Power using 1- Wattmeter
8 Measurement of Parameters of a choke coil using 3 voltmeter and 3ammeter
Additional experiments
9 Calibration of L.P.F Watt Meter by Phantom testing
10 Measurement of % Ratio & phase Angle Error of A Current Transformer
11 Calibration of Domestic Applications
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100/5A
0-5A,MI
0-300V,MI
N
R
230V,1- AC
Supply,50Hz
Y
B
415V,3- AC
Supply,50Hz
A
5/10A, 300V, 1500W,UPF 5/10A, 300V, 1- Energy Meter
Circuit diagram: - Calibration of 1- Energy meter
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1. Calibration of 1- Energy meter
Aim:- To determine the error of a 1- Energy meter for different loadings & draw the % error Curve.
Apparatus:-
Theory:-
The construction varies in details form one manufacture product to the next how ever the
differences are vary minor in nature. There are four main parts of the operating mechanism.
1) Driving system.
2) Moving system .
3) Braking system.
4) Registry system.
A permanent magnet positioned near the edge of the aluminum disc from the braking system
the aluminum disc moves in the field of this magnet and there provide a breaking torque. The
positioned as explained earlier.
Procedure:-
1) Connect the circuit as show in circuit diagram.
2) Apply rated voltage to the pressure coil of energy meter.
3) Vary the current through the current coil in different steps by 1A,2A,3A using 1- variac.
4) Note down the time for 10 Revolutions of energy meter.
5) Note down the readings of voltmeter, Ammeter & wattmeter for different currents that is 1A,2A,3A etc.
S.NO Equipment Range Type Quantity
01 Voltmeter (0-300)v MI 1
02 Ammeter (0-5)A MI 1
03 1- Auto transformer 230/(0-270)V 1
04 Rheostat 100/5A Wire Wound 1
05 1- Energy meter 240V,5A 1
06 Wattmeter 5/10A,30V/1500W UPF 1
07 Connecting wires set
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6) Compare the theoretically & practically founded values.
7) Calculate the % Errors.
% Error=
8) Plot the graph between % error Vs power.
Precautions:-
1) Avoid loose connections.
2) Avoid parallax errors.
Result:-
The error of 1- energy meter for different loadings have been determined.
Observation Table:-
S.No Volts I (Ams) Px2(watts) Time for 10 rev(Sec)
No. of Revolutions
PxT(KWH) % Error
Result:-
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230
V, 1
- A
C Su
pp
ly, 5
0Hz
5/10A, 300V
1500W, UPF
5/10A, 300V
1500W, UPF
0-300V,MI
N
R
415V,3- AC
Supply,50Hz
Y
B
100/5A
0-5A, MI
R
Y
B
Phase Shifting T/F
3KVA,1- Variac
Fuse
N
Circuit Diagram: - Calibration of Dynamometer Power Factor meter
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2. Calibration of Dynamometer Power Factor meter
Aim:- Calibration of Dynamo meter Power factor Meter by phantom loading.
Apparatus:-
Theory:-
The connections of a single phase electro dynamo type. Power factor meter is show in figure.
It consists of fixed coil which acts as the current coil. This is split up in two parts and carries the current
of the circuit under test. Therefore the main current two identical pressure coils. A and B Provided on a
spindle constitute the moving system. Pressure coil A has a non inductive resistance R connected in
series with it. The two coils are connected across the voltage of the circuit the value of R&L are so
adjusted that the two coils carry the same value of current at normal frequency that is RL
Procedure:-
1) Connect the circuit as per the circuit diagram.
2) By adjusting the variac the rated voltage is applied across the pressure coil of wattmeter & power factor meter.
3) Rated current is made to pass through the coils.
4) Now adjust rotor position of phase shifting transformer for different values of power factor meter.
5) Tabulate the readings.
6) From wattmeter readings find values of power factor &compare from with value of power factor meter.
S.NO Equipment Range Type Quantity
01 Phase shifting T/F 1
02 Voltmeter (0-300)v MI 1
03 Ammeter (0-5)A MI 1
04 P.F Meter 5/10A,300v,1500W 1
05 I- Variac 230V/(0-270)V 1
06 Rheostat 100/5A 1
07 Wattmeter 5/10A,300V,300W 1
07 Connecting wires set
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Precautions:-
1) Avoid loose connections.
