The document is an electrical machines laboratory manual that provides instructions and procedures for various experiments involving DC machines. It includes circuit diagrams and procedures for open circuit and load tests on DC shunt generators and motors to obtain their characteristics curves. Procedures are also given for load tests on DC series motors and Swinburne's test to determine the efficiency of a DC machine working as both a motor and generator. The document lists the required equipment and provides formulas used in calculations along with sample tabulations and graphs.
This document contains the syllabus and procedures for experiments in the Electrical Machines I Lab. The experiments focus on obtaining characteristics of DC machines like generators and motors, as well as transformers. Key experiments include open/load characteristics of DC generators and motors, efficiency tests, and open/short circuit tests for transformers. Precautions are outlined and tabular columns provided to record readings and calculate performance parameters like efficiency.
This document contains the syllabus and procedures for experiments in the Electrical Machines I Lab. The experiments focus on obtaining characteristics of DC machines like generators and motors, as well as load tests to determine efficiency. Key experiments include open/load characteristics of DC generators and motors, Swinburne's test on DC shunt motors, and load tests to find efficiency of DC shunt and compound motors. Procedures provide connections, precautions and step-by-step methods for collecting data and analyzing results for each experiment.
This document contains instructions for conducting load tests on a self-excited DC shunt generator. It outlines the apparatus needed, including ammeters, voltmeters, rheostats, and a tachometer. The procedure describes adjusting the field rheostat to vary the field current and record open circuit voltage measurements. Load is then applied in steps using a rheostatic load, and armature current, voltage, and speed are measured to plot the generator's load characteristics curves. The goal is to determine the generator's performance under no load and varying load conditions.
The magnetization characteristic is different for increasing and decreasing values of field current (lf) due to hysteresis effect in the magnetic circuit of the generator. Hysteresis is the phenomenon due to which the magnetic domains in the iron core of the generator do not align instantaneously with the changing field current, resulting in a lag between the applied field current and the induced voltage. This causes the magnetization curve to form a loop instead of a single valued curve.
The document discusses electric motors and their operation. It describes how electric motors convert electrical energy into mechanical energy by using magnetic fields to generate torque that produces rotation. The speed of a motor can be controlled by adjusting the magnetic field strength or the voltage applied. When a motor operates, it simultaneously acts as a generator producing a counter EMF that limits the current flow. Starters are used to control motor starting by adding resistance that is gradually reduced as the motor speeds up to limit excessive starting currents.
The document provides information about DC motors and generators, including:
1) It describes the main construction parts of DC motors/generators including the armature, stator, poles, field windings, and commutator.
2) It explains the characteristics of shunt, series, and compound wound DC motors/generators including their circuit diagrams and load/speed-torque curves.
3) It discusses starting methods for DC motors including the use of a starter resistance to limit starting current.
The document describes experiments to be performed in a control systems lab. It includes 10 experiments related to studying different components of control systems like AC and DC servo motors, magnetic amplifiers, lead-lag compensators, PID controllers, and MATLAB simulations. For each experiment, it provides the aim, apparatus required, theory, procedure, observations table and discussion. The experiments aim to analyze characteristics and behavior of components, plot graphs, and understand control system design principles.
The document is an electrical machines laboratory manual that provides instructions and procedures for various experiments involving DC machines. It includes circuit diagrams and procedures for open circuit and load tests on DC shunt generators and motors to obtain their characteristics curves. Procedures are also given for load tests on DC series motors and Swinburne's test to determine the efficiency of a DC machine working as both a motor and generator. The document lists the required equipment and provides formulas used in calculations along with sample tabulations and graphs.
This document contains the syllabus and procedures for experiments in the Electrical Machines I Lab. The experiments focus on obtaining characteristics of DC machines like generators and motors, as well as transformers. Key experiments include open/load characteristics of DC generators and motors, efficiency tests, and open/short circuit tests for transformers. Precautions are outlined and tabular columns provided to record readings and calculate performance parameters like efficiency.
This document contains the syllabus and procedures for experiments in the Electrical Machines I Lab. The experiments focus on obtaining characteristics of DC machines like generators and motors, as well as load tests to determine efficiency. Key experiments include open/load characteristics of DC generators and motors, Swinburne's test on DC shunt motors, and load tests to find efficiency of DC shunt and compound motors. Procedures provide connections, precautions and step-by-step methods for collecting data and analyzing results for each experiment.
This document contains instructions for conducting load tests on a self-excited DC shunt generator. It outlines the apparatus needed, including ammeters, voltmeters, rheostats, and a tachometer. The procedure describes adjusting the field rheostat to vary the field current and record open circuit voltage measurements. Load is then applied in steps using a rheostatic load, and armature current, voltage, and speed are measured to plot the generator's load characteristics curves. The goal is to determine the generator's performance under no load and varying load conditions.
The magnetization characteristic is different for increasing and decreasing values of field current (lf) due to hysteresis effect in the magnetic circuit of the generator. Hysteresis is the phenomenon due to which the magnetic domains in the iron core of the generator do not align instantaneously with the changing field current, resulting in a lag between the applied field current and the induced voltage. This causes the magnetization curve to form a loop instead of a single valued curve.
The document discusses electric motors and their operation. It describes how electric motors convert electrical energy into mechanical energy by using magnetic fields to generate torque that produces rotation. The speed of a motor can be controlled by adjusting the magnetic field strength or the voltage applied. When a motor operates, it simultaneously acts as a generator producing a counter EMF that limits the current flow. Starters are used to control motor starting by adding resistance that is gradually reduced as the motor speeds up to limit excessive starting currents.
The document provides information about DC motors and generators, including:
1) It describes the main construction parts of DC motors/generators including the armature, stator, poles, field windings, and commutator.
2) It explains the characteristics of shunt, series, and compound wound DC motors/generators including their circuit diagrams and load/speed-torque curves.
3) It discusses starting methods for DC motors including the use of a starter resistance to limit starting current.
The document describes experiments to be performed in a control systems lab. It includes 10 experiments related to studying different components of control systems like AC and DC servo motors, magnetic amplifiers, lead-lag compensators, PID controllers, and MATLAB simulations. For each experiment, it provides the aim, apparatus required, theory, procedure, observations table and discussion. The experiments aim to analyze characteristics and behavior of components, plot graphs, and understand control system design principles.
