EC2259
EC 2259
Electrical Engineering And Control System Lab Manual
ELECTRICAL ENGINEERING AND CONTROL SYSTEM LAB
0 0 3 2
AIM
To expose the students to the basic operations of electrical machines and help them to
develop experimental skills.
1. To study the concepts, performance characteristics, time and frequency response of
linear systems.
2. To study the effects of controllers.
1. Open circuit and load characteristics of separately excited and self excited D.C.
generator.
2. Load test on D.C. shunt motor.
3. Swinburne’s test and speed control of D.C. shunt motor.
4. Load test on single phase transformer and open circuit and short circuit test on single
phase transformer
5. Regulation of three phase alternator by EMF and MMF methods.
6. Load test on three phase induction motor.
7. No load and blocked rotor tests on three phase induction motor (Determination of
equivalent circuit parameters)
8. Study of D.C. motor and induction motor starters.
9. Digital simulation of linear systems.
10. Stability Analysis of Linear system using Mat lab.
11. Study the effect of P, PI, PID controllers using Mat lab.
12. Design of Lead and Lag compensator.
13. Transfer Function of separately excited D.C.Generator.
14. Transfer Function of armature and Field Controller D.C.Motor.
P = 45 Total = 45
1. Open circuit and load characteristics of separately excited and self excited D.C.
generator.
Sl. No.
1
2
Apparatus
Motor Generator set
Rheostat
3
Voltmeter DC
4
Ammeter DC
5
6
7
DPST switch
Three point starter
Tachometer
Range
200Ω, 5A
175Ω, 1.5A
300V
30V
30A
2A
Quantity
1
1
2
1
1
1
2
2
1
1
EC2259
2.
Electrical Engineering And Control System Lab Manual
Load test on D.C. shunt motor.
Sl. No.
1
2
3
4
5
6
7
3.
Apparatus
Range
175Ω, 1.5A
300V
30A
DC Motor
Rheostat
Voltmeter DC
Ammeter DC
DPST switch
Three point starter
Tachometer
Quantity
1
1
1
1
1
1
1
Swinburne’s test and speed control of D.C. shunt motor
Sl. No.
1
2
Apparatus
DC Motor
Rheostat
Range
100Ω, 5A & 175Ω, 1.5A
3
4
Voltmeter DC
Ammeter DC
300V
5A
2A
5
6
DPST switch
Tachometer
Quantity
1
1
1
1
1
1
1
1
4. Load test on single-phase transformer and open circuit and short circuit test on
single-phase transformer.
Sl. No.
1
2
5.
Apparatus
Single phase Transformer
Wattmeter
Range
300V, 5A,UPF & 300V,
5A,LPF
300V
5A
30A
3
4
Voltmeter AC
Ammeter AC
5
6
Single phase auto-transformer
Resistive load
Regulation of three-phase alternator by EMF and MMF method.
Sl. No.
Apparatus
Range
1
Motor Alternator set
2
Rheostat
200Ω, 5A &175Ω, 1.5A
3
4
5
6
Voltmeter DC
Voltmeter AC
Ammeter DC
Ammeter AC
DPST switch
TPST switch
Tachometer
300V
600V
2A
30A
Quantity
1
1
1
2
1
1
1
1
Quantity
1
1
1
1
1
1
1
1
1
1
EC2259
6.
Electrical Engineering And Control System Lab Manual
Load test on three phase Induction motor.
Sl. No.
1
2
3
4
5
6
7
7.
Apparatus
Three Phase Induction Motor
Wattmeter
Voltmeter AC
Ammeter AC
Brake drum arrangement
Star delta starter
Tachometer
Range
600V, 10A,UPF
600V
10A
Quantity
1
2
1
1
1
1
No load and blocked rotor test on three-phase induction motor (Determination of
equivalent circuit parameters)
Sl. No.
1
2
Apparatus
Three Phase Induction Motor
Wattmeter
3
Voltmeter AC
4
Ammeter AC
5
6
Brake drum arrangement
Three phase auto-transformer
Range
600V, 10A,UPF
600V, 5A,LPF
600V
150V
10A
5A
Quantity
1
2
2
1
1
1
1
1
8. Study of D.C. motor and Induction motor starters.
Sl. No.
1
2
3
4
5
Apparatus
Three point starter
Four point starter
Star-delta starter
DOL starter
Three phase auto-transformer
Quantity
9. Digital simulation of linear systems.
Simulink software for minimum 3 users license
10. Stability analysis of linear system using Mat lab.
Matlab software for minimum 3 users license
11. Study of effect of P, PI, PID controllers using Mat lab.
Matlab software for minimum 3 users license
1
1
1
1
1
EC2259
Electrical Engineering And Control System Lab Manual
12. Design of lead and lag compensator.
Sl. No.
1
2
3
4
Apparatus
Resistor
Capacitor
Function generator
Bread Board
13. Transfer function of separately excited D.C. generator.
Sl. No.
1
2
Apparatus
Motor Generator set
Rheostat
3
Voltmeter DC
4
Ammeter DC
5
6
7
DPST switch
Three point starter
Tachometer
Range
200Ω, 5A
175Ω, 1.5A
300V
30V
30A
2A
Quantity
1
1
2
1
1
1
2
2
1
1
14. Transfer function of armature and field controller D.C. motor.
Sl. No.
1
2
3
4
5
6
7
Apparatus
DC Motor
Rheostat
Voltmeter DC
Ammeter DC
DPST switch
Three point starter
Tachometer
Range
175Ω, 1.5A
300V
30A
Quantity
1
1
1
1
1
1
1
EC2259
Electrical Engineering And Control System Lab Manual
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EC2259
Electrical Engineering And Control System Lab Manual
LOAD TEST ON DC SHUNT MOTOR
AIM
To conduct the load test on a given dc shunt motor and draw its performance curves.
NAME PLATE DETAILS
FUSE RATING
125% of rated current (full load current)
APPRATUS REQUIRED
NAME OF THE
APPARATUS
S. NO
TYPE
RANGE
QUANTITY
1
Ammeter
MC
(0-20A)
1
2
Voltmeter
MC
(0-300V)
1
3
Rheostat
Wire wound
250 , 2A
1
4
Tachometer
Digital
FORMULAE
1. Torque T = (S1~S2) × (R+t/2) × 9.81 in N-m.
Where R- Radius of the Break drum in m.
t- Thickness of the Belt in m.
S1,S2- Spring balance reading in Kg.
2. Input power = VL × IL in Watts.
Where VL – Load Voltage in Volts.
IL- Load current in Amps.
3. Output power = 2 NT/60 in Watts.
Where N- Speed of the armature in rpm.
T- Torque in N-m.
4. Percentage of Efficiency = (Output power/Input power) × 100
1
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR LOAD TEST ON DC SHUNT MOTOR
(0-20A)
MC
3 POINT STARTER
L
F A
A
Fuse
250 , 2A
220V
DC SUPPLY
A
F
D
P
S
T
S
V
(0-300V)
MC
S1
S2
M
AA
FF
BRAKE DRUM
Fuse
Model Graph
(A) Electrical characteristics
N
(B) Mechanical characteristics
T
%
T in N-m
N in rpm
Speed in rpm
Torque Vs Speed
Torque in N-m
IL in Amps
(C) Torque, Speed Vs Load Current
Output power in watts
Torque in N-m
%
Speed in rpm
IL
Speed
Torque
Load Current in Amps
EC2259
Electrical Engineering And Control System Lab Manual
PRECAUTION
•
•
•
The motor field rheostat should be kept at minimum resistance position.
At the time of starting, the motor should be in no load condition.
The motor should be run in anticlockwise direction.
PROCEDURE
•
•
•
•
•
•
Connections are given as per the circuit diagram.
Using the three-point starter the motor is started to run at the rated speed by adjusting the
field rheostat if necessary.
The meter readings are noted at no load condition.
By using the Break drum with spring balance arrangement the motor is loaded and the
corresponding readings are noted up to the rated current.
After the observation of all the readings the load is released gradually.
The motor is switched off by using the DPIC switch.
GRAPH
The graphs are drawn as
• Output power Vs Efficiency
• Output power Vs Armature current
• Output power Vs Torque
• Output power Vs Speed
• Torque Vs Speed
• Torque Vs Armature current
• Speed Vs Armature current
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for load test on DC shunt motor
Radius of the brake dram =
S.No
Load
Current
(IL)
Load
Voltage
(VL)
Speed of
the motor
(N)
Thickness of the belt =
Spring balance reading
S1
Amps
Volts
Rpm
Kg
S2
Kg
Torque (T)
(S1~S2)(R+t/2)(9.81)
Output
power
2 NT/60
Input
power
(VLIL)
Efficiency (η
η)
O/p / I/p
x100
N-m
Watts
Watts
%
S1~S2
Kg
EC2259
Electrical Engineering And Control System Lab Manual
MODEL CALCULATION
RESULT
Thus the load test on DC shunt motor and its performance curves are drawn.
EC2259
Electrical Engineering And Control System Lab Manual
SPEED CONTROL OF DC SHUNT MOTOR
AIM
To conduct an experiment to control the speed of the given dc shunt motor by field and
armature control method also to draw its characteristic curves.