2) Avoid parallax errors.
Observation Table:-
S.No Voltmeter(V) I (Amps) P.F Meter Cos
Wattmeter (W)
Theoretical Cos
% Error
Result:-
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100/5A - +
Working battery 0-2V
RPS
0-30v
Fine
Coarse
Coarse
Fine
Stranded cell
1.0186V
Unknown R
1.5 To Potentiometer
5V
10V
50V
300V
0-30V,MC
G
Circuit diagram: - Calibration of PMMC voltmeter using Crompton D.C Potentiometer
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3. Calibration of PMMC voltmeter using Crompton D.C Potentiometer
Aim: To Determine Error given by voltmeter with DC potentiometer.
Apparatus:-
Theory:-
There are two types of potentiometers.
1.D.C potentiometer
2.A.C Potentiometer.
The potentiometer is extensively used for a calibration of voltmeters and ammeters and has
infect became the standard for the calibration of these instrument. The principle of operations of all
potentiometers is based on the circuit, all the resistors in a potentiometer with the exception of slide
wires are made of manganin. This is because manganin has a high stability a low temperature coefficient
and has freedom fro thermo electric effect against copper.
The slide wire is usually made of platinum sliver alloy and the sliding contacts are of a copper gold
sliver alloy .this combination of materials for slide wire and sliding contacts results in a good contact,
freedom from thermo electric emf and minimum wear of slide wire.
Procedure:-
1.connect the circuit elements as per the circuit diagram.
2.standeredise the given potentiometer.
3.Apply the voltage to potentiometer terminal.
4. Adjust the dial resistor for zero deflection of galvanometer.
5.compare the obtained value.
%Error=Instrument reading-actual reading Actual reading
S.NO Equipment Range Type Quantity
01 RPS (0-30)v 1
02 Voltmeter (0-30)v MC 1
03 Volt Ratio box 1
04 Potentiometer 1
05 Standard cell 0.0186 1
06 Connecting wires set
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Precautions:
1. Avoid loose connections.
2. Avoid Parallax Errors.
OBSERVATIONS TABLE:-
S.No Voltmeter(V) Potentiometer output
Potentiometer input
Result:-
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C
V=5V
+ -
R2
S
n m a
p 2
D Q
b
P
R
Measurement of Resistance using Kelvins Double Bridge
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4. Measurement of Resistance using Kelvins Double Bridge
Aim:-
To measure unknown low resistance using Kelvins double bridge.
Apparatus:-
Theory:-
The problem involved in the measurement of low resistance with an ordinary wheat stone
bridge an be eliminated using Kelvins double bridge. This bridge uses two ratio ARMS &a four terminal
low resistance standard resistor (S)
The outer ratio Arms consists of P&Q inner ratio ArmsP,2 Both
the arms are connected to the potential terminals so as to eliminate the effect of leads
Under balanced condition no current flow through the galvanometer and
hence the potential drop across the resistor of an outer Arms is equal to sum of drop across the low
resistance and inner arm resistance.
Procedure:-
1) Connect the circuit as per circuit diagram.
2) Connect the unknown resistance R.
3) Switch on the power supply.
4) By varying the standard resistance S obtain the balance condition (Null deflection ).
5) Calculate the unknown resistance by using the Formula.
SQ
PR
Precautions:-
1) Avoid loose connections.
S.NO Equipment Quantity
01 Kelvins Bridge board 1
02 Null detector 1
03 Supply voltage 1
04 Unknown Resistance 1
05 Connecting wires set
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2) Avoid parallax errors.
Result:-
The unknown resistance is calculating by using Kelvins double bridge.
Observation table:-
S.No R1() R2() R3() Rx (Theory) R3(Practical)()
Result:-
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Main
Fuse
r
Main
HT
HF
Charging Volt(0-60V)
Memory Dust
H.T Relay
Unit relay
115V 230V
11KV
Oil container
10
0
/5A
1- A
C 2
30
V
High Voltage
ON
HF
OFF
ON
Circuit Diagram:- Testing of transformer Oil
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5. Testing of transformer Oil
Aim:-
To test oil transformer determine the dielectric strength of oil.
Apparatus:-
Transformer oil test kit.
