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 singlephase transformer and open circuit and short circuit test on singlephase 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 autotransformer Resistive load
Regulation of threephase 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 threephase 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 autotransformer
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 Stardelta starter DOL starter Three phase autotransformer
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
! "
#
"
#
%
$ &
'
*
'
(
(
) )
+
, , / ' 
.
0
, )
(
) 2
%
%2 '
! $ &
'
)
1 ' 34
%
3)
%
)
%
% '
(5 (5 (
'
' 3
) )
) % "
# 3
)
3
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
(020A)
1
2
Voltmeter
MC
(0300V)
1
3
Rheostat
Wire wound
250 , 2A
1
4
Tachometer
Digital
FORMULAE 1. Torque T = (S1~S2) × (R+t/2) × 9.81 in Nm. 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 Nm. 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 (020A) MC
3 POINT STARTER
L
F A
A
Fuse 250 , 2A 220V DC SUPPLY
A
F
D P S T S
V
(0300V) MC
S1
S2
M AA
FF
BRAKE DRUM
Fuse
Model Graph (A) Electrical characteristics
N
(B) Mechanical characteristics
T %
T in Nm N in rpm
Speed in rpm
Torque Vs Speed
Torque in Nm IL in Amps (C) Torque, Speed Vs Load Current
Output power in watts
Torque in Nm
%
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 threepoint 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
Nm
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
(02A)
1
2
Ammeter
MC
(010A)
1
3
Voltmeter
MC
(0300V)
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 (010A) MC 3 POINT STARTER
L
A
F A 50 , 5A
Fuse
A D P S T S
220V DC SUPPLY
250 , 2A
(02A) MC
A
F
M FF
AA
Fuse
Tabulation for Speed control of DC Shunt motor Armature Control Method
Field Current:
S.No.
Field Control Method
Armature Current:
Armature Voltage (Va)
Speed (N)
Field Current (If)
Speed (N)
Volts
RPM
Amps
RPM
V
(0300V) MC
EC2259
Electrical Engineering And Control System Lab Manual
Model Graph (A) Armature Control Method:
Armature Voltage in Volts
Field Current Vs Speed
Speed in rpm
Speed in rpm
Armature Voltage Vs Speed
(B) Field Control Method:
Field Current in Amps
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.
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
(02A)
1
2
Ammeter
MC
(010A)
1
3
Voltmeter
MC
0300V
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 (010A) MC
3 POINT STARTER
L
A
F A
Fuse
A 250 , 2A
220V DC SUPPLY
D P S T S
V
(02A) MC
A
F
(0300V) 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 = VI0Ia0 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 IoIao2Ra) 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
(02A)
1
2
Ammeter
MC
(020A)
2
3
Voltmeter
MC
(0300V)
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
A
17
Fuse
(020A) MC
F
M FF
A
(02A) MC
AA
G AA
A
A
1050 , 1.5A
L
(0300V) MC
Fuse
V
D P S T S
(020A) MC
L O A D
FF
Fuse
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
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 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 self excited DC generator and the characteristic curves are drawn.
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
(02A)
1
2
Ammeter
MC
(020A)
2
3
Voltmeter
MC
(0300V)
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 SEPERATELY EXCITED DC GENERATOR (020A) 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
(0300V) MC
G
V
F
FF
Fuse
AA
D P S T S
L O A D
(02A)
A
MC
23 Fuse
220V DC SUPPLY
D P S T S
Fuse
Fuse
350 , 1.5A
Fuse
(020A) MC
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
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.
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
(05A)
1
2
Ammeter
MI
(020A)
1
3
Voltmeter
MI
(0150V)
1
4
Voltmeter
MI
(0300V)
1
5 6
Watt meter
UPF
300V, 5A
1
Auto Transformer
1φ
230/(0270V
1
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR LOAD TEST ON SINGLE PHASE TRANSFORMER (05A) MI
A P
A SPSTS
(010A) MI
300V, 5A UPF M
L
A
Fuse
Fuse C B
1Ø, 230V, 50Hz AC SUPPLY
V
150V P1
S1 (0150V) MI
(0300V) MI
V
33
P2
D P S T S
L O A D
S2
C NL N 230/(0270V) 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
EC2259
Electrical Engineering And Control System Lab Manual
Tabulation for Load test on single phase transformer Multiplication Factor =
S.No
Primary Voltage (VPy)
Volts
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 VNLVLOAD VLOAD
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.