This document describes a field test conducted on a DC series motor to determine its efficiency. The test involves coupling two similar 3 kW, 220 V DC series motors together, with one operating as a motor driving the other as a generator. Voltage, current and speed measurements are taken under load. Calculations are shown to find losses, efficiency of the motor (73.43%) and generator (71.77%). A MATLAB program is provided that replicates the manual calculations. The results verify the efficiency values determined from the field test.
The document describes experiments on electric drive systems in the Electrical Department lab at JIS College of Engineering. The 10 listed experiments include:
1. Studying thyristor controlled DC drives and chopper fed DC drives.
2. Studying AC single phase motor speed control using a TRIAC.
3. Studying PWM inverter fed 3-phase induction motor control using software.
The document provides theory, circuit diagrams, and procedures for each experiment. It describes using equipment like thyristors, choppers, inverters, motors, and software to control motor speed and study electric drive systems.
This document describes an experiment to obtain the magnetization characteristics of a separately excited DC generator. The aim is to find the critical field resistance. The nameplate details and components used like the voltmeter, ammeter, and rheostats are provided. The procedure involves connecting the circuit and bringing the motor-generator set up to rated speed. Readings of generated voltage and field current are then taken at open switch position and as the field resistance is decreased. A table to record readings and a graph are included to present the magnetization characteristics and calculate the critical field resistance.
This document provides an overview of DC motors, including their basic working principles, types (shunt, series, compound), characteristics such as torque-current and speed-current relationships, and components like armature and field windings. It describes how DC motors function by converting electrical energy from a power source into mechanical rotation of an armature, and how speed can be controlled through varying the current. Losses within the motor such as copper and iron losses are also discussed.
This document provides information about different types of DC motor starters and AC motor starters. It discusses two point, three point, and four point starters for DC motors. It explains how each type protects the motor from high starting currents and overloads. It also covers various AC motor starting methods like auto transformer starting, star-delta starting, and direct online starting. Star-delta and auto transformer starting reduce the starting current by initially applying a lower voltage to the motor. Direct online starting applies full voltage but is only suitable for small motors due to the large starting currents involved.
This document provides information about conducting experiments to study different types of induction motor starters, including direct online (DOL), auto transformer, star-delta, and rotor resistance starters. It describes the theory behind using starters, the necessity of starters to reduce starting current and protect the motor, and gives details about the operation and advantages of each type of starter. The objectives are to study and connect examples of each starter type and understand their working principles. Precautions and procedures for conducting the experiments are also outlined.
This document provides information about experiments conducted in an electrical machines lab at Mehran University of Engineering and Technology. It includes an index listing 12 experiments conducted between August and October on topics like DC generators, motors, and control systems. Practical 1 provides an introduction to electrical machine equipment like DC motors, generators, transformers, and control panels. It describes the components and operating principles. The document also includes circuit diagrams, readings tables and conclusions from experiments verifying open circuit characteristics of separately excited DC generators and self-excited series DC generators.
This document provides instructions for students taking an Electrical and Electronics Engineering laboratory course on Power Electronics and Drives. It begins with general safety instructions for all EEE lab courses, such as being punctual and wearing proper attire. Next, it lists 13 experiments to be performed in the course, covering topics like gate pulse generation, characteristics of power electronic devices, and converter circuits. Finally, it provides details on the experiments, including circuit diagrams, procedures, expected waveforms, and requirements for recording observations and results. The document aims to prepare students for experiments examining key concepts in power electronics and motor drives.
This document contains instructions for performing experiments on electrical machines in a lab. It provides safety guidelines and procedures for two experiments: 1) Speed control of a DC shunt motor using armature and field control methods. Graphs of speed vs armature voltage and speed vs field current are to be plotted. 2) Open circuit and short circuit tests on a single-phase transformer to determine its equivalent circuit parameters and efficiency. Calculations are to be shown to find the transformer's resistance, reactance, regulation, and efficiency at different loads. Precautions for working in the machine lab and sample viva questions are also included.
This document describes the design and performance study of a two-quadrant chopper drive. It begins with an introduction to choppers and their classification. It then discusses the different types of choppers - first quadrant, second quadrant, two-quadrant types A and B. It outlines the operations carried out by choppers and the components used in the model. Observations from the test circuit are presented along with graphs. Advantages include the ability for forward motoring and braking. Applications include electric vehicles and traction motor control. The conclusion is that regenerative braking is possible using a two-quadrant chopper.
IRJET- Design and Implementation of Isolated Multi-Output Flyback ConverterIRJET Journal
This document describes the design and implementation of an isolated multi-output flyback converter. A flyback converter uses a single switch and transformer to provide isolated output voltages from an input source. The designed converter uses a toroidal transformer with multiple secondary windings to generate multiple isolated output voltages at fixed levels. Simulation results and specifications for the transformer, switch, and outputs are provided. The flyback converter provides an efficient and low-cost solution for applications requiring multiple isolated low-power DC outputs.
This document describes a project to control the speed of a single-phase induction motor using a TRIAC. It includes sections on the circuit description, induction motor working, SCR, TRIAC, DIAC, applications, advantages and disadvantages. The circuit uses a DIAC to trigger a TRIAC, allowing control of the firing angle to vary the voltage applied to the motor. This provides speed control of the induction motor for applications like pumps, fans and refrigeration.
This document provides information about a power electronics laboratory manual for a fifth semester electrical engineering course. It includes a list of 10 experiments on topics like the characteristics of SCRs, TRIACs, MOSFETs, and IGBTs. It also covers experiments on AC to DC converters, choppers, and PWM inverters. The document provides circuit diagrams, procedures, and sample questions for each experiment. It is intended to guide students in learning about and conducting various experiments related to power electronics components and applications.
The document provides information on performing no load and blocked rotor tests on induction motors to determine their equivalent circuit parameters.
1. No load and blocked rotor tests involve measuring voltage, current, power factor and resistance/reactance values at no load and locked rotor conditions.
2. The tests allow determining parameters like stator and rotor resistances and reactances which are used to develop an equivalent circuit model of the motor.
3. The equivalent circuit model enables analyzing the motor's performance characteristics like torque, efficiency and power factor under different operating conditions.