NAME PLATE DETAILS
FUSE RATING
10% of rated current (full load current)
APPRATUS REQUIRED
S.NO
NAME OF THE
APPARATUS
TYPE
RANGE
QUANTITY
1
Ammeter
MC
(0-2A)
1
2
Ammeter
MC
(0-10A)
1
3
Voltmeter
MC
(0-300V)
1
4
Rheostat
Wire wound
250 , 2A
1
5
Rheostat
Wire wound
50 , 5A
1
6
Tachometer
Digital
PRECAUTION
•
•
•
•
The motor field rheostat should be kept at minimum resistance position.
The motor armature rheostat should be kept at maximum resistance position.
The motor should be in no load condition throughout the experiment.
The motor should be run in anticlockwise direction.
1
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR SPEED CONTROL OF DC SHUNT MOTOR
(0-10A)
MC
3 POINT STARTER
L
A
F A
50 , 5A
Fuse
A
D
P
S
T
S
220V
DC SUPPLY
250 , 2A
(0-2A)
MC
A
F
M
FF
V
(0-300V)
MC
AA
Fuse
Tabulation for Speed control of DC Shunt motor
Armature Control Method
Field Current:
S.No.
Prepared by
Field Control Method
Armature Current:
Armature
Voltage (Va)
Speed
(N)
Field Current
(If)
Speed
(N)
Volts
RPM
Amps
RPM
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Model Graph
(A) Armature Control Method:
(B) Field Control Method:
Field Current Vs Speed
Speed in rpm
Speed in rpm
Armature Voltage Vs Speed
Field Current in Amps
Armature Voltage in Volts
PROCEDURE
Field Control Method (Flux Control Method)
•
•
•
•
•
Connections are given as per the circuit diagram.
Using the three point starter the motor is started to run.
The armature rheostat is adjusted to run the motor at rated speed by means of
applying the rated voltage.
The field rheostat is varied gradually and the corresponding field current and speed
are noted up to 120% of the rated speed by keeping the Armature current as
constant.
The motor is switched off using the DPIC switch after bringing all the rheostats to
their initial position.
Armature Control Method (Voltage Control Method)
•
•
•
•
•
Connections are given as per the circuit diagram.
Using the three point starter the motor is started to run.
The armature rheostat is adjusted to run the motor at rated speed by means of
applying the rated voltage.
The armature rheostat is varied gradually and the corresponding armature voltage
armature current and speed are noted up to the rated voltage.
The motor is switched off using the DPIC switch after bringing all the rheostats to
their initial position
GRAPH
The graph are drawn as
•
•
Field current Vs Speed
Armature current Vs Speed
RESULT
Thus the speed control of the given DC shunt motor using field control and armature
control method and its characteristic curves are drawn.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
SWINBURNE’S TEST
AIM
To predetermine the efficiency of a given dc shunt machine when working as a motor as well
as generator by Swinburne’s test and also draw the characteristic curves.
NAME PLATE DETAILS
FUSE RATING
10% of rated current (full load current)
APPRATUS REQUIRED
S.NO
NAME OF THE
APPARATUS
TYPE
RANGE
QUANTITY
1
Ammeter
MC
(0-2A)
1
2
Ammeter
MC
(0-10A)
1
3
Voltmeter
MC
0-300V
1
4
Rheostat
Wire wound
250 ,2A
1
5
Tachometer
Digital
1
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR SWINEBURN’S TEST
(0-10A)
MC
3 POINT STARTER
L
A
F A
Fuse
A
250 , 2A
220V
DC SUPPLY
D
P
S
T
S
V
(0-2A)
MC
A
F
(0-300V)
MC
M
AA
FF
Fuse
Tabulation to find out the Constant loss (Wco)
Terminal
Voltage (V)
No load
Current (I0)
Field Current
(If)
Volts
Amps
Amps
S.No.
No load
Armature
Current (Ia0)
Amps
Constant Loss
2
WCO = VI0-Ia0 Ra
Watts
Resultant tabulation to find out the Efficiency (Running as motor)
Armature Resistance (Ra)=
Constant loss
(WC)=
Load
Fraction Current IL=
S.No.
of
X×Ir
Load
(X)
Amps
1
1/4
2
1/2
3
3/4
4
1
Armature
Current
Ia= IL- If
Armature
Cu Loss
WCu=Ia2Ra
Total
Loss
WTotal
Amps
Watts
Watts
Rated Current (Ir)=
Field Current (If) =
Input
Output Power
Power
Wo =Wi- WTotal
Wi=VLIL
Watts
Watts
Efficiency
= Wo/ Wi
%
EC2259
Electrical Engineering And Control System Lab Manual
FORMULAE
1. Armature resistance (Ra)
= 1.6 × RDC in Ohms.
Where,
RDC – Resistance of the Armature coil, when it is energized by DC supply.
2. Constant loss (WCO )
= (V Io-Iao2Ra) in Watts..
Where V = Terminal Voltage in Volts
Io = No Load Current in Amps
Iao = No Load Armature Current. in Amps
3. Armature Current (Ia)
= (IL ± If ) in Amps.
Where, + is used for Generator,
- is used for Motor.
4. Copper loss (WCU )
= Ia2Ra in Watts.
5. Total loss
= Constant loss + Copper loss in Watts
6. Input power for motor / Output power for generator = V IL in Watts
Where, IL is Load current in Amps
7. Output power for motor
= Input power + losses
Input power for Generator = Output power - losses
8. Percentage of Efficiency = (Output power/Input power) × 100
PRECAUTION
•
•
•
The motor field rheostat should be kept at minimum resistance position.
The motor should be at no load condition through out the experiment.
The motor should be run in anticlockwise direction.
PROCEDURE
•
•
•
•
•
•
Connections are given as per the circuit diagram.
By using the three point starter the motor is started to run at the rated speed.
The meter readings are noted at no load condition.
The motor is switched off using the DPIC switch.
After that the Armature resistive test is conducted as per the circuit diagram and the voltage
and current are noted for various resistive loads.
After the observation of readings the load is released gradually.
EC2259
Electrical Engineering And Control System Lab Manual
Running as generator
Armature Resistance (Ra)=
Constant loss
(WC)=
Fraction
S.No.
of
Load
(X)
1
1/4
2
1/2
3
3/4
4
1
Rated Current (Ir)=
Field Current (If)=
Load
Current
IL= X×Ir
Armature
Current
Ia= IL+ If
Armature
Cu Loss
WCu=Ia2Ra
Total
Loss
WTotal
Output
Power
Wo=VLIL
Amps
Amps
Watts
Watts
Watts
Input Power
Wi
=Wo+WTotal
Efficiency
= Wo/
Wi
Watts
%
EC2259
Electrical Engineering And Control System Lab Manual
Model Graph
Generator
Efficiency
Motor
Output Power (Wo) in Watts
GRAPH
The graph drawn between Load current Vs Efficiency
RESULT
Thus the efficiency of the given DC shunt machine by Swinburne’s test when working as a
motor as well as generator and also draw the characteristic curves are drawn.
EC2259
Electrical Engineering And Control System Lab Manual
OPEN CIRCUIT TEST AND LOAD TEST ON SELF EXCITED DC
SHUNT GENERATOR
AIM
To conduct the open circuit test and the load test on a given self excited dc shunt generator and
draw the characteristic curves.
NAME PLATE DETAILS
FUSE RATING
125% of rated current (full load current)
APPRATUS REQUIRED
S.NO
NAME OF THE
APPARATUS
TYPE
RANGE
QUANTITY
1
Ammeter
MC
(0-2A)
1
2
Ammeter
MC
(0-20A)
2
3
Voltmeter
MC
(0-300V)
1
4
Rheostat
Wire wound
250 , 2A
1
5
Rheostat
Wire wound
350 , 1.5A
1
6
Tachometer
Digital
-
1
7
Resistive Load
Variable
-
1
PRECAUTION
•
•
•
The motor field rheostat should be kept at minimum resistance position.
The generator field rheostat should be kept at maximum resistance position.
At the time of starting, the generator should be in no load condition.
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR OPEN CIRCUIT AND LOAD TEST ON SELF EXCITED
DC SHUNT GENERATOR
3 POINT STARTER
F A
A
Fuse
220V
DC SUPPLY
250 , 2A
D
P
S
T
S
F
17
Fuse
A
(0-20A)
MC
F
M
FF
Prepared by
A
(0-2A)
MC
AA
G
AA
A
A
1050 , 1.5A
L
(0-300V)
MC
Fuse
V
(0-20A)
MC
D
P
S
T
S
L
O
A
D
FF
Fuse
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
PROCEDURE
Open circuit test
•
•
•
•
Connections are given as per the circuit diagram.
The Prime Mover is started with the help of the three point starter and it is made to
run at rated speed when the Generator is disconnected from the load by DPST
switch.
By varying the Generator field rheostat gradually, the Open Circuit Voltage (Eo)
and corresponding Field Current (If) are tabulated upto 150 % of Rated Voltage of
Generator.
The motor is switched off by using the DPIC switch after bringing all the rheostats
to their initial position.
Load test
•
•
•
•
•
•
•
Connections are given as per the circuit diagram.
The Prime Mover is started with the help of the three point starter and it is made to
run at rated speed when the Generator is disconnected from the load by DPST
switch.
By varying the Generator field rheostat gradually, the Rated Voltage (Eg) is
obtained.
The Ammeter and Voltmeter readings are observed at no load condition.
The Ammeter and Voltmeter readings are observed for different loads up to the
rated current by closing the DPST switch.
After tabulating all the readings the load is brought to its initial position gradually.
The Prime Mover is switched off using the DPIC switch after bringing all the
rheostats to their initial position.