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
(01A)
1
2
Ammeter
MI
(010A)
1
3
Voltmeter
MI
(0150V)
1
4
Voltmeter
MI
(0300V)
1
5 6
Watt meter
UPF
300V, 1A
1
Watt meter
UPF
75V, 5A
1
7
Auto Transformer
1φ
230/(0270V)
1
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR OPEN CIRCUIT TEST ON SINGLE PHASE TRANSFORMER
(05A) MI
A
P
A SPSTS
150V, 5A LPF
M
L
Fuse C
B
150V
P1
1Ø, 230V, 50Hz AC SUPPLY
V
S1
(0150V) MI
V P2
39
C
S2
NL
N 230/(0270V) 1Ø AUTO TRANSFORMER
1Ø 110/230V, 1KVA STEP UP TRANSFORMER
(0300V) MI
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR SHORT CIRCUIT TEST ON SINGLE PHASE TRANSFORMER
(05A) 300V, 10A UPF MI L A M
A
P SPSTS
A
Fuse C B
(010A) MI
75V P1 S1
1Ø, 230V, 50Hz AC SUPPLY
V
(075V) MI
SC
41
P2
S2
C
NL
N 230/(0270V) 1Ø AUTO TRANSFORMER
1Ø 230/110V, 1KVA STEP DOWN TRANSFORMER
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 secondary Voltage (V2O) Volts
Open Circuit power (WOC)
Obs.
Act.
Watts
Watts
Sh ort Circuit test Multiplication Factor =
S.No.
Short Circuit Primary Current (ISC) Amps
Short circuit Primary Voltage (VSC) Volts
Short Circuit secondary Current (I2S) Volts
Short Circuit power (WSC)
Obs.
Act.
Watts
Watts
Resultant Tabulation to find out the Efficiency Core (Or) Iron Loss = Rated Short Circuit Current (ISC) =
Fraction of Load (X)
1/4
1/2
3/4
1
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
%
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, XFraction of load KVA  power rating of Transformer and Cosφ  Power factor
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
EC2259
Electrical Engineering And Control System Lab Manual
Resultant Tabulation to find out the Regulation ISC =
Fraction of Load (X)
1
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.
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.
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
(010 A) (0600 V) (500V, 10A)
1 1 1


1
FORMULAE USED 1.Torque = (S1S2) (R+t/2) x 9.81 Nm 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 Nm.
3. Input Power = (W1+W2) Watts. W1, W2 – Wattmeter readings in Watts.
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR LOAD TEST ON THREE PHASE SQUIRRAL CAGE INDUCTION MOTOR STARDELTA STARTER 600V, 10A UPF M
R
L
L1
Fuse
V 415V, 50Hz, 3Ø AC SUPPLY Y
T P S T S
A1
600V
C
S1
(0600) V MI
R
A2 A2
A Fuse
L2 B1
(010) A MI
51 C
600V C1
B Fuse
M L 600V, 10A UPF
L3
C2
NL
S2
A1
B2
N
C2
N
C1 BRAKE DRUM
B1
B2 STATOR
EC2259
Electrical Engineering And Control System Lab Manual
4. Percentage of Efficiency = (Output Power/ Input Power) x 100%. 5. Percentage of Slip = (NSNr)/Ns x 100% NsSynchronous speed in rpm. NrRotor 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 abovementioned 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.
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
Load Voltage (VL)
Wattmeter readings
W1 Obs.
Volts
Input power
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
Nm
Watts
%
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 Nm
(B) Electrical characteristics:
Cos φ
N
IL
T
%
%
T in Nm 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.
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 
(010 A) (010 A) (0150 V) (0600 V) (050 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.