1. The document describes experiments to study the characteristics of various power electronics devices like SCR, TRIAC, MOSFET, IGBT using different circuit connections and varying parameters.
2. Procedures to study half wave and full wave rectification using RC triggering circuit are provided along with the relevant circuit diagram and waveforms. Readings are noted in a tabular column and graphs are plotted.
3. Signatures of staff conducting the experiments are included indicating the experiments were performed in the power electronics lab.
The BA6209 and BA6209N ICs are motor driver chips that can operate motors in forward, reverse, or braking modes. They can handle motor currents up to 1.6A and have features such as integrated braking, rush current absorption, and motor speed control via an input pin. The chips are designed to drive brush motors typically used in devices like VCRs and cassette recorders.
This document provides the procedure to study the performance and waveforms of half wave rectifier (HWR) and full wave rectifier (FWR) using an RC triggering circuit. The experiment involves making connections of the circuit and noting voltage and current readings at different resistor (R) values. Graphs of output voltage, current and power vs firing/conduction angle are plotted. The practical output is compared with the theoretical output voltage calculation.
The document provides instructions for experiments on power electronics laboratory equipment. It includes circuits and procedures to study the characteristics of SCR, MOSFET, IGBT using different firing circuits like R, RC and UJT. The objectives are to draw the output and transfer characteristics of these devices, determine threshold voltages and understand the operation of different firing circuits. Graphs are plotted from the observations and results are analyzed to understand the concepts of latching current, pinch-off voltage and voltage/current control of the devices.
DC machines operate on the principles of electromagnetic induction and force. They have commutators, field windings, and armature windings. DC machines can operate as motors or generators depending on the direction of power flow. Speed in DC motors can be controlled through methods like armature voltage control, field control, and armature resistance control. DC generators have open-circuit, load, and external characteristics that define their performance based on variables like terminal voltage, field current, and load current. Efficiency is impacted by losses such as copper losses and mechanical losses.
This document describes a field test conducted on a DC series motor to determine its efficiency. The test involves coupling two similar 3 kW, 220 V DC series motors together, with one operating as a motor driving the other as a generator. Voltage, current and speed measurements are taken under load. Calculations are shown to find losses, efficiency of the motor (73.43%) and generator (71.77%). A MATLAB program is provided that replicates the manual calculations. The results verify the efficiency values determined from the field test.
The document describes experiments on electric drive systems in the Electrical Department lab at JIS College of Engineering. The 10 listed experiments include:
1. Studying thyristor controlled DC drives and chopper fed DC drives.
2. Studying AC single phase motor speed control using a TRIAC.
3. Studying PWM inverter fed 3-phase induction motor control using software.
The document provides theory, circuit diagrams, and procedures for each experiment. It describes using equipment like thyristors, choppers, inverters, motors, and software to control motor speed and study electric drive systems.
This document describes an experiment to obtain the magnetization characteristics of a separately excited DC generator. The aim is to find the critical field resistance. The nameplate details and components used like the voltmeter, ammeter, and rheostats are provided. The procedure involves connecting the circuit and bringing the motor-generator set up to rated speed. Readings of generated voltage and field current are then taken at open switch position and as the field resistance is decreased. A table to record readings and a graph are included to present the magnetization characteristics and calculate the critical field resistance.
This document provides an overview of DC motors, including their basic working principles, types (shunt, series, compound), characteristics such as torque-current and speed-current relationships, and components like armature and field windings. It describes how DC motors function by converting electrical energy from a power source into mechanical rotation of an armature, and how speed can be controlled through varying the current. Losses within the motor such as copper and iron losses are also discussed.
This document provides information about different types of DC motor starters and AC motor starters. It discusses two point, three point, and four point starters for DC motors. It explains how each type protects the motor from high starting currents and overloads. It also covers various AC motor starting methods like auto transformer starting, star-delta starting, and direct online starting. Star-delta and auto transformer starting reduce the starting current by initially applying a lower voltage to the motor. Direct online starting applies full voltage but is only suitable for small motors due to the large starting currents involved.
This document provides information about conducting experiments to study different types of induction motor starters, including direct online (DOL), auto transformer, star-delta, and rotor resistance starters. It describes the theory behind using starters, the necessity of starters to reduce starting current and protect the motor, and gives details about the operation and advantages of each type of starter. The objectives are to study and connect examples of each starter type and understand their working principles. Precautions and procedures for conducting the experiments are also outlined.
This document provides information about experiments conducted in an electrical machines lab at Mehran University of Engineering and Technology. It includes an index listing 12 experiments conducted between August and October on topics like DC generators, motors, and control systems. Practical 1 provides an introduction to electrical machine equipment like DC motors, generators, transformers, and control panels. It describes the components and operating principles. The document also includes circuit diagrams, readings tables and conclusions from experiments verifying open circuit characteristics of separately excited DC generators and self-excited series DC generators.
This document provides instructions for students taking an Electrical and Electronics Engineering laboratory course on Power Electronics and Drives. It begins with general safety instructions for all EEE lab courses, such as being punctual and wearing proper attire. Next, it lists 13 experiments to be performed in the course, covering topics like gate pulse generation, characteristics of power electronic devices, and converter circuits. Finally, it provides details on the experiments, including circuit diagrams, procedures, expected waveforms, and requirements for recording observations and results. The document aims to prepare students for experiments examining key concepts in power electronics and motor drives.
This document contains instructions for performing experiments on electrical machines in a lab. It provides safety guidelines and procedures for two experiments: 1) Speed control of a DC shunt motor using armature and field control methods. Graphs of speed vs armature voltage and speed vs field current are to be plotted. 2) Open circuit and short circuit tests on a single-phase transformer to determine its equivalent circuit parameters and efficiency. Calculations are to be shown to find the transformer's resistance, reactance, regulation, and efficiency at different loads. Precautions for working in the machine lab and sample viva questions are also included.
This document describes the design and performance study of a two-quadrant chopper drive. It begins with an introduction to choppers and their classification. It then discusses the different types of choppers - first quadrant, second quadrant, two-quadrant types A and B. It outlines the operations carried out by choppers and the components used in the model. Observations from the test circuit are presented along with graphs. Advantages include the ability for forward motoring and braking. Applications include electric vehicles and traction motor control. The conclusion is that regenerative braking is possible using a two-quadrant chopper.