GRAPH
The graph are drawn as
• Open Circuit Voltage Vs Field Current
• Load Voltage Vs Load Current
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for OC and Load test on self excited DC Shunt Generator
Generator Armature Resistance (Ra):
S.No.
OC Test
Field
Open circuit
Voltage
Current
(E0)
(If)
Volts
Amps
Load
Voltage
(VL)
Load
Current
(IL)
Volts
Amps
Load Test
Armature Armature
Current
Drop
(Ia)
Ia Ra
Amps
Volts
Generated emf
Eg=VL+ Ia Ra
Volts
Model Graph
Field Current (If) in
Amps
(EgVs Ia)
Armature Current (Ia)
in Amps
Load Voltage (VL) in Volts
(E0) Vs (If)
(B) Internal (EgVs Ia) and External (VLVs IL) Characteristics
Generated EMF (Eg) in Volts
Open Circuit Voltage (E0)
in Volts
(A) Open Circuit Characteristics
(VLVs IL)
Load Current (IL) in Amps
RESULT
Thus the open circuit test and load test on a given self excited DC generator and the
characteristic curves are drawn.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
OPEN CIRCUIT TEST AND LOAD TEST ON SEPARATELY EXCITED
DC GENERATOR
AIM
To conduct the open circuit test and the load test on a given separately excited dc generator and
draw the characteristic curves.
NAME PLATE DETAILS
FUSE RATING
125% of rated current (full load current)
APPRATUS REQUIRED
S.NO
NAME OF THE
APPARATUS
TYPE
RANGE
QUANTITY
1
Ammeter
MC
(0-2A)
1
2
Ammeter
MC
(0-20A)
2
3
Voltmeter
MC
(0-300V)
1
4
Rheostat
Wire wound
250 , 2A
1
5
Rheostat
Wire wound
350 , 1.5A
1
6
Tachometer
Digital
-
1
7
Resistive Load
Variable
-
1
PRECAUTION
•
•
•
The motor field rheostat should be kept at minimum resistance position.
The generator field rheostat should be kept at maximum resistance position.
At the time of starting, the generator should be in no load condition.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR OPEN CIRCUIT AND LOAD TEST ON SEPERATELY EXCITED
DC GENERATOR
(0-20A)
MC
3 POINT STARTER
L
F A
220V
DC SUPPLY
250 , 2A
D
P
S
T
S
A
A
Fuse
F
A
A
FF
M
AA
(0-300V)
MC
G
V
F
FF
Fuse
AA
(0-20A)
MC
D
P
S
T
S
L
O
A
D
(0-2A)
A
MC
23
Fuse
220V
DC SUPPLY
D
P
S
T
S
Fuse
Fuse
350 , 1.5A
Fuse
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
PROCEDURE
Open circuit test
•
•
•
•
Connections are given as per the circuit diagram.
The Prime Mover is started with the help of the three point starter and it is made to run at rated
speed when the Generator is disconnected from the load by DPST switch.
By varying the Generator field rheostat gradually, the Open Circuit Voltage (Eo) and
corresponding Field Current (If) are tabulated upto 150 % of Rated Voltage of Generator.
The motor is switched off by using the DPIC switch after bringing all the rheostats to initial
position.
Load test
•
•
•
•
•
•
•
Connections are given as per the circuit diagram.
The Prime Mover is started with the help of the three point starter and it is made to run at rated
speed when the Generator is disconnected from the load by DPST switch..
By varying the Generator field rheostat gradually, the Rated Voltage (Eg) is obtained.
The Ammeter and Voltmeter readings are observed at no load condition.
The Ammeter and Voltmeter readings are observed for different loads up to the rated current by
closing the DPST switch..
After tabulating all the readings the load is brought to initial position.
The motor is switched off using the DPIC switch after bringing all the rheostats to initial position.
GRAPH
The graph drawn as
• Open Circuit Voltage Vs Field Current
• Load Voltage Vs Load Current
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for OC and Load test on separately excited DC Generator
Generator Armature Resistance (Ra):
S.No.
OC Test
Open circuit
Field
Voltage
Current
(E0)
(If)
Volts
Amps
Load
Voltage
(VL)
Load
Current
(IL)
Volts
Amps
Load Test
Armature Armature
Current
Drop
(Ia)
Ia Ra
Amps
Volts
Generated emf
Eg=VL+ Ia Ra
Volts
Model Graph
Field Current (If) in
Amps
(EgVs Ia)
Armature Current (Ia)
in Amps
Load Voltage (VL) in Volts
(E0) Vs (If)
(B) Internal (EgVs Ia) and External (VLVs IL) Characteristics
Generated EMF (Eg) in Volts
Open Circuit Voltage (E0)
in Volts
(A) Open Circuit Characteristics
(VLVs IL)
Load Current (IL) in Amps
RESULT
Thus the open circuit test and load test on a given separately excited DC generator and the
characteristic curves are drawn.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
LOAD TEST ON SINGLE PHASE TRANSFORMER
AIM
To conduct the load test on a given single phase transformer and draw its performance curves.
NAME PLATE DETAILS
FUSE RATING
Primary Current = KVA Rating of the Transformer / Primary Voltage.
Secondary Current = KVA Rating of the Transformer / Secondary Voltage.
125% of Primary current (fuse rating for primary side)
125% of Secondary current (fuse rating for secondary side)
APPRATUS REQUIRED
S.NO
NAME OF THE
APPARATUS
TYPE
RANGE
QUANTITY
1
Ammeter
MI
(0-5A)
1
2
Ammeter
MI
(0-20A)
1
3
Voltmeter
MI
(0-150V)
1
4
Voltmeter
MI
(0-300V)
1
5
6
Watt meter
UPF
300V, 5A
1
Auto Transformer
1φ
230/(0-270V
1
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR LOAD TEST ON SINGLE PHASE TRANSFORMER
(0-5A)
MI
A
P
A
SPSTS
(0-10A)
MI
300V, 5A UPF
M
L
A
Fuse
Fuse
C
B
1Ø, 230V, 50Hz
AC SUPPLY
V
150V
P1
S1
(0-150V)
MI
(0-300V)
MI
V
33
P2
D
P
S
T
S
L
O
A
D
S2
C
NL
N
230/(0-270V)
1Ø AUTO
TRANSFORMER
Fuse
1Ø 230/110V, 1KVA
STEP DOWN
TRANSFORMER
EC2259
Electrical Engineering And Control System Lab Manual
FORMULAE
1. Input Power =Wattmeter reading × Multiplication factor in Watts
Where,
(Rating of pressure coil × Rating of current coil × pf )
Multiplication factor =
Full Scale Reading
2.Output power = VSY × ISY × cosφ in Watts.
Where VSY - Secondary Voltage in Volts.
ISY- Secondary current in Amps.
3.Percentage of Efficiency =
× 100 %
Output Power
Input Power
4.Percentage of Regulation =
× 100 %
VO – VL
VO
Where, VO – No Load Voltage in Volts
VL – Load Voltage in Volts
PRECAUTION
•
•
No Load Condition should be observed at the time of starting
Meters are checked for proper Type and rating.
PROCEDURE
•
•
•
•
•
•
•
•
•
Connections are given as per the circuit diagram.
The SPST Switch on the Primary side is closed and the DPST Switch on the Secondary side is
opened.
The Autotransformer is adjusted to Energize the transformer with rated Primary Voltage
The Volt meters and Ammeters Readings are noted and tabulated at No load condition
The DPST switch on the secondary side is closed.
The transformer is loaded upto 130% of the Rated Load, corresponding Ammeters, Voltmeters
and Wattmeters readings are noted and tabulated.
After the observation of all the readings the load is released gradually to its initial position.
The Autotransformer is brought to its initial position
The Supply is switched off.
GRAPH
The graph drawn as
• Output power Vs Efficiency
• Output power Vs Regulation
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for Load test on single phase transformer
Multiplication Factor =
S.No
Primary
Voltage
(VPy)
Volts
Prepared by
Primary
Current
(IPy)
Amps
Secondary
Voltage
(VSy)
Volts
Secondary
Current
(ISy)
Amps
Wattmeter
readings
(W)
Obs. Act.
Watts
Input
power
(W)
Output power
VSy ISy cosφ
φ
Efficiency
(η
η)
O/p / I/p
×100
Watts
Watts
%
% Of
Regulation
VNL-VLOAD
VLOAD
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Model Graph
% Of Effeciency
% Of Regulation
Regulation
Effeciency
Output power in watts
RESULT
Thus the load test on a given single phase transformer is done and the characteristic curves are
drawn.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
OPEN CIRCUIT TEST AND SHORT CIRCUIT TEST
ON SINGLE PHASE TRANSFORMER
AIM
To Predetermine the Efficiency and Regulation on a given single phase transformer by
conducting the Open Circuit test and Short Circuit test and also draw its Equivalent circuit.
NAME PLATE DETAILS
FUSE RATING
Primary Current = KVA Rating of the Transformer / Primary Voltage.
Secondary Current = KVA Rating of the Transformer / Secondary Voltage.