Name plate details:-
Input voltage:230/240V 1- 50HZ AC supply
Output voltage: (0-60)KVA
Capacity: 600 KVA
Theory:-
The oil transformer kit is used to determine the dielectric strength of oil these are generally
used in substations. It contains two electrodes of a small gap between there when ever break down
voltage occurs there will be a spark is observed at the high voltage side of the transformer. For
calibration the gap in between the two electrodes is 4MM. the voltage that is obtained when flash over
occurs is rapidly applied voltage.
Procedure:-
1) The oil is poured in a container known as test cell the electrodes are polish spheres perfectly of brass arranged horizontally a suitable gauge is used to adjust the gap.
2) While pouring the oil sample the test cell(container should )be thoroughly cleaned & the moisture & sypended particles should be avoided in fig shown below & experimental setup for finding out the dielectric strength of the give sample of oil.
3) The voltmeter is the connected on the primary side of high voltage side transformer for calibration.
4) Adjust the gap between the spheres is to 4MM with the help of gauge then pour transformer oil till a depth slurries are immersed.
5) Then increase the voltage gradually & continuously till a flashover of the gap is seen on the MCB apparatus note down this voltage. This voltage is known as rapidly applied voltage.
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6) The breakdown of the gap has taken please mainly due to field effect. The thermal effect is main as the time of application is short.
7) Next bring the voltage back Zero & star with 40% of rapidly applied voltage & weight for one min.sec if the flashover by take occurred if not
increase the voltage every time by 2
12 of the rapidly applied voltage and wait for one
min till the flash over is seen on the MCB trips. Note the voltage.
8) Repeat the experiment with different values of voltage.
9) The acceptable value is 30KV for 4mm & 2.5mm for 11KV the oil should be set for secondly.
Precautions:-
It is to be noted that the electrodes are immersed vertically in the oil. It is due to the fact
that when oil decomposes. Carbon particles being lighter rice up & if electrons are vertical
configurations, this well bridge the gap & the breakdown will take place.
Result:-
The dielectric strength of oil is determined.
Observation table:-
S/No Dielectric voltage Average value
Result:-
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Circuit Diagram:- Schering Bridge and Anderson Bridge
Schering Bridge:-
L1 R1
F
r
E1 E2
E4 E3
R2
D
R4
R1 R2
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Anderson Bridge:
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6. Schering Bridge and Anderson Bridge
I1/wc1
IIr1 Ir2
I2
C2
C1
a
b
c
I2
I1
I1
Cx
E1 E3
E4 E2
D
r1 R3
d R4
I2
Phasor Diagram:-
Ic I2
2
I1
2
E1=E2=I2/wc2
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Aim:-
To determine the unknown capacitance using Schering bridge & inductance using Anderson bridge.
Apparatus:-
Theory:-
Anderson Bridge:-
This bridge in fact is a modification of the self Maxwell s inductance Capacitance
bridge. In this method the self inductance is measured in terms of a standard capacitor. This method is
applicable for precise measurement of self inductance over a very wide range of values.
14
321 r
R
RRR
42244
31 )( RRRRr
R
RCL
The disadvantage of Anderson bridge is more complex than its proto type Maxwells
and is more parts and is more complicated to set up and manipulate. The balance equation are not
simple and in fact are much more tedious. An additional junction point increases the difficulty to
shielding the bridge.
Schering Bridge:-
The connection and phasor diagram of the bridge under balance conditions are show
in figure.
r1 =R3 C4/C2
c1 =C2 R4/R3
therefore values of capacitance c1 and its dissipation factor are obtained from the value of bridge
elements at balance permanently set up Schering bridges are sometimes arranged so that balancing is
done by adjustment of R2 & C4 with C2 & R4 remaining fixed. Since R3 appears in both the balance
S.NO Equipment Quantity
01 Schering Bridge kit 1
02 Anderson Bridge kit 1
03 Unknown Capacitor 1
04 Unknown Inductor 1
05 Connecting wires set
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equation and therefore there is some difficulty in obtaining balance but it has certain advantages as
explained below. The equations for C1=R4/R3 x C2 and since R4&C2 are fixed. The dial of R3 may be
calibrated to read the capacitance directly.
Procedure:-
Shearing Bridge:-
1) Connect the circuit as per circuit diagram.