IRJET- Design and Implementation of Isolated Multi-Output Flyback ConverterIRJET Journal
This document describes the design and implementation of an isolated multi-output flyback converter. A flyback converter uses a single switch and transformer to provide isolated output voltages from an input source. The designed converter uses a toroidal transformer with multiple secondary windings to generate multiple isolated output voltages at fixed levels. Simulation results and specifications for the transformer, switch, and outputs are provided. The flyback converter provides an efficient and low-cost solution for applications requiring multiple isolated low-power DC outputs.
This document describes a project to control the speed of a single-phase induction motor using a TRIAC. It includes sections on the circuit description, induction motor working, SCR, TRIAC, DIAC, applications, advantages and disadvantages. The circuit uses a DIAC to trigger a TRIAC, allowing control of the firing angle to vary the voltage applied to the motor. This provides speed control of the induction motor for applications like pumps, fans and refrigeration.
This document provides information about a power electronics laboratory manual for a fifth semester electrical engineering course. It includes a list of 10 experiments on topics like the characteristics of SCRs, TRIACs, MOSFETs, and IGBTs. It also covers experiments on AC to DC converters, choppers, and PWM inverters. The document provides circuit diagrams, procedures, and sample questions for each experiment. It is intended to guide students in learning about and conducting various experiments related to power electronics components and applications.
The document provides information on performing no load and blocked rotor tests on induction motors to determine their equivalent circuit parameters.
1. No load and blocked rotor tests involve measuring voltage, current, power factor and resistance/reactance values at no load and locked rotor conditions.
2. The tests allow determining parameters like stator and rotor resistances and reactances which are used to develop an equivalent circuit model of the motor.
3. The equivalent circuit model enables analyzing the motor's performance characteristics like torque, efficiency and power factor under different operating conditions.
1. The document describes experiments to study the characteristics of various power electronics devices like SCR, TRIAC, MOSFET, IGBT using different circuit connections and varying parameters.
2. Procedures to study half wave and full wave rectification using RC triggering circuit are provided along with the relevant circuit diagram and waveforms. Readings are noted in a tabular column and graphs are plotted.
3. Signatures of staff conducting the experiments are included indicating the experiments were performed in the power electronics lab.
The BA6209 and BA6209N ICs are motor driver chips that can operate motors in forward, reverse, or braking modes. They can handle motor currents up to 1.6A and have features such as integrated braking, rush current absorption, and motor speed control via an input pin. The chips are designed to drive brush motors typically used in devices like VCRs and cassette recorders.
This document provides the procedure to study the performance and waveforms of half wave rectifier (HWR) and full wave rectifier (FWR) using an RC triggering circuit. The experiment involves making connections of the circuit and noting voltage and current readings at different resistor (R) values. Graphs of output voltage, current and power vs firing/conduction angle are plotted. The practical output is compared with the theoretical output voltage calculation.
The document provides instructions for experiments on power electronics laboratory equipment. It includes circuits and procedures to study the characteristics of SCR, MOSFET, IGBT using different firing circuits like R, RC and UJT. The objectives are to draw the output and transfer characteristics of these devices, determine threshold voltages and understand the operation of different firing circuits. Graphs are plotted from the observations and results are analyzed to understand the concepts of latching current, pinch-off voltage and voltage/current control of the devices.
DC machines operate on the principles of electromagnetic induction and force. They have commutators, field windings, and armature windings. DC machines can operate as motors or generators depending on the direction of power flow. Speed in DC motors can be controlled through methods like armature voltage control, field control, and armature resistance control. DC generators have open-circuit, load, and external characteristics that define their performance based on variables like terminal voltage, field current, and load current. Efficiency is impacted by losses such as copper losses and mechanical losses.
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1. 20EE012 – EEE- SRIT
LIST OF EXPERIMENTS
20EE012 - ELECTRICAL MACHINES LABORATORY – I
1. Open circuit and load characteristics of self excited DC shunt generators.
2. Load characteristics of DC compound generator with differential and cumulative
connection.
3. Load characteristics of DC shunt and compound motor.
4. Load characteristics of DC series motor.
5. Swinburne’s test and speed control of DC shunt motor.
6. Hopkinson’s test on DC motor – generator set.
7. Load test on single-phase transformer and three phase transformer
connections.
8. Open circuit and short circuit tests on single phase transformer.
9. Sumpner’s test on transformers.
10. Separation of no-load losses in single phase transformer.
11. Study of Starters
2. 20EE012 – EEE- SRIT
INDEX
S.No Date Experiment Name Marks Sign
1A Open circuit characteristics of Self excited DC shunt
generators.
1B Load characteristics of Self excited DC shunt
generators.
2 Load characteristics of DC compound generator –
Differential & Cumulative
3A Load characteristics of DC shunt motor
3B Load characteristics of DC compound motor
4 Load characteristics of DC series motor
5A Swinburne’s test
5B Speed control of DC shunt motor
6 Hopkinson’s test
7 Load test on single-phase transformer
8 Open circuit and short circuit tests on single phase
transformer
9 Sumpner’s test on transformers
10 Separation of no-load losses in single phase
transformer
LAB INCHARGE
4. 20EE012 – EEE- SRIT
OPEN CIRCUIT CHARACTERISTICS OF SELF EXCITED
DC SHUNT GENERATOR
Ex.No:1A
Date:
AIM:
To obtain open circuit characteristics of self excited DC shunt generator and to
find its critical resistance.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter (0-1)A MC 1
2 Voltmeter (0-300)V MC 1
3 Rheostats 1250, 0.8A Wire Wound 2
4 SPST Switch - - 1
5 Tachometer (0-1500)rpm Digital 1
6 Connecting Wires 2.5sq.mm. Copper Few
PRECAUTIONS:
1. The field rheostat of motor should be in minimum resistance position at the time
of starting and stopping the machine.
2. The field rheostat of generator should be in maximum resistance position at the
time of starting and stopping the machine.
3. SPST switch is kept open during starting and stopping.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking minimum position of motor field rheostat, maximum position of
generator field rheostat, DPST switch is closed and starting resistance is
gradually removed.
5. 20EE012 – EEE- SRIT
TABULAR COLOUMN:
S.No.