10% of Primary current (fuse rating for Open Circuit test)
125% of Secondary current (fuse rating for Short circuit test)
APPARATUS REQUIRED
S.No
Name of the apparatus
Type
Range
Quantity
1
Ammeter
MI
(0-1A)
1
2
Ammeter
MI
(0-10A)
1
3
Voltmeter
MI
(0-150V)
1
4
Voltmeter
MI
(0-300V)
1
5
6
Watt meter
UPF
300V, 1A
1
Watt meter
UPF
75V, 5A
1
7
Auto Transformer
1φ
230/(0-270V)
1
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR OPEN CIRCUIT TEST ON SINGLE PHASE TRANSFORMER
(0-5A)
MI
A
P
A
SPSTS
150V, 5A LPF
M
L
Fuse
C
B
150V
P1
1Ø, 230V, 50Hz
AC SUPPLY
V
S1
(0-150V)
MI
V
(0-300V)
MI
P2
39
C
S2
NL
N
230/(0-270V)
1Ø AUTO
TRANSFORMER
Prepared by
1Ø 110/230V, 1KVA
STEP UP
TRANSFORMER
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR SHORT CIRCUIT TEST ON SINGLE PHASE TRANSFORMER
(0-5A)
300V, 10A UPF
MI
L
A M
A
P
SPSTS
A
Fuse
C
B
(0-10A)
MI
75V
P1
S1
1Ø, 230V, 50Hz
AC SUPPLY
V
(0-75V)
MI
SC
41
P2
S2
C
NL
N
230/(0-270V)
1Ø AUTO
TRANSFORMER
Prepared by
1Ø 230/110V, 1KVA
STEP DOWN
TRANSFORMER
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for OC and SC test on Single phase transformer
Open Circuit test
S.No.
Multiplication Factor =
Open Circuit
Primary
Current (IOC)
Amps
Open circuit
Primary
Voltage (VOC)
Volts
Open Circuit power (WOC)
Obs.
Act.
Watts
Watts
Open Circuit
secondary
Voltage (V2O)
Volts
Sh
ort
Circuit test
Multiplication Factor =
S.No.
Short Circuit
Primary
Current (ISC)
Amps
Short circuit
Primary
Voltage (VSC)
Volts
Short Circuit power (WSC)
Obs.
Act.
Watts
Watts
Short Circuit
secondary
Current (I2S)
Volts
Resultant Tabulation to find out the Efficiency
Core (Or) Iron Loss
=
Rated Short Circuit Current (ISC) =
Fraction of
Load (X)
Short
circuit
Current
(ISC×X)
Amps
A Rating of Transformer =
Short Circuit Power (WSC) =
Output power
0.2
0.4
0.6
Watts
0.8
1
Copper
Loss
(X2 WSC)
Total Loss
WT =
Wi+WSC
Efficiency
O/p
η= O/p+TL
Watts
Watts
%
1/4
1/2
3/4
1
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
FORMULAE
EQUIVALENT CIRCUIT
Open Circuit Test
Woc
1. No Load Power Factor (Cosφ
φo) = Voc × Ioc
Where, Woc – Open Circuit Power in Watts
Voc – Open Circuit Voltage in Volts
Ioc – Open Circuit Current in Amps
Voc
Ioc × Cosφo
2.No Load Working Component Resistance (Ro) =
in Ohms
Where Voc – Open Circuit Voltage in Volts.
Ioc – Open Circuit current in Amps.
Voc
3. No Load Magnetizing Component Reactance( Xo) = Ioc × Sinφ
in Ohms
o
Where Voc – Open Circuit Voltage in Volts.
Ioc – Open Circuit current in Amps.
Short Circuit Test
Vsc
Isc
4. Equivalent impedance referred to HV side ( Z02 ) =
in Ohms
Where, Vsc – Short circuit Voltage in Volts
Isc – Short circuit current in Amps
5. Equivalent resistance referred to HV side (R02 ) = Wsc2
in Ohms
Isc
Where, Wsc – Short circuit Power in Watts
6. Equivalent reactance referred to HV side (X02) =
Z022 - R022 in Ohms
V
7. Transformation ratio (K) = V2
1
Where, V1 – Primary voltage in Volts
V2 – Secondary Voltage in Volts
R02
K2
8. Equivalent resistance referred to LV side (R01) =
9. Equivalent reactance referred to LV side (X01) =
in Ohms
X02
K2
in Ohms
Efficiency and Regulation
10. Output Power = X ×KVA × cosφ in Watts.
Where, X-Fraction of load
KVA - power rating of Transformer and Cosφ - Power factor
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
11. Copper loss = X2 × Wsc in Watts
Where, Wsc- Copper Loss in Short Circuit condition
12. Total Loss = (Cu Loss + Iron Loss) in Watts
13. Efficiency =
Output power
(Output power +Total Losses)
14. Regulation =
x 100
X × Isc [R02 x cosφ ± X02 x sinφ]
V2o
in %
× 100 in %
Where, V2o – Open Circuit Voltage on HV side.
PRECAUTION
•
•
No Load Condition should be observed at the time of starting
Meters are checked for proper Type and rating.
PROCEDURE
OPEN CIRCUIT TEST
•
•
•
•
•
•
Connections are given as per the circuit diagram.
The SPST Switch on the Primary side is closed.
The Autotransformer is adjusted to Energize the transformer with rated Primary Voltage
on the LV side
The Volt meter, Watt meter and Ammeter Readings are noted at No load condition
The Autotransformer is brought to its initial position
The Supply is switched off.
SHORT CIRCUIT TEST
•
•
•
•
•
•
Connections are given as per the circuit diagram.
The SPST Switch on the Primary side is closed
The Autotransformer is adjusted to energize the transformer with rated Primary Current on
the HV side.
The Voltmeter, Wattmeter and Ammeter Readings are noted down at short circuit
condition.
The Autotransformer is brought to its initial position
The Supply is switched off.
GRAPH
The graph are drawn as
• Output power Vs Efficiency
• Output power Vs Regulation
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Resultant Tabulation to find out the Regulation
ISC =
Fraction
of Load
(X)
1
Prepared by
Value of Cosø
0.8
0.6
0.4
RO2 =
0.2
1
Value of Sinø
0.8
0.6
0.4
XO2 =
0.2
1
V2(OC) =
% Of Regulation
0.8
0.6
0.4
0.2
Lag. Lead. Lag. Lead. Lag. Lead. Lag. Lead.
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Equivalent circuit for Single phase Transformer
P
R01
I1
X01
I0
Iw
V1
I
R0
ZL
X0
N
Model Graph
1.0 pf
Regulation
X=1
0.8 pf
X =3/4
X =1/2
Effeciency
0.6 pf
X =1/4
0.4 pf
0.2 pf
Leading pf
Unity pf
Lagging pf
Short Circuit Current (ISC) in Amps
RESULT
Thus the efficiency and regulation of a given single phase transformer by conducing the open
circuit test and short circuit test is determined and the equivalent circuit is drawn.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
LOAD TEST ON THREE PHASE SQUIRREL CAGE
INDUCTION MOTOR
AIM
To conduct a load test on a three phase squirrel cage induction motor and to draw the
performance characteristic curves.
NAME PLATE DETAILS
!
"
"# $% "&'"
FUSE RATING
125% of rated current (Full load current)
APPARATUS REQUIRED
S.NO
NAME OF THE
APPARATUS
1.
2.
3.
4.
Ammeter
Voltmeter
Wattmeter
Tachometer
TYPE
RANGE
QUANTITY
MI
MI
UPF
(0-10 A)
(0-600 V)
(500V, 10A)
1
1
1
-
-
1
FORMULAE USED
1.Torque = (S1-S2) (R+t/2) x 9.81 N-m
Where, S1, S2 – spring balance readings in Kg.
R - Radius of brake drum in m.
t - Thickness of belt in m.
2. Output Power = 2 πNT/60 watts.
N- Rotor speed in rpm.
T- Torque in N-m.
3. Input Power = (W1+W2) Watts.
W1, W2 – Wattmeter readings in Watts.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR LOAD TEST ON THREE PHASE SQUIRRAL CAGE INDUCTION MOTOR
STAR-DELTA
STARTER
600V, 10A UPF
M
R
L
L1
Fuse
V
415V, 50Hz, 3Ø
AC SUPPLY
Y
T
P
S
T
S
A1
600V
C
C2
S1
(0-600) V
MI
R
A2
A2
A
Fuse
S2
A1
L2
B1
(0-10) A
MI
C1
BRAKE DRUM
B1
B2
STATOR
51
B2
C
600V
C1
B
Fuse
M
L
600V, 10A UPF
L3
C2
NL
N
Prepared by
N
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
4. Percentage of Efficiency = (Output Power/ Input Power) x 100%.
5. Percentage of Slip = (NS-Nr)/Ns x 100%
Ns-Synchronous speed in rpm.
Nr-Rotor speed in rpm.
6.Power factor = (W1+W2)/√3 VLIL.
PRECAUTION
The motor should be started without any load
PROCEDURE:
•
•
•
•
Connections are given as per the circuit diagram.
The TPSTS is closed and the motor is started using On Line starter to run at rated speed.
At no load the speed, current, voltage and power are noted down.
By applying the load for various values of current the above-mentioned readings are noted.
• The load is later released and the motor is switched off and the graph is drawn. .
GRAPH
The graph are drawn as
•
•
•
•
•
•
Output Power Vs Speed
Output Power Vs Line current
Output Power Vs Torque
Output Power Vs Power factor
Output Power Vs % Efficiency
Output Power Vs % Slip.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for load test on three phase squirrel cage induction motor
Multiplication Factor:
S.No
Load
Curren
t
(IL)
Amps
Prepared by
Load
Voltage
(VL)
W1
Obs.