2) By varying the balanced the condition.
3) Note down the value of C2,R2,R1
4) Calculate the value of Cx
1
22
R
RCCx
Anderson Bridge:-
1) Connect the circuit as per circuit diagram
2) By the varying r and R balanced the bridge.
3) Note down the values.
4) Calculate self inductance.
L1=C.R (Q+2r)
Precautions:-
1) Avoid loose connections.
2) Balance the bridge accurately.
Result:-
The unknown inductance & unknown capacitance had been found using Anderson &
Schering Bridge.
Shearing Bridge:-
Observation table:-
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S.No R2() C2(F) R1()
1
21
R
RCC (MF) RC
CR
1
2 ()
Anderson Bridge:-
Observation table:-
S.No C (F) R() r(K) L=CR(Q=2r)MH
Result:-
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Fuse 10A
3 Auto Transformer
414
V
3- I
N
D
U
C
T
I
V
E
L
O
A
D
(0-600)V
MI
V
M L
C V
A
M L
C
R
Y
B
N
Circuit Diagram:-Measurement of 3- Reactive Power using 1- Wattmeter
7. Measurement of 3- Reactive Power using 1- Wattmeter
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Aim:- Measurement of Reactive power of an 3- balanced inductance load using one 1-
Wattmeter.
Apparatus:-
Theory:-
For the measurement of reactive power in balanced 3- circuit only a single Dynamometer
type wattmeter is required.
The current coil is connected in series with load and the pressure coil is connected Across
the remaining two phase.
Let the current through current coil be Iph & potential appliance across the pressure coil be
V
VI=VY-VB=3 VPH.
This potential VI is leading R by 90o IR by hence wattmeter reading indicates.
WI=3 VPH IPH. Cos (-90o+)= =3 VPH IPH sin
Total reactive power (Q) obtained by Multiplying the wattmeter reading with =(-3)i.e Q=3 WI
Procedure:-
1) connect the apparatus as shown as circuit diagram.
2) Vary the auto transformer and set it to rated voltage .
3) Now Vary the 3- balanced load gradually.
4) Note down the reading of voltmeter, Ammeter & Wattmeter.
5) Calculate theoretical and Practical values of reactive power from the given formula.
Precautions:-
1) Avoid lose connections.
S.NO Equipment Range Type Quantity
01 Wattmeter 5/10A,600v,1500W UPF 1
02 5/10A,300v,300W
03 Voltmeter (0-600)v MI 1
04 Ammeter (0-10)A MI 1
05 3- inductive balanced --------------- 1
06 3- Auto Transformer --------------- 1
07 Connecting wires --------------- set
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2) Avoid parallax errors.
Result:-
The measurement of 3- Reactive power using 1- Wattmeter has been clone and theoretical & practical values has been compared.
Observation Table:-
S.No W1 W2 Volts P=3* W1 S=3VI =tan-1(Q/P)
Q=3VI sin
Q=S2-P2 I(Amps)
Result:-
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Fuse 10A
230V
V
115V
V
(0-10)A
MI
(0-30)V
MI
1-
230V
50 Hz AC
Supply
Ph
N 1 -Transformer
3KVA, 230V/ 115V
DPST
Variac
230V/ (0-270)V,10A
V
A1
(0-10)A
MI c A3
(0-5)v
MI
100/5A
A2
Fuse 10A
230V
V
115V
V
(0-15)A
MI
(0-50)V
MI
1-
230V
50 Hz AC
Supply
Ph
N 1 -Transformer
3KVA, 230V/ 115V
DPST
Variac
230V/ (0-270)V,10A
V1
A
V2
100/5A
(0-30)v
MI (0-30)v
MI
V3
Measurement of Parameters of A coil
3-AmmeterMethod:-
3-Voltmeter Method:-
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8. Measurement of Parameters of A coil
Aim:- Measurement of Parameters of a choke coil using 3 voltmeter and 3ammeter
To obtain the parameters of given coil using
A) 3 Voltmeter method
B) 3 Ammeter method
Apparatus:-
3 Voltmeter Method
3 Ammeter Method
Theory:-
The parameters of a coil like Inductance & Resistance can be calculated by using 3-Voltmeter
& 3-Ammeter methods.