Field Current
If (Amps)
Armature Voltage
Eo (Volts)
1.
2.
3.
4.
5.
6.
MODEL GRAPH:
Critical Resistance = Eo / If Ohms
If
Eo
If (Amps)
E
o
(Volts)
6. 20EE012 – EEE- SRIT
3. By adjusting the field rheostat, the motor is brought to rated speed.
4. Voltmeter and ammeter readings are taken when the SPST switch is kept open.
5. After closing the SPST switch, by varying the generator field rheostat, voltmeter
and ammeter readings are taken.
6. After bringing the generator rheostat to maximum position, field rheostat of motor
to minimum position, SPST switch is opened and DPST switch is opened.
RESULT:
Thus open circuit characteristics of self excited DC shunt generator are obtained
and its critical resistance is determined.
8. 20EE012 – EEE- SRIT
Ex.No.1B
Date:
LOAD CHARACTERISTICS OF SELF EXCITED
DC SHUNT GENERATOR
AIM:
To obtain internal and external characteristics of DC shunt generator.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter
(0-2)A
(0-20) A
MC
MC
1
1
2 Voltmeter (0-300)V MC 1
3 Rheostats 1200, 0.8A Wire Wound 2
4 Loading Rheostat 5KW, 230V - 1
5 Tachometer (0-1500)rpm Digital 1
6 Connecting Wires 2.5sq.mm. Copper Few
FORMULAE:
Eg = V + Ia Ra (Volts)
Ia = IL + If (Amps)
Eg :Generated emf in Volts V :Terminal Voltage in Volts
Ia :Armature Current in Amps IL :Line Current in Amps
If :Field Current in Amps Ra :Armature Resistance in Ohms
PRECAUTIONS:
1. The field rheostat of motor should be at minimum position.
2. The field rheostat of generator should be at maximum position.
3. No load should be connected to generator at the time of starting and stopping.
9. 20EE012 – EEE- SRIT
TABULAR COLUMN:
S.No.
Field
Current
If (Amps)
Load
Current
IL (Amps)
Terminal
Voltage
(V) Volts
Ia = IL + If
(Amps)
Eg =V + Ia Ra
(Volts)
1.
2.
3.
4.
5.
6.
MODEL GRAPH:
E Vs IL
(Int Char)
V Vs IL
(Ext Char)
If, IL (Amps)
V
L
,
E
(Volts)
10. 20EE012 – EEE- SRIT
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking minimum position of DC shunt motor field rheostat and maximum
position of DC shunt generator field rheostat, DPST switch is closed and starting
resistance is gradually removed.
3. Under no load condition, Ammeter and Voltmeter readings are noted, after
bringing the voltage to rated voltage by adjusting the field rheostat of generator.
4. Load is varied gradually and for each load, voltmeter and ammeter readings are
noted.
5. Then the generator is unloaded and the field rheostat of DC shunt generator is
brought to maximum position and the field rheostat of DC shunt motor to
minimum position, DPST switch is opened.
RESULT:
Thus the load characteristics of self excited DC shunt generator is obtained.
11. 20EE012 – EEE- SRIT
Viva Questions :
1. What is the principle of DC generator?
2. Mention the application of self excited DC generator.
3. Give the advantages and disadvantages of self excited DC generators.
4. What will be the value of current in open circuit condition?
5. What is the purpose of starter?
6. On what occasions DC generators may not have residual flux?
7. Define the term critical resistance referred to DC shunt generator.
8. Define the term critical speed in DC shunt generator.
9. The efficiency of generator rises to a maximum value and then decreases. Why?
10. What do you mean by residual magnetism in DC shunt generators?
13. 20EE012 – EEE- SRIT
LOAD CHARACTERISTICS OF DC COMPOUND GENERATOR
Ex.No.2
Date:
AIM:
To obtain the load characteristics of DC Compound generator under cumulative
and differential mode condition.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter
(0-2)A
(0-20) A
MC
MC
1
1
2 Voltmeter (0-300)V MC 1
3 Rheostats 1200, 0.8A Wire Wound 2
4 Loading Rheostat 5KW, 230V - 1
5 Tachometer (0-1500)rpm Digital 1
6 Connecting Wires 2.5sq.mm. Copper Few
PRECAUTIONS:
1. The field rheostat of motor should be at minimum position.
2. The field rheostat of generator should be at maximum position.
3. No load should be connected to generator at the time of starting and
stopping.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking minimum position of DC shunt motor field rheostat and
maximum position of DC shunt generator field rheostat, DPST switch is
closed and starting resistance is gradually removed.
3. Under no load condition, Ammeter and Voltmeter readings are noted, after
bringing the voltage to rated voltage by adjusting the field rheostat of
generator.
14. 20EE012 – EEE- SRIT
TABULAR COLUMN:
S.No.
Cumulatively Compounded Differentially Compounded
V (Volts) IL (Amps) V (Volts) IL (Amps)
1.
2.
3.
4.
5.
6.
MODEL GRAPH:
Cumulatively Compounded
Differentially Compounded
IL (Amps)
V
(Volts)
15. 20EE012 – EEE- SRIT
4. Load is varied gradually and for each load, voltmeter and ammeter readings
are noted.
5. Then the generator is unloaded and the field rheostat of DC shunt generator
is brought to maximum position and the field rheostat of DC shunt motor to
minimum position, DPST switch is opened.
6. The connections of series field windings are reversed the above steps are
repeated.
7. The values of voltage for the particular currents are compared and then the
differential and cumulative compounded DC generator is concluded
accordingly.
RESULT:
Thus load characteristics of DC compound generator under cumulative and
differential mode condition are obtained
16. 20EE012 – EEE- SRIT
Viva Questions :
1. What is the standard direction of rotation of the DC generator and DC
motor?
2. How should a generator be started?
3. What are the indications and causes of an overloaded generator?
4. Generator operates in the principle of Fleming’s .
5. Whether compound generators can be used as shunt and series generators?
How?
6. An electrical machine can be loaded up to -------------------- % of rated current.
7. Why series generators are not used for power generation at the power house?
8. How do we conclude that connections between field coils and armature are
correct?
9. How will you differentiate cumulative compound and differential compound
generators?
10.Define commutation.