Volts
Input
power
Wattmeter readings
W2
Act.
Obs.
Watts
Act.
Speed
of the
motor
(N)
W1+W2
Watts
rpm
Spring balance
reading
S1
S2
S1~S2
Kg
Kg
Kg
(S1~S2) (R+t/2)
(9.81)
Torque (T)
Output
power
2 NT/60
Efficiency
(η
η)
O/p / I/p
X100
N-m
Watts
%
G.Panneerselvam, Vel Tech Multi Tech
Power
Factor
(cosφ
φ)
I/p /
√3 VLIL
EC2259
Electrical Engineering And Control System Lab Manual
Load test on Three phase squirrel cage induction motor
Model Graphs:
(A) Mechanical characteristics
Torque Vs Speed
Speed in RPM
Torque in N-m
(B) Electrical characteristics:
Cos φ
N
IL
T
%
%
T in N-m
N in rpm
Cos φ
IL in Amps
O/P power in watts
RESULT
Thus the load test on a given three phase squirrel cage induction motor is done and the
characteristic curves are drawn.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
EQUIVALENT CIRCUIT OF THREE PHASE SQUIRREL CAGE
INDUCTION MOTOR
AIM
To conduct a No Load test and Blocked Rotor test on three phase squirrel cage induction motor
and to draw the equivalent circuit.
NAME PLATE DETAILS
!
"
"# $% "&'"
FUSE RATING
No Load: 10 % of rated current (Full load current)
Load: 125 % of rated current (Full load current)
APPARATUS REQUIRED
S.NO.
NAME OF THE
APPARATUS
Ammeter
Ammeter
Voltmeter
Voltmeter
Voltmeter
Wattmeter
Wattmeter
Tachometer
1.
2.
3.
4.
5.
6.
7.
TYPE
RANGE
QUANTITY
MC
MI
MI
MI
MC
LPF
UPF
-
(0-10 A)
(0-10 A)
(0-150 V)
(0-600 V)
(0-50 V)
(600V, 10A) (150V,
10A)
-
1
2
1
1
1
2
2
1
FORMULAE USED
OC Test
1. No load power factor (Cos φ0) = P0/V0I0
V0 - No load voltage per phase in volts.
I0 - No load current per phase in amps.
P0 - No load power per phase in watts.
2. Working component current (Iw) = I0 (ph) X Cos φ0
3. Magnetizing current (Im) = I0 (ph) X Sin φ0
4. No load resistance (R0) =V0/I0 (ph) Cos φ0 in Ω.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR NO LOAD TEST ON THREE PHASE SQUIRREL CAGE
INDUCTION MOTOR
(Equivalent circuit)
415 / (0-470) V
3Ø AUTO TRANSFORMER
600V, 10A LPF
A1
B1
R
M
L
A1
Fuse
600V
C
C1
415V, 50Hz, 3Ø
AC SUPPLY
Y
57
T
P
S
T
S
V
C2
(0-600) V
MI
R
A2
A2
B2
A
Fuse
C1
B1
(0-10) A
MI
B2
STATOR
C2
A3
C
600V
B3
B
M
L
600V, 10A LPF
Fuse
C3
N
Prepared by
NL
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR BLOCKED ROTOR TEST ON THREE PHASE SQUIRREL CAGE
INDUCTION MOTOR
(Equivalent circuit)
415 / (0-470) V
3Ø AUTO TRANSFORMER
150V, 10A UPF
A1
B1
R
M
L
A1
Fuse
415V, 50Hz, 3Ø
AC SUPPLY
Y
59
T
P
S
T
S
V
S1
150V
C
C1
C2
(0-150) V
MI
R
A2
A2
B2
A
Fuse
S2
C1
B1
BRAKE DRUM
B2
(0-10) A
MI
C2
STATOR
A3
C
150V
B3
B
M
L
150V, 10A UPF
Fuse
C3
N
Prepared by
NL
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for No Load test on three phase Squirrel cage Induction motor
Speed of the Induction motor:
Type of the Stator connection:
Multiplication Factor:
S.No
No Load
Current
(I0)
No Load
Voltage
(V0)
Amps
Volts
No Load Power
Total No Load Power
No Load Power/Phase
P0=(W1+W2)
P0 (Ph)=(P0/3)
Watts
Watts
W1
No Load
Current/Phase
I0 (Ph)
No Load
Voltage/Phase
V0 (Ph)
Amps
Volts
W2
Observed
Watts
Actual
Watts
Observed
Watts
Actual
Watts
Tabulation for Blocked rotor test on three phase Squirrel cage Induction motor
Type of the Stator connection:
Multiplication Factor:
S.No
Short
Circuit
Current
(ISC)
Amps
Prepared by
Short
Circuit
Voltage
(VSC)
Volts
Short Circuit Power
W1
Observed
Watts
W2
Actual
Watts
Observed
Watts
Actual
Watts
Total Short
Circuit Power
PSC=(W1+W
2)
Short Circuit
Power/Phase
PSC
(Ph)=(P0/3)
Short Circuit
Current/Phase
ISC (Ph)
Short Circuit
Voltage/Phase
VSC (Ph)
Watts
Watts
Amps
Volts
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
5. No load reactance (X0) = V0/I0 (ph) Sin φ0 in Ω.
SC Test
6. Motor equivalent Impedance referred to stator (Zsc(ph)) = Vsc(ph) / Isc(ph) in Ω.
7. Motor equivalent Resistance referred to stator (Rsc(ph)) = Psc(ph) / I2sc(ph) in Ω.
8. Motor equivalent Reactance referred to stator (Xsc(ph)) = √(Z sc(ph)2- R sc(ph)2) in Ω.
9. Rotor Resistance referred to stator (R2’(ph)) = Rsc(ph) – R1 in Ω.
10. Rotor Reactance referred to stator (X2’(ph)) = Xsc(ph) / 2 = X1 in Ω.
Where R1 - stator resistance per phase
X1 – stator reactance per chapter
R1 = R(ac) =1.6 x R(dc)
11. Equivalent load resistance (RL’) = R2’ (1/s – 1) in Ω.
Where Slip (S) = (Ns-Nr) / Ns
Ns – Synchronous speed in rpm.
Nr – Rotor speed in rpm.
PRECAUTION
•
The autotransformer should be kept at minimum voltage position
PROCEDURE
•
Connections are given as per the circuit diagram.
•
For No-Load or open circuit test by adjusting autotransformer, apply rated voltage and
•
Note down the ammeter and wattmeter readings. In this test rotor is free to rotate.
•
For short circuit or blocked rotor test by adjusting autotransformer, apply rated current
and note down the voltmeter and wattmeter readings. In this test rotor is blocked.
•
After that make the connection to measure the stator resistance as per the circuit diagram.
•
By adding the load through the loading rheostat note down the ammeter, voltmeter
reading for various values of load.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Equivalent circuit for three phase squirrel cage induction motor
P
R1
R2'
X1
X2'
I0
Iw
1Ø, 230V, 50Hz AC
Supply
R0
I
X0
RL' =R2' (1/s-1)
N
RESULT
Thus the no load and blocked rotor test on a given three phase squirrel cage induction motor and
the equivalent circuit is drawn.
Prepared by
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EC2259
Electrical Engineering And Control System Lab Manual
REGULATION OF THREE PHASE ALTERNATOR BY EMF AND MMF
METHODS.
AIM
To predetermine the regulation of a given three phase Alternator by EMF and MMF method and also draw the
vector diagrams.
NAME PLATE DETAILS
( '" #
"
)
"
FUSE RATING
125% of rated current (Full load current)
For DC shunt motor:
For Alternator:
APPARATUS REQUIRED
S.NO.
1.
2.
3.
4.
5.
6.
7.
8.
Prepared by
NAME OF THE
APPARATUS
Ammeter
Ammeter
Ammeter
Voltmeter
Voltmeter
Rheostat
Rheostat
Tachometer
TYPE
RANGE
QUANTITY
MC
MC
MI
MI
MC
Wire Wound
Wire Wound
-
(0-2 A)
(0-10 A)
(0-10 A)
(0-600V)
(0-50V)
(500Ω, 1.2A)
(300Ω, 1.7A)
-
1
1
1
1
1
2
1
1
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR REGULATION OF THREE PHASE ALTERNATOR
BY EMF & MMF METHOD
(Open circuit and Short circuit tests)
3 POINT STARTER
L
F A
A
Fuse
250 , 2A
220V DC
SUPPLY
D
P
S
T
S
F
A
M
R
V (0-600) V
MI
N
B
X
FF
Fuse
Y
XX
AA
T
P
S
T
S
(0-10) A
MI
Fuse
(0-2) A
A
79
Fuse
220V
DC SUPPLY
D
P
S
T
S
MC
Fuse
Fuse
350 , 1.5A
Fuse
Prepared by
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Electrical Engineering And Control System Lab Manual
FORMULAE USED
EMF Method
1. Armature Resistance Ra = 1.6 Rdc in ohms.
Here, Rdc is the resistance in DC supply.
2. Synchronous impedance Zs =
Open circuit voltage (E1 (ph))
Short circuit current (Isc)
(from the graph)
3. Synchronous impedance Xs = (Zs² - Ra²) in ohms.
4. Open circuit voltage
Eo= (V cosø + Isc Ra) ² + (V sinø - Isc Xs) ² in Volts.