In the three voltmeter method a suitable current is passed through the coil, in
series with a non inductive resistance R and the voltage drops across both parts of the circuit and across
the calculated and the R&L can be easily determined using the power factor.
In the 3-Ammeter method the non-inductive resistance R, together with an ammeter is
connected in parallel with the coil whose inductance is to be measured.
Procedure:-
3-voltmeter Method:-
S.NO Equipment Range Type Quantity
01 Voltmeter 0-230V MI 3
02 Ammeter 0-1A MI 1
03 1- Auto transformer 230V/(0-270)V MI 1
04 Rheostat 100/5A Wire wound 1
05 Connecting wires 1 Set
S.NO Equipment Range Type Quantity
01 Voltmeter 0-230V MI 1
02 Ammeter 0-10A MI 2
03 Ammeter 0-5A MI 1
04 1- Auto transformer 230V/(0-270)V MI 1
05 Rheostat 100/5A Wire wound 1
06 Connecting wires 1 Set
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1) Connect the circuit as shown in the circuit diagram.
2) Vary the auto transformer knob till rated current flows in the circuit.
3) Not down the voltmeters & Ammeter readings.
4) Calculate the resistance and reactance of the coil.
3-Ammeter Method:-
1) Connect the circuit as shown in the circuit diagram.
2) Vary the auto transformer knob till we get rated voltage.
3) Note down the voltmeter & Ammeters readings.
4) Calculate the resistance & Reactance of the coil using above formula.
Observation Table:-
3-Voltmeter Method:
S.NO I (Amps) V1 (V) V2(V) V3(V)
3-Ammeter Method:
S.NO V (Volts) I1 (Amps) I2(Amps) I3(Amps)
Precautions:-
1) Avoid parallax errors.
2) Avoid lose connections.
Result:-
The parameters of a coil Referred to primary are calculated.
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ADDITIONAL EXPERIMENTS:-
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230
V, 1
- A
C Su
pp
ly, 5
0Hz
5/10A, 300V
1500W, UPF
5/10A, 300V
1500W, UPF
0-300V,MI
N
R
415V,3- AC
Supply,50Hz
Y
B
100/5A
0-5A, MI
R
Y
B
Phase Shifting T/F
3KVA,1- Variac
Fuse
N
Circuit Diagram:- Calibration of L.P.F Watt Meter by Phantom testing
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9. Calibration of L.P.F Watt Meter by Phantom testing
Aim:- Calibration of I- Power factor Meter by (L.P.F) phantom loading.
Apparatus:-
Theory:-
The connections of a single phase electro dynamo type. Power factor meter is show in figure.
It consists of fixed coil which acts as the current coil. This is split up in two parts and carries the current
of the circuit under test. Therefore the main current two identical pressure coils. A and B Provided on a
spindle constitute the moving system. Pressure coil A has a non inductive resistance R connected in
series with it. The two coils are connected across the voltage of the circuit the value of R&L are so
adjusted that the two coils carry the same value of current at normal frequency that is RL
Procedure:-
7) Connect the circuit as per the circuit diagram.
8) By adjusting the variac the rated voltage is applied across the pressure coil of wattmeter & power factor meter.
9) Rated current is made to pass through the coils.
10) Now adjust rotor position of phase shifting transformer for different values of power factor meter.
11) Tabulate the readings.
12) From wattmeter readings find values of power factor &compare from with value of power factor meter.
Precautions:-
3) Avoid loose connections.
S.NO Equipment Range Type Quantity
01 Phase shifting T/F 1
02 Voltmeter (0-300)v MI 1
03 Ammeter (0-5)A MI 1
04 P.F Meter 5/10A,300v,1500W 1
05 I- Variac 230V/(0-270)V 1
06 Rheostat 100/5A 1
07 Wattmeter 5/10A,300V,300W 1
07 Connecting wires set
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4) Avoid parallax errors.
Result:-
The L.P.F wattmeter has been calibrated by phantom loading. An average error of 5% is found.
Observation Table:-
S.No Voltmeter(V) I (Amps) P.F Meter Cos
Wattmeter (W)
Theoretical Cos
% Error
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Circuit Diagram:- Measurement of % Ratio & phase Angle Error of A Current Transformer
A
V
A
L
O
A
D
(0300)V
MI
(0-10)A
MI
(0100)MA
MI
3KW,10A
I-
Fuse 10A
Fuse 10A
DPST
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10. Measurement of % Ratio & phase Angle Error of a Current Transformer
Aim:
To test current transformer by direct loading.