18. 20EE012 – EEE- SRIT
Ex.No.3A
Date:
LOAD TEST ON DC SHUNT MOTOR
AIM:
To conduct load test on DC shunt motor and to find efficiency.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter (0-20)A MC 1
2 Voltmeter (0-300)V MC 1
3 Rheostat 1250, 0.8A Wire Wound 1
4 Tachometer (0-1500) rpm Digital 1
5 Connecting Wires 2.5sq.mm. Copper Few
FORMULAE:
Circumference
R =------------------------ m
100 x2
Torque T = (S1 S2) x R x 9.81 Nm
Input Power Pi = VI Watts
2NT
Output Power Pm = ---------- Watts
60
Output Power
Efficiency % = -------------------- x 100%
Input Power
19. 20EE012 – EEE- SRIT
TABULAR COLUMN:
S.No.
Voltage
V
(Volts)
Current
I
(Amps)
Spring
Balance
Reading (S1
S2)Kg
Speed
N
(rpm)
Torque
T
(Nm)
Output
Power
Pm
(Watts)
Input
Power
Pi
(Watts)
Efficie
ncy
%
S1
(Kg)
S2
(Kg)
1.
2.
3.
4.
5.
6.
MODEL GRAPHS:
y
x
y3 y2
N
T
Output Power
Efficiency
%
Torque
T
(Nm)
Speed
N
(rpm)
Speed
N
21. 20EE012 – EEE- SRIT
PRECAUTIONS:
1. DC shunt motor should be started and stopped under no load condition.
2. Field rheostat should be kept in the minimum position.
3. Brake drum should be cooled with water when it is under load.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the no load condition, and minimum field rheostat position, DPST
switch is closed and starter resistance is gradually removed.
3. The motor is brought to its rated speed by adjusting the field rheostat.
4. Ammeter, Voltmeter readings, speed and spring balance readings are noted
under no load condition.
5. The load is then added to the motor gradually and for each load, voltmeter,
ammeter, spring balance readings and speed of the motor are noted.
6. The motor is then brought to no load condition and field rheostat to minimum
position, then DPST switch is opened.
RESULT:
Thus load test on DC shunt motor is conducted and its efficiency is determined.
23. 20EE012 – EEE- SRIT
Ex.No.3B
Date:
LOAD TEST ON DC COMPOUND MOTOR
AIM:
To conduct load test on DC compound motor and to find its efficiency.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter (0-20)A MC 1
2 Voltmeter (0-300)V MC 1
3 Rheostat 1250, 0.8A Wire Wound 1
4 Tachometer (0-1500) rpm Digital 1
5 Connecting Wires 2.5sq.mm. Copper Few
FORMULAE:
Circumference
R =------------------------ m
100 x2
Torque T = (S1 S2) x R x 9.81 Nm
Input Power Pi = VI Watts
2NT
Output Power Pm = ---------- Watts
60
Output Power
Efficiency % = -------------------- x 100%
Input Power
24. 20EE012 – EEE- SRIT
TABULAR COLOUMN:
S.No
Voltage
V
(Volts)
Current
I
(Amps)
Spring
Balance
Reading
(S1 S2)
Kg
Speed
N
(rpm)
Torque
T
(Nm)
Output
Power
Pm
(Watts)
Input
Power
Pi
(Watts)
Efficie
ncy
%
S1
(Kg)
S2
(Kg)
1.
2.
3.
4.
5.
6.
MODEL GRAPHS:
y
x
Torque T (Nm)
y3 y2 y1
N
T
Output Power (Watts)
Efficiency
%
Torque
T
(Nm)
Speed
N
(rpm)
Speed
N
(rpm)
25. 20EE012 – EEE- SRIT
PRECAUTIONS:
1. DC compound motor should be started and stopped under no load condition.
2. Field rheostat should be kept in the minimum position.
3. Brake drum should be cooled with water when it is under load.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the no load condition, and minimum field rheostat position,
DPST switch is closed and starter resistance is gradually removed.
3. The motor is brought to its rated speed by adjusting the field rheostat.
4. Ammeter, Voltmeter readings, speed and spring balance readings are noted
under no load condition.
5. The load is then added to the motor gradually and for each load, voltmeter,
ammeter, spring balance readings and speed of the motor are noted.
6. The motor is then brought to no load condition and field rheostat to minimum
position, then DPST switch is opened.
RESULT:
Thus load test on DC compound motor is conducted and its efficiency is
determined.
26. 20EE012 – EEE- SRIT
Viva Questions
1. State the principle of DC motor.
2. How may the direction of DC motor be able to be reversed?
3. Why the field rheostat of DC motor is kept at minimum position while starting?
4. What will happen if the field of the DC motor is opened?
5. What will happen if both the field current and armature current are reversed?
6. What will happen if the shunt motor is directly connected across the supply line?
7. Mention the applications of DC compound motor.
8. The differentially compounded motor has a tendency to start in the opposite
direction, why?
9. What are the advantages of a compound motor?
10.Differentiate between cumulative compound and differential compound motors.
28. 20EE012 – EEE- SRIT
LOAD TEST ON DC SERIES MOTOR
Ex.No.4
Date:
AIM:
To conduct load test on DC Series Motor and to find efficiency.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter (0-20)A MC 1
2 Voltmeter (0-300)V MC 1
3 Tachometer
(0-3000)
rpm
Digital 1
4 Connecting Wires 2.5sq.mm. Copper Few
FORMULAE:
Circumference
R =------------------------ m
100 x2
Torque T = (S1 S2) x R x 9.81 Nm
Input Power Pi = VI Watts
2NT
Output Power Pm = ---------- Watts
60
Output Power
Efficiency % = -------------------- x 100%
Input Power
29. 20EE012 – EEE- SRIT
TABULAR COLOUMN:
S.No
Voltage
V
(Volts)
Current
I
(Amps)
Spring
Balance
Reading
(S1 S2)
Kg
Speed
N
(rpm)
Torque
T
(Nm)
Output
Power
Pm
(Watts)
Input
Power
Pi
(Watts)
Efficie
ncy
%
S1
(Kg)
S2
(Kg)
1.
2.
3.
4.
5.
6.