(For lagging power factor)
5. Open circuit voltage
Eo= (V cosø + Isc Ra) ² + (V sinø - Isc Xs) ² in Volts
(For leading power factor)
7. Open circuit voltage
Eo= (V + Isc Ra) ² + (Isc Xs) ² in Volts
(For Unity power factor)
6. Percentage regulation
=
Eo –Vrated
Vrated
X 100
(both for EMF & MMF method)
PRECAUTION
•
•
•
The motor field rheostat should be kept in the minimum resistance position.
The Alternator field Potential divider should be in the maximum voltage position.
Initially all Switches are in open position.
PROCEDURE FOR BOTH EMF AND MMF METHOD
•
•
•
•
•
•
Connections are made as per the circuit diagram.
Give the supply by closing the DPST Switch.
Using the Three Point starter, start the motor to run at the synchronous speed by varying the
motor field rheostat.
Conduct an Open Circuit Test by varying the Potential Divider for various values of Field
Current and tabulate the corresponding Open Circuit Voltage readings.
Conduct a Short Circuit Test by closing the TPST switch and adjust the potential divider to
set the rated Armature Current, tabulate the corresponding Field Current.
Conduct a Stator Resistance Test by giving connection as per the circuit diagram and
tabulate the Voltage and Current readings for various resistive loads.
Prepared by
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Electrical Engineering And Control System Lab Manual
PROCEDURE TO DRAW THE GRAPH FOR EMF METHOD
•
•
•
Draw the Open Circuit Characteristics curve (Generated Voltage per phase Vs Field Current).
Draw the Short Circuit Characteristics curve (Short Circuit Current Vs Field Current).
From the graph find the open circuit voltage per phase (E1 (Ph)) for the rated Short Circuit Current
(Isc).
• By using respective formulae find the Zs, Xs, Eo and percentage Regulation.
PROCEDURE TO DRAW THE GRAPH FOR MMF METHOD
•
•
•
•
•
•
Draw the Open Circuit Characteristics curve (Generated Voltage per phase Vs Field Current).
Draw the Short Circuit Characteristics curve (Short Circuit Current Vs Field Current).
Draw the line OL to represent If' which gives the rated generated voltage (V).
Draw the line LA at an angle (90 ± ) to represent If'' which gives the rated full load current (Isc)
on short circuit ((90 + ) for lagging power factor and (90- ) for leading power factor).
Join the points O and A and find the field current (If) by measuring the distance OA that gives the
Open Circuit Voltage (Eo) from the Open Circuit Characteristics.
Find the percentage Regulation by using suitable formula.
Tabulation for Regulation of three phase Alternator by EMF and MMF methods
Open circuit test
S.No.
Prepared by
Field Current
(If)
Open Circuit Line
Voltage (V0L)
Open Circuit Phase
Voltage (V0 (Ph))
Amps
Volts
Volts
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Short circuit test
S.No.
Field Current
(If)
Amps
Short Circuit Current
(120 to 150 % of rated current)
(ISC)
Amps
Regulation of three phase Alternator by EMF and MMF methods
Model Graph for EMF Method
OCC
Open Circuit Voltage (V0 (Ph)) in Volts
Short Circuit Current (ISC) in Amps
E1 (ph)
SCC
Field Current (If ) in Amps
Prepared by
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Electrical Engineering And Control System Lab Manual
Regulation of three phase Alternator by EMF and MMF methods
Model Graph for MMF Method
E0 (ph)
Lag.
E0 (ph)
Unity
OCC
SCC
E0 (ph)
Open Circuit Voltage (V0 (Ph)) in Volts
Short Circuit Current (ISC) in Amps
Lead.
Unity
A
A
Lead.
90-
O
Prepared by
Lag.
A
90+
L
Field Current (If ) in Amps
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Resultant Tabulation for Regulation of three phase Alternator by EMF and MMF
methods
Percentage of Regulation
S.No.
Power
Factor
Lagging
EMF Method
Leading
Unity
Lagging
MMF Method
Leading
Unity
1.
0.2
-
-
2.
0.4
-
-
3.
0.6
-
-
4.
0.8
-
-
5.
1.0
+ % Regulation
Regulation curve of Alternator (EMF, MMF and Vector diagram)
From EMF method
From MMF method
Lagging pf
Leading pf
- % Regulation
Unity pf
RESULT
Thus the regulation of three phase alternator by EMF and MMF methods and the regulation curves are
drawn.
Prepared by
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EC2259
Electrical Engineering And Control System Lab Manual
STABILITY ANALYSIS OF LINEAR SYSTEM
AIM
To analysis the stability of the given linear system using Bode Plot, Nyquist Plot and Root Locus.
APPRATUS REQUIRED
S.No
Name of the apparatus
Type
Range
Quantity
1
Computer
-
-
1
2
MATLAB Software
-
-
1
THEORY
POLAR PLOT
The polar plot of a sinusoidal transfer function G ( jω ) on polar coordinates as ω is varied from zero to
infinity. Thus the polar plot is the locus of vectors G ( jw) and G ( jw) as ω is varied from zero to infinity. The
polar plot is also called Nyquist plot.
NYQUIST STABILITY CRITERION
If G ( s ) H ( s ) contour in the G ( s ) H ( s ) plane corresponding to Nyquist contour in s-plane encircles the
point −1 + j 0 in the anti – clockwise direction as many times as the number of right half s-plane of G ( s ) H ( s ) .
Then the closed loop system is stable.
ROOT LOCUS
The root locus technique is a powerful tool for adjusting the location of closed loop poles to achieve
the desired system performance by varying one or more system parameters.
The path taken by the roots of the characteristics equation when open loop gain K is varied from 0 to
∞ are
called root loci (or the path taken by a root of characteristic equation when open loop gain K is varied
from 0 to ∞ is called root locus.)
FREQUENCY DOMAIN SPECIFICATIONS
The performance and characteristics of a system in frequency domain are measured in term of frequency
domain specifications. The requirements of a system to be designed are usually specified in terms of these
specifications.
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Electrical Engineering And Control System Lab Manual
The frequency domain specifications are
1. Resonant peak M r .
2. Resonant Frequency ωr .
3. Bandwidth.
4. Cut – off rate
5. Gain margin
6. Phase margin
RESONANT PEAK M r
The maximum value of the magnitude of closed loop transfer function is called the resonant peak M r . A large
resonant peak corresponds to a large over shoot in transient response.
RESONANT FREQUENCY ωr
The bandwidth is the range of frequency for which the system gain is more than −3 dB . The frequency at
which the gain is −3 dB , called cut off frequency. Bandwidth is usually defined for closed loop system and it
transmits the signals whose frequencies are less than cut-off frequency. The bandwidth is a measured of the
ability of a feedback system to produce the input signal, noise rejection characteristics and rise time. A large
bandwidth corresponds to a small rise time or fast response.
CUT-OFF RATE
The slope of the log-magnitude curve near the cut off frequency is called cut-off rate. The cut-off rate
indicates the ability of the system to distinguish the signal from noise.
GAIN MARGIN K g
The gain margin K g is defined as the reciprocal of the magnitude of open loop transfer function at phase cross
over frequency. The frequency at witch the phase of open loop transfer function is 180 is called the phase
cross over frequency ω pc .
PHASE MARGIN γ
The phase margin γ is that amount of additional phase lag at the gain cross over frequency required to bring
the system to the verge of instability, the gain cross over frequency ω gc is the frequency at which the
magnitude of open loop transfer function is unity (or it is the frequency at which the db magnitude is zero).
Prepared by
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Electrical Engineering And Control System Lab Manual
PROCEDURE
• Enter the command window of the MATLAB.
•
Create a new M – file by selecting File – New – M – File.
•
Type and save the program.
•
Execute the program by either pressing F5 or Debug – Run.
•
View the results.
•
Analysis the stability of the system for various values of gain.
PROBLEM
Obtain the Bode Plot, Nyquist Plot and Root Locus of the given open loop T.F is H ( s ) =
2
2
s + 3s + 2
Using Bode Plot
num = [0 0 2]
den = [1 3 2]
bode (num,den)
grid
title (‘BODE DIAGRAM’)
% To Find out Gain Margin
sys = tf (num, den)
bode (sys)
Margin (sys)
[ gm, ph, wpc, wgc ] = margin (sys).
Using Nyquist Plot
num = [0 0 2]
den = [1 3 2]
nyquist (num,den)
grid
title (‘Nyquist Plot’)
Using Nyquist Plot
num = [0 0 2]
den = [1 3 2]
rlocus (num,den)
grid
title (‘Root Locus Plot’)
RESULT
Thus the stability of the given linear system using Bode Plot, Nyquist Plot and Root Locus was
analyzed.
Prepared by
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Electrical Engineering And Control System Lab Manual
DIGITAL SIMULATION OF LINEAR SYSTEM
AIM
To simulate the time response characteristics of second order linear system using
MATLAB.
APPRATUS REQUIRED
S.No
Name of the apparatus
Type
Range
Quantity
1
Personal Computer
-
-
1
2
MATLAB Software
-
-
1
THEORY
The desired performance characteristics of control system are specified in terms of time
domain specification. Systems with energy storage elements cannot respond instantaneously and
will exhibit transient responses, whenever they are subjected to inputs or disturbances.
The desired performance characteristics of a system pf any order may be specified in
terms of the transient response to a unit step input signal.
The transient response of a system to unit step input depends on the initial conditions.