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR NO LOAD TEST ON THREE PHASE SQUIRREL CAGE INDUCTION MOTOR (Equivalent circuit) 415 / (0470) 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
(0600) V MI
R
A2
A2
B2
A
Fuse
B3
B
M L 600V, 10A LPF
Fuse C3 N
NL
B2 STATOR
C2
C
C1 B1
(010) A MI
A3
C2
600V
EC2259
Electrical Engineering And Control System Lab Manual
CIRCUIT DIAGRAM FOR BLOCKED ROTOR TEST ON THREE PHASE SQUIRREL CAGE INDUCTION MOTOR (Equivalent circuit) 415 / (0470) 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
(0150) V MI
R
A2
A2
B2
A
Fuse
C1 B1
B2
(010) A MI C2 STATOR A3
L M 150V, 10A UPF
Fuse C3
N
C
B3
B
NL
S2
150V
BRAKE DRUM
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 Actual Watts
Observed 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
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
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) = (NsNr) / 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 NoLoad 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.
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/s1)
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.
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.
NAME OF THE APPARATUS Ammeter Ammeter Ammeter Voltmeter Voltmeter Rheostat Rheostat Tachometer
TYPE
RANGE
QUANTITY
MC MC MI MI MC Wire Wound Wire Wound 
(02 A) (010 A) (010 A) (0600V) (050V) (500Ω, 1.2A) (300Ω, 1.7A) 
1 1 1 1 1 2 1 1
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
R
A
M
V (0600) V MI
N
B X
FF
Fuse
Y XX
AA
T P S T S
Fuse
(02) A
A 79
Fuse
220V DC SUPPLY
D P S T S
Fuse
Fuse
350 , 1.5A
Fuse
MC
(010) A MI
EC2259
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.
EC2259
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.
Field Current (If)
Open Circuit Line Voltage (V0L)
Open Circuit Phase Voltage (V0 (Ph))
Amps
Volts
Volts
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
EC2259
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
Lag. 90+
L Field Current (If ) in Amps
A
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.
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 splane encircles the point −1 + j 0 in the anti – clockwise direction as many times as the number of right half splane 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.
EC2259
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 cutoff 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. CUTOFF RATE The slope of the logmagnitude curve near the cut off frequency is called cutoff rate. The cutoff 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).
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 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.
EC2259
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.
EC2259
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. Settling Time t s
=
Settling Time t s
=
4
ξωn 3
ξωn
(For 2% error). (For 5% error).
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.
EC2259
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.
EC2259
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
P controller
PI controller
PID controller
EC2259
Electrical Engineering And Control System Lab Manual
Model Graph
RESULT Thus the design of P, PI and PID controller was done.
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
PROCEDURE
Where, T > 0 and a<1
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
PROCEDURE
Without Lag
With Lag
EC2259
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
Without Lead
With Lead
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.
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
(010A)
1
2
Ammeter
MC
(02A)
1
3
Ammeter
MI
(0300mA)
1
4
Voltmeter
MC
(0300V)
1
5
Voltmeter
MI
(0300V)
1
6
Rheostat
Wire wound
250 , 2A
1
7
Rheostat
Wire wound
350 , 1.5A
1
8
Single Phase Variac

230V/ (0270V)
1
EC2259
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.
EC2259
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.
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
(015A)
1
2
Ammeter
MC
(02A)
1
3
Ammeter
MI
(010A)
1
4
Voltmeter
MC
(0300V)
1
5
Voltmeter
MC
(050V)
1
6
Voltmeter
MI
(0300V)
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 / (0270V)
1
EC2259
Electrical Engineering And Control System Lab Manual
FORMULAE 1. Inertia Constant (J) ={{(Vav * Iav) / (Nav * N)}×(60/2 ) 2 ×((t1* t2) /(t1t2))} Kgm2 Where, Vav
(V1+V2) / 2
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 CoEfficient (f) =(2 /60) 2 ×(J / 2) ×(N12~N22) in Nm / rad /Sec Where, J
Inertia Constant in Kgm2 Angular displacement in rad / Sec = (2 Nav /60)
3. Back EMF Constant (Kb) =(VaIaRa) / (2 N/60) in Nm / Amps 4. Torque T = (S1~S2) × (R+ t/2) × 9.81 in Nm. 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)]}
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 Nm =Angular displacement of motor shaft in radian. J= Equivalent of moment of inertia of motor and load referred to motor shaft in kgm2 f=Equivalent viscous friction coefficient of motor and load referred to motor shaft in Nm / 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
d ( )/ dt
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)
=
KT E(s) (La S +Ra)

KTKb S (s) (La S +Ra)
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.
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.