MODEL GRAPH:
y3 y2 y1
T
E
N
Output Power (Watts)
Efficiency
%
Torque
T
(Nm)
Speed
N
(rpm)
30. 20EE012 – EEE- SRIT
PRECAUTIONS:
1. The motor should be started and stopped with load
2. Brake drum should be cooled with water when it is under load.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the load condition, DPST switch is closed and starter resistance is
gradually removed.
3. For various loads, Voltmeter, Ammeter readings, speed and spring balance
readings are noted.
4. After bringing the load to initial position, DPST switch is opened.
RESULT:
Thus load test on DC series motor is conducted and its efficiency is determined.
31. 20EE012 – EEE- SRIT
Viva Questions:
1. What are the applications of DC series motors?
2. What are the special features of a DC series motors?
3. Which type of starter is used for DC series motors?
4. How will you control the speed of DC series motor?
5. What will happen to the speed of series motor when the supply voltage is
reduced?
6. What is the importance of no-load current of the motor?
7. Why we use starters to start DC motors?
8. DC series motors should never be started on no-load. Why?
9. Why the DC series motors have high starting torque?
10.What is meant by speed losses in DC machines?
33. 20EE012 – EEE- SRIT
ao
a
SWINBURNE’S TEST
Ex. No. 5A
Date:
AIM:
To conduct Swinburne’s test on DC machine to Pre-determine the efficiency
when working as generator and motor without actually loading the machine.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter (0-20) A MC 1
2 Voltmeter (0-300) V MC 1
3 Rheostats 1250, 0.8A
Wire
Wound
1
4 Tachometer (0-3000) rpm Digital 1
5 Resistive Load 5KW,230V - 1
6 Connecting Wires 2.5sq.mm. Copper Few
FORMULAE:
Hot Resistance Ra = 1.2 X R Ω
Constant losses = VIo – I 2
Ra watts
Where Iao = (Io – If) Amps
AS MOTOR:
Load Current IL = Amps
Armature current Ia = IL – If Amps
Copper loss = I 2
Ra watts
Total losses = Copper loss + Constant losses
Input Power = VIL watts
34. 20EE012 – EEE- SRIT
TABULAR COLOUMN:
AS MOTOR: If = A
S. No.
V
(Volts)
IL
(Amps)
Ia
(Amps)
Ia2
Ra
(Watts)
Total
Losses
W
(Watts)
Output
Power
(Watts)
Input
Power
(Watts)
Efficiency
%
1.
2.
3.
4.
5.
6.
AS GENERATOR:
If = A
S. No.
V
(Volts)
I1
(Amps)
Ia
(Amps)
Ia2
Ra
(Watts)
Total
Losses
(Watts)
Output
Power
(Watts)
Input
Power
(Watts)
Efficiency
%
1.
2.
3.
4.
5.
6.
35. 20EE012 – EEE- SRIT
a
Output Power = Input Power – Total losses
Output power
Efficiency % = ---------------------------X 100%
Input Power
AS GENERATOR:
Load Current IL = Amps
Armature current Ia = IL + If Amps
Copper loss = I 2
Ra watts
Total losses = Copper loss + Constant losses
Output Power = VIL watts
Input Power = Output Power +Total losses
Output power
Efficiency % = ------------------------X 100%
Input Power
PRECAUTIONS:
The field rheostat should be in the minimum position at the time of starting and
stopping the motor
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the minimum position of field rheostat, DPST switch is closed and
starting resistance is gradually removed.
3. By adjusting the field rheostat, the machine is brought to its rated speed.
4. The armature current, field current and voltage readings are noted.
5. The field rheostat is then brought to minimum position DPST switch is opened.
36. 20EE012 – EEE- SRIT
MODEL GRAPH:
As a Generator
% η
As a Motor
OUTPUT POWER
P0 (W)
40. 20EE012 – EEE- SRIT
SPEED CONTROL OF DC SHUNT MOTOR
Ex.No. 5B
Date:
AIM:
To obtain speed control of DC shunt motor by
a. Varying armature voltage with field current constant.
b. Varying field current with armature voltage constant
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter (0-20) A MC 1
2 Voltmeter (0-300) V MC 1
3 Rheostats
1250, 0.8A
50, 3.5A
Wire
Wound
Each 1
4 Tachometer (0-3000) rpm Digital 1
5 Connecting Wires 2.5sq.mm. Copper Few
PRECAUTIONS:
1. Field Rheostat should be kept in the minimum resistance position
2. Armature Rheostat should be kept in the maximum resistance position
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the maximum position of armature rheostat and minimum position
of field rheostat, DPST switch is closed
(i) Armature Control:
1. Field current is fixed to various values and for each fixed value, by varying the
armature rheostat, speed is noted for various voltages across the armature.
(ii) Field Control:
1. Armature voltage is fixed to various values and for each fixed value, by adjusting
the field rheostat, speed is noted for various field currents.
2. Bringing field rheostat to minimum position and armature rheostat to maximum
position DPST switch is opened.
41. 20EE012 – EEE- SRIT
TABULAR COLUMN:
(i) Armature Voltage Control:
S.No.
If1 = If2 = If3 =
Armature
Voltage
Va ( Volts)
Speed
N (rpm)
Armature
Voltage
Va ( Volts)
Speed
N (rpm)
Armature
Voltage
Va ( Volts)
Speed
N (rpm)
(ii) Field Control:
S.No.
Va1 = Va2 = Va3 =
Field
Current
If (A)
Speed
N (rpm)
Field
Current
If (A)
Speed
N (rpm)
Field
Current
If (A)
Speed
N (rpm)
MODEL GRAPHS:
If1
If2
If3
Va (Volts)
Va1
Va3 Va2
If (Amps)
Speed
N
(rpm)
Speed
N
(rpm)
42. 20EE012 – EEE- SRIT
RESULT:
Thus the speed control of DC Shunt Motor is obtained using Armature and Field
control methods.
43. 20EE012 – EEE- SRIT
Viva Questions:
1. State the advantage of Swinburne’s test.
2. Is it possible to conduct Swinburne’s test on DC series motor? Justify.
3. State the Torque equation of DC motor.
4. Which one of the speed will be higher either no-load speed or full load speed?
5. What will be the efficiency of the motor at no-load?
6. What will be the approximate value of armature and field resistance of DC
motors?
7. Why the armature control method is employed only below the rated speed in DC
shunt motors?