Apparatus:-
Theory:-
Depending open the construction of primary winding used C.TS are two types.
1)Wound type Current transformer.
2) Bar type Current Transformer.
In wound type of C.TS the primary winding consists of more than one complete turn which is wound
on the core.
For a wound type C.T either rectangular or standing or ring shaped cores are used the material to be
used for core should have high permeability and low magnetic loss, so core is made up of nickel iron
alloy or oriented electrical steel. The bare type C.Ts are used when the primary current is large it has
robust construction among all the C.Ts the core is ring shaped.
Procedure:-
1) Connect the circuit as for circuit diagram.
2) Set the input voltage to 230V rated by varying 1- Variac.
3) Note down the readings of Ammeter in primary & Secondary circuit of current transformer at Various loads.
4) Repeat the steps for various positions of primary and current T/F in middle corner etc.
S.NO Equipment Range Type Quantity
01 Current T/F 100/5A 1
02 1- Variac 230/(0-270)V
03 Voltmeter (0-300)v MI 1
04 Ammeter (0-15)A,(0-100)MA MI 1
05 Resistive load 1- 3KW,10A,230V 1
06 Connecting wires set
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5) Compare the current transformer ratio with its value and % error is found.
Precautions:-
1) Avoid loose connections.
2) Avoid parallax errors.
Result:-
Current T/F has been tested by direct loading.
OBSERVATION TABLE:_
S.NO Current Transformer (Center) Current Transformer (Near)
Primary(A) Secondary(MA) Primary(MA) Secondary(MA)
Calculation Table:-
Center: Near:
I1/I2 % Error
I1/I2 % Error
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Circuit Diagrams:- Calibration of Domestic Applications
V
A
L
O
A
D
(0300)V
MI
(0-10)A
MI Fuse 5A
Fuse 5A
DPST
1-
230V
50 Hz AC
Supply
1- ,VARIAC
3KVA
V
A
(0300)V
MI
(0-2)A
MI
Bulb
Fuse 2A
Fuse 2A
DPST
M L
C 1-
230V
50 Hz AC
Supply
V
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11. Calibration of Domestic Applications
Aim:-
To test and determine the Functioning of 5A fuse A 100W bulb And a 70w Ceiling Fan.
Apparatus:-
S.no Apparatus Type Range Quantity
01 I- Variac 230/(0-270) 1
02 Wattmeter UPF 5A,300V,3000W 1
03 Voltmeter MI (0-300)V 1
04 Ammeter MI (0-10)A 1
05 Rheostat Wire Wound 100 1
06 Bulb 100W 1
07 Fuse 5A 1
08 Ceiling Fan 80W 1
09 Connecting Wires Set
Theory:-
Fuse Wire:-
A Fuse is a thin wire which has a current rating. The current about this fuse wire break.
Bulb:-
A Bulb is a glowing thing which has a power rating when the voltage is excited the bulb
V
A
(0300)V
MI
(0-10)A
MI Fuse 5A
Fuse 5A
DPST
M L
C V
ff Fan
1-
230V
50 Hz AC
Supply
1- ,VARIAC
3KVA
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filament blows off.
FAN:-
A Fan is a rotating motor finding the efficiency.
Procedure:-
Fuse:-
1 Connect the circuit as for the circuit diagram.
2 Switch on the power supply and gradually increase current through the fuse by increasing load.
3 note the value of current rating for which the fuse wire blows.
Electrical Bulb:-
1 Connect the circuit as for the circuit diagram.
2 By gradually varying the variac . apply rated voltage to the bulb indicated by voltmeter across bulb.
3 Note the readings.
Ceiling FAN:-
1 Connect the circuit as for the circuit diagram.
2 Apply rated voltage.
3 Note down readings of voltmeter by varying regulator.
Precautions:-
1 Avoid the loose connections.
2 Avoid the parallel errors.
OBSERVATION TABLE:-
S.NO Equipment Voltage(V) Current(A) Ratting Wattmeter(W)
01
02
03
Result:-
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