Therefore to compare the time response of various systems it is necessary to start with standard
initial conditions. The most practical standard is to start with the system at rest and output and
all time derivatives there of zero. The transient response of a practical control system often
exhibits damped oscillations before reaching steady state.
The transient response characteristics of a control system to a unit step input are
specified in terms of the following time domain specifications.
1. Delay time td
2. Rise time tr
3. Peak time t p
4. Maximum overshoot M p
5. Settling time t s
1. Delay Time
It is the taken for response to reach 50% of the final value, for the very first time.
Prepared by
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Electrical Engineering And Control System Lab Manual
2. Rise Time
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 raise from 10% to 90%. For critically damped system, it is the
time taken for response to raise from 5% to 95%.
Rise time tr
=
π −θ
ωd
Where, θ
= tan
1−ξ 2
−1
ξ
and
Damped frequency of oscillation ωd = ωn
1−ξ 2
3. Peak Time
It is the time taken for the response to reach the peak value for the very first time. (or) It is the
taken for the response to reach the peak overshoot t p .
Rise time t p
=
π
ωd
4. Peak Overshoot (Mp)
It is defined as the ration of the maximum peak value measured from final value to the final
value.
Let final value = c (e)
Maximum vale = c (t p )
Peak Overshoot, M p =
c (t p ) − c ( e )
c (e)
−πξ
%M p = e
1−ξ 2
× 100
5. Settling Time
It is defined as the time taken by the response to reach and stay within a specified error. It is
usually expressed as % of final value. The usual tolerable error is 2% or 5% of the final value.
Prepared by
Settling Time t s
=
Settling Time t s
=
4
ξωn
3
ξωn
(For 2% error).
(For 5% error).
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
PROCEDURE
•
Enter the command window of the MATLAB.
•
Create a new M – file by selecting File – New – M – File.
•
Type and save the program.
•
Execute the program by either pressing F5 or Debug – Run.
•
View the results.
•
Analysis the time domain specifications of the system.
PROBLEM
Obtain the time domain specifications of the given open loop T.F is H ( s ) =
100
2
s + 2 s + 100
MATLAB PROGRAM FOR UNIT IMPULSE PRSPONSE
num = [ 0 0 100 ]
den = [ 1 2 100 ]
impulse (num, den)
grid
title (‘ unit impulse response plot’)
MATLAB PROGRAM FOR UNIT STEP PRSPONSE
num = [ 0 0 100 ]
den = [ 1 2 100 ]
step (num, den)
grid on
title (‘unit step response plot’)
RESULT
Thus the time response characteristic of second order linear system was verified using
MATLAB.
Prepared by
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Electrical Engineering And Control System Lab Manual
DESIGN OF P, PI, PID CONTROLLER
AIM
To design P, PI, and PID controllers for first order systems using MATLAB.
APPARATUS REQUIRED
1. Controller and system kit.
2. Patch chords.
3. Computer and Interference chord.
THEORY
Proportional Controller
1. The Proportional Controller is a device that produces the control signal, u (t) which is
Proportional to the input error signal e (t).
In P – controller, u (t) e (t).
Therefore u (t) = Kp c (t).
Where Kp – Proportional gain or constant.
2. The Proportional plus Integral Controller (PI – Controller) produces an output signal
consisting of two terms one on proportional to error signal and the other proportional to
the integral of error signal
In PI – Controller, u (t)
[e (t) + | e (t) dt]
Therefore, u (t) = e (t) + Kp / Ti | e (t) dt
Where Kp – Proportional gain or constant,
Ti – Integral Time.
3. The PID Controller produces an output signal consisting of three terms one on
proportional to error signal and the another one proportional to the integral of error
signal and the third one is proportional to derivative of error signal.
In PID Controller, u (t) [e (t) + | e (t) + d /dt ((e (t))]
Therefore, u (t) = e (t) + Kp / Ti | e (t) dt + Kp Td d /dt ((e(t))]
Where Kp – Proportional gain or constant,
Ti – Integral Time.
Td – Derivative Time.
Prepared by
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Electrical Engineering And Control System Lab Manual
Type 0 First Order System with P – Controller
Step Input
(FG)
P Controller
Level Shifter
Computer CH 0
Level Shifter
Computer CH 1
EC2259
Electrical Engineering And Control System Lab Manual
Type 0 First Order System with PI - Controller
Step Input
(FG)
PI Controller
Level Shifter
Computer CH 0
Level Shifter
Computer CH 1
EC2259
Electrical Engineering And Control System Lab Manual
Type 0 First Order System with PID - Controller
Step Input
(FG)
PID Controller
Level Shifter
Computer CH 0
Level Shifter
Computer CH 1
EC2259
Electrical Engineering And Control System Lab Manual
Procedure
Type – 0 First Order System with P – Controller
1. Connections are given as per the circuit diagram.
2. Set Proportional Band = 80, Integral Time = 64000 and Derivative Time = 0.
3. Measure the performance specifications.
Type – 0 First Order System with PI – Controller
1. Connections are given as per the circuit diagram.
2. Set Proportional Band = 80, Integral Time = 30 and Derivative Time = 0.
3. Measure the performance specifications.
Type – 0 First Order System with PI – Controller
1. Connections are given as per the circuit diagram.
2. Set Proportional Band = 80, Integral Time = 30 and Derivative Time = 0.1.
3. Measure the performance specifications.
Transfer Function for P, PI, and PID Controller:
P – Controller:
Transfer Function = Kp
PI – Controller:
Transfer Function = Kp [1 + 1 / Ti S]
PID Controller:
Transfer Function = Kp [1 + 1 / Ti S + Td S]
TABULAR COLUMN
S. No
Time Domain Specification
Prepared by
P controller
PI controller
PID controller
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Model Graph
RESULT
Thus the design of P, PI and PID controller was done.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
DESIGN OF LAG AND LEAD COMPENSATOR
AIM
To design and implement the suitable lag and lead compensator for a given linear system
to improve the performance.
APPARATUS REQUIRED
1.
Transfer function and compensator
2.
Computer interface chord
3.
Patch chords
THEORY
LAG COMPENSATOR
A compensator having the characteristics of a Lag network is called a lag
compensator. If a sinusoidal signal is applied to a lag network, then in steady state the output
will have a phase lag with respect to input.
Lag compensation results in a large improvement in steady state performance but
results in slower response due to reduced bandwidth. The attenuation due to the lag compensator
will shift the gain cross over frequency to a lower frequency point where the phase margin is
acceptable.
The general form of lag compensator transfer function is given by:
G(S) = (S+T) / (S+P) = (S + 1/T) / S + 1/BT
Where, T > 0 and B >1
LEAD COMPENSATOR
A compensator having the characteristics of a Lead network is called a Lead
compensator. If a sinusoidal signal is applied to the lead network, then in steady state the output
will have a phase lead with respect to input.
Lead compensation increases the bandwidth, which improves the speed of
response and also reduces, whereas there is a small change in steady state accuracy. Generally,
Lead compensation is provided to make an unstable system as a stable system.
A Lead compensator is basically a high pass filter so it attenuates high frequency
noise effects. If the pole introduced by the compensator is not cancelled by a zero in the system,
then lead compensation increases the order of the system by one.
The general form of Lead compensator transfer function is given by:
G(S) = (S+T) / (S+P) = (S + 1/T) / S + 1/aT
Where, T > 0 and a<1
PROCEDURE
Prepared by
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EC2259
Electrical Engineering And Control System Lab Manual
Type II Order System Performance
Without Lag Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%
5. Measure the time domain specification of the II order system from the waveform.
With Lag Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%
5. Measure the time domain specification of the II order system from the waveform.
6. Compare the performance with and without lag compensator.
TABULAR COLUMN
S. No
Time Domain Specification
Without Lag
With Lag
PROCEDURE
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Electrical Engineering And Control System Lab Manual
Type II Order System Performance
Without Lead Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%.
5. Measure the time domain specification of the I order system from the waveform.
With Lead Compensator
1. Connections are given as per the circuit diagram.
2. Switch on the power supply.
3. Apply step input.
4. Set Pb = 100%
5. Measure the time domain specification of the I order system from the waveform.
6. Compare the performance with and without Lead compensator.
TABULAR COLUMN
S. No
Time Domain Specification
Prepared by
Without Lead
With Lead
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Model Graph (Lead Compensator)
Model Graph (Lead Compensator)
RESULT: Thus the lag and lead compensator of the given system is implemented and the
performance was compared.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
TRANSFER FUNCTION OF SEPARATELY EXCITED
DC SHUNT GENERATOR
AIM
To determine the transfer function of the given Separately Excited DC Shunt generator.
NAME PLATE DETAILS
FUSE RATING
Motor: 125% of full load current (rated current)
Generator: 125% of full load current (rated current)
APPARATUS REQUIRED
S.No
Name of the apparatus
Type
Range
Quantity
1
Ammeter
MC
(0-10A)
1
2
Ammeter
MC
(0-2A)
1
3
Ammeter
MI
(0-300mA)
1
4
Voltmeter
MC
(0-300V)
1
5
Voltmeter
MI
(0-300V)
1
6
Rheostat
Wire wound
250 , 2A
1
7
Rheostat
Wire wound
350 , 1.5A
1
8
Single Phase Variac
-
230V/ (0-270V)
1
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Electrical Engineering And Control System Lab Manual
FORMULAE
1.Generated EMF Constant (Kg) = Eg / If in Volts / Amps (From the Graphs)
2. Field Resistance (Rf) = Vf / If
3. Effective Resistance (Reff) =
VL/
IL in Volts / Amps (From the Graphs)
Where, VL = Change in load voltage in volts
IL
= Change in load current in amps
4. Load Resistance (RL) = PL / IL 2
Where, RL = Load Resistance in Ohms
PL
= Power of Load in Watts
IL = Total Load current in Amps
5. Field Inductance Lf
Where, Xf=
2
2
(Zf –Rf )
Xf= 2 f Lf
Lf= Xf / 2 f
f = frequency of applied source in hertz
6.Transfer function
Eg(s) Ef(s) =
(Kg / Rf )
(No Load)
(1+ (Lf/Rf) S)
(Kg / Rf )
Vt (s) / Ef(s) =
(1+ (Lf / Rf) S) (1+ (Reff / RL))
(Load)
PRECAUTION
1. The motor field rheostat should be kept at minimum resistance position.
2. The motor armature rheostat should be kept at maximum resistance position.
3. At the time of starting, the motor should be in no load condition.
Prepared by
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Electrical Engineering And Control System Lab Manual
PROCEDURE
To find out Generated EMF Constant (Kg)
1. Connections are given as per the circuit diagram.
2. The motor is made to run at the rated speed.
3. The generated emf is noted for various values of field current.
4. The voltage across the field winding is also measured
5. From the OCC curve Back Emf constant is calculated.
To find out Field Impedance (Zf)
1. Connections are given as per the circuit diagram.
2. Using single phase variac the supply voltage is varied.
3. The corresponding reading of field current is noted for different values of applied voltage.
4. From the noted readings the field Impedance is calculated.
RESULT
Thus the transfer function of separately excited DC shunt generator is determined.
Prepared by
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EC2259
Electrical Engineering And Control System Lab Manual
TRANSFER FUNCTION OF ARMATURE AND FIELD
CONTROLLED DC SHUNT MOTOR
AIM
To determine the transfer function of the given armature and field controlled DC shunt
motor.
NAME PLATE DETAILS
FUSE RATING:
125% of rated current (full load current)
APPRATUS REQUIRED
S.No
Name of the apparatus
Type
Range
Quantity
1
Ammeter
MC
(0-15A)
1
2
Ammeter
MC
(0-2A)
1
3
Ammeter
MI
(0-10A)
1
4
Voltmeter
MC
(0-300V)
1
5
Voltmeter
MC
(0-50V)
1
6
Voltmeter
MI
(0-300V)
1
7
Rheostat
Wire wound
250 , 2A
8
Rheostat
Wire wound
50 , 5A
1
9
Rheostat
Loading
10A, 230V
1
10
Tachometer
Digital
-
1
11
Single Phase Variac
-
230V / (0-270V)
1
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
FORMULAE
1. Inertia Constant (J) ={{(Vav * Iav) / (Nav * N)}×(60/2 ) 2 ×((t1* t2) /(t1-t2))} Kg-m2
(V1+V2) / 2
Where, Vav
Iav
(I1+I2) / 2
Nav
N
(N1+N2) / 2
Small Change in Speed (i.e) N1~N2
t1
Time for fall of speed from 1500 rpm to 750 rpm in no load condition
in seconds.
t2
Time for fall of speed from 1500rpm to 750rpm in load condition in
Seconds
2. Viscous Friction Co-Efficient (f) =(2 /60) 2 ×(J / 2) ×(N12~N22) in N-m / rad /Sec
Where, J
Inertia Constant in Kg-m2
Angular displacement in rad / Sec
= (2 Nav /60)
3. Back EMF Constant (Kb) =(Va-IaRa) / (2 N/60) in N-m / Amps
4. Torque T = (S1~S2) × (R+ t/2) × 9.81 in N-m.
Where, R- Radius of the Break drum in m.
t- Thickness of the Belt in m.
S1, S2- Spring balance reading in Kg.
5. Motor Gain Constant (Km) = KT / (Ra × f )
Where KT = KT' × (Current through the Armature / Rated Current of the Motor)
KT'= T / Ia (From the Graphs)
6. Motor Time Constant ( a) = La / Ra.
2
2
Where, Xa= (Za -Ra )
Xa= 2 f La
La= Xa / 2 f
7. Transfer function Q(s) / E(s) =
[KT / (Ra × f )]
S{ [1+ (La/Ra) S] [1+ (J/f) S]+ [KT Kb /(Ra × f)]}
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
THEORY
Ra = Armature resistance in ohms.
La= Armature inductance of the winding in Henry.
Ia= Armature current in Amps.
If = Field current in Amps
E= Applied voltage in Volts.
Eb=Backemf in Volts.
Tm =Torque developed by the motor in N-m
=Angular displacement of motor shaft in radian.
J= Equivalent of moment of inertia of motor and load referred to motor shaft in kg-m2
f=Equivalent viscous friction coefficient of motor and load referred to motor shaft in
N-m / rad / Sec.
Air gap flux is proportional to the field current because the DC motor should operate
in linear magnetization curve for servo application.
(i.e)
If
Kf If
Where, Kf is the Proportionality constant
The torque developed by the motor is proportional to the product of armature current
and air gap flux.
(i.e) Tm
Ia
Ia Kf If
= K1 Ia Kf If
We know that If is constant for armature controlled motor.
(i.e) Tm =
Tm =
(K1 Kf If ) Ia
KT Ia
Where, KT is the motor torque constant
Back emf of the emf of motor is proportional to the speed.
(i.e) Eb
Prepared by
d ( )/ dt
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
Eb = Kb d ( )/ dt ------------------------- 1
Where, Kb is the back emf constant in volt / rad /sec
Loop equation of armature circuit
Va = La d (Ia)/dt +RaIa+Eb ------------------ 2
Torque equation is
J d2 /dt2 +f d /dt = Tm
= KT Ia --------------3
Taking Laplace transform of Equations 1,2, & 3
From Eq (1)
From Eq (2)
From Eq (3)
Eb(s) = Kb S (s)------------ 4
La S Ia(s) +Ra Ia(s) =
V(s) - Eb(s)
(La S +Ra) Ia (s)
= (V(s) - Kb S (s))
Ia (s)
= {(V(s) - Kb S (s) / (La S +Ra)}
J S2 (s) +f S (s)
=
Tm(s)
(J S2 +f S) (s)
=
Tm(s) = KT× Ia (s)
(J S2 +f S) (s)
=
KT× Ia (s)
(J S2 +f S) (s)
=
KT× {(E(s) - Kb S (s) / (La S +Ra)}
(JS2 +f S) (s)
=
KT E(s)
(La S +Ra)
(JS2 +f S) (s) + KT Kb S (s)
(La S +Ra)
Prepared by
=
-
KTKb S (s)
(La S +Ra)
KT E(s)
(La S +Ra)
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
{(JS2 +f S) (La S +Ra) + KT Kb S} (s)
=
KT E(s)
(La S +Ra)
(s)
=
=
E(s)
(s)
KT
S {(JS +f ) (La S +Ra) + KT Kb }
=
E(s)
(s)
KT
{(JS2 +f S) (La S +Ra) + KT Kb S}
E(s)
(s)
(La S +Ra)
KT
S {f Ra (1+(J/f) S) (1+(La/ Ra )S ) + KT Kb }
=
E(s)
KT / f Ra
S {(1+(J/f) S) (1+(La/ Ra) S) + KT Kb/ f Ra}
PRECAUTION
1. The motor field rheostat should be kept at minimum resistance position.
2. The motor armature rheostat should be kept at maximum resistance position.
3. At the time of starting, the motor should be in no load condition.
PROCEDURE
To find out Inertia Constant (J)
1. Connections are given as per the circuit diagram.
2. The DC supply is given by closing the DPST switch.
3. The DPDT switch is thrown into position 1,2.
4. The motor is made to run at the rated speed by adjusting the field rheostat.
5. The DPDT switch is brought to the original position 0,0’. The time taken for falling of
speed from 1500 to 750 rpm is noted.
6. Once again the DPDT switch is thrown into position 1,2. Then the motor is made to run at
the rated speed
7. Then the DPDT switch is changed into position 1’, 2’.
8. Then J and f is calculated by using the formula.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech
EC2259
Electrical Engineering And Control System Lab Manual
To find out Torque Constant (KT)
1. Connections are given as per the circuit diagram.
2. The DC supply is given by closing the DPST switch.
3. The field current is kept constant.
4. The motor is made to run at the rated speed.
5. The various values of Ia spring balance readings are noted
6. Torque is calculated and plotted from the graph by adjusting the slope, torque constant KT is determined.
To find out Back Emf Constant (Kb)
1.Connections are given as per the circuit diagram.
2. The motor is made to run at the rated speed.
3. At rated speed the supply voltage and armature value readings are noted.
4. The Back Emf constant is calculated.
To find out Armature resistance (Ra)
1. Connections are given as per the circuit diagram.
2. The DC supply is given by closing the DPST switch.
3. By adjusting the loading rheostat the various values of Ia and Va are noted.
4. The armature resistance is calculated by the application of formula.
To find out Armature inductance (La)
1. Connections are given as per the circuit diagram.
2. Using single phase variac the supply voltage is varied.
3. The corresponding reading of Ia are noted for different values of applied voltage
4. Then Za and La are calculated by using the formula.
RESULT
Thus the transfer function of the given armature and field controlled DC shunt motor is determined.
Prepared by
G.Panneerselvam, Vel Tech Multi Tech