8. Why the field control method is employed only above the rated speed in DC
shunt motors?
9. Where we use shunt motor?
10.Why is field control method superior to armature control method for DC shunt
motors?
45. 20EE012 – EEE- SRIT
Ex.No. 6
Date:
HOPKINSON’S TEST
AIM:
To conduct Hopkinson’s test on a pair of identical DC machines to pre-determine
the efficiency of the machine as generator and as motor.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter
(0-1)A
(0-20) A
MC
MC
1
2
2 Voltmeter
(0-300) V
(0-600)V
MC
MC
1
1
3 Rheostats 1250, 0.8A
Wire
Wound
2
4
Tachometer
(0-3000) rpm Digital 1
5
Resistive Load
5KW,230V - 1
6
Connecting Wires
2.5sq.mm. Copper Few
FORMULAE:
Input Power = VI1 watts
Motor armature cu loss = (I1+ I2)2
Ra watts
Generator armature cu loss = I2
2 Ra watts
Total Stray losses W = V I1 - (I1+I2)2
Ra + I2
2 Ra watts.
Stray loss per machine = W/2 watts.
46. 20EE012 – EEE- SRIT
TABULAR COLUMN:
S.
No
Supply
Voltage
V
(Volts)
I1
(Amp)
I2
(Amp)
I3
(Amp)
I4
(Amp)
I1 + I2
(Amp)
Motor
Arma
ture
Cu Loss
W
(watts)
Generat
or
Arma
ture
Cu Loss
W (watt)
Total
Stray
losses
W
(watt)
Stray
Loss
Per
M/c
w/2
(watt)
AS MOTOR:
S.No
V
(Volt)
I1
(Amp)
I2
(Amp)
I3
(Amp)
Motor
Armatu
re
Cu Loss
W
(Watts)
Field
Loss
(Watt)
stray
losses
/2
(Watt)
Total
Losses
W
(Watt)
O/P
Powe
r
(Watt
)
I/P
Powe
r
(Watt
)
Effi
cien
cy
%
AS GENERATOR:
S.No.
V
(Volt)
I1
(Amp)
I2
(Amp)
Motor
Armatu
re
Cu Loss
W
(Watts)
Field
Loss
(Watts)
Stray
losses
/2
(Watt)
Total
Losses
W
(Watt)
Output
Power
(Watts)
Input
Power
(Watt)
Efficiency
%
47. 20EE012 – EEE- SRIT
2 4
AS MOTOR:
Input Power = Armature input + Shunt field input
= (I1+ I2) V + I3V = (I1+I2+I3) V
Total Losses = Armature Cu loss + Field loss + stray loss
= (I1 + I2)2
Ra + VI3 + W/2 watts
Input power – Total Losses
Efficiency % = ------------------------------------- x 100%
Input Power
AS GENERATOR:
Output Power = VI2 watts
Total Losses = Armature Cu loss+ Field Loss + Stray loss
= I 2
Ra + VI + W/2 watts
Output power
Efficiency % = --------------------------------------- x 100%
Output Power+ Total Losses
PRECATUIONS:
1. The field rheostat of the motor should be in the minimum position at the time
of starting and stopping the machine.
2. The field rheostat of the generator should be in the maximum position at the
time of starting and stopping the machine.
3. SPST switch should be kept open at the time of starting and stopping the
machine.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the minimum position of field rheostat of motor, maximum
position of field rheostat of generator, opening of SPST switch, DPST switch
is closed and starting resistance is gradually removed.
3. The motor is brought to its rated speed by adjusting the field rheostat of the
motor.
4. The voltmeter V1 is made to read zero by adjusting field rheostat of generator
and SPST switch is closed.
48. 20EE012 – EEE- SRIT
MODEL GRAPH:
% η
OUTPUT POWER P0 (W)
As a Generator
As a Motor
49. 20EE012 – EEE- SRIT
5. By adjusting field rheostats of motor and generator, various Ammeter
readings, voltmeter readings are noted.
6. The rheostats and SPST switch are brought to their original positions and
DPST switch is opened.
RESULT:
Thus Hopkinson’s test is conducted on a pair of identical DC machines the efficiency of
the machine as generator and as motor are pre-determined.
50. 20EE012 – EEE- SRIT
Viva Questions:
1. What are the advantages of Hopkinson’s test over Swinburne’s test and
what are its limitations?
2. What is the function of no-voltage release (NVR) coil provided in a DC
motor starter?
3. How does a 4-point starter differ from 3-point starter?
4. What are the other names of Hopkinson’s test?
5. What are the advantages of Hopkinson’s test?
6. A DC motor fails to start when switched on. What could be the reasons and
remedies?
7. When does the armature of dc motor likely to get over-heated?
8. What is the function of interpoles?
9. How the interpoles are connected?
10.Name different methods of electrical braking of DC motors.
52. 20EE012 – EEE- SRIT
Ex.No. 7
Date:
LOAD TEST ON A SINGLE PHASE TRANSFORMER
AIM:
To conduct load test on single phase transformer and to find efficiency and
percentage regulation.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter
(0-10)A
(0-5) A
MI
MI
1
1
2 Voltmeter
(0-150)V
(0-300) V
MI
MI
1
1
3 Wattmeter
(300V, 5A)
(150V, 5A)
Upf
Upf
1
1
4 Auto Transformer 1, (0-260)V - 1
5 Resistive Load 5KW, 230V - 1
6 Connecting Wires 2.5sq.mm Copper Few
FORMULAE:
Output Power = W2 x Multiplication factor
Input Power = W1 x Multiplication factor
Output Power
Efficiency % =----------------------x 100%
Input Power
VNL - VFL (Secondary)
Regulation R % =--------------------------------- x 100%
VNL
53. 20EE012 – EEE- SRIT
TABULAR COLUMN:
S.
N
o.
Loa
d
Primary Secondary Input
Power
W1 x
MF
Output
Power
W2 x
MF
Efficien
cy
%
%
Regu
latio
n
V1
(Volts)
I1
(Amp)
W1
(Watt)
V2
(Volt)
I2
(Amp)
W2
(Watt)
1.
2.
3.
4.
5.
6.
7.
8.
MODEL GRAPHS:
R
Efficiency
%
Regulation
R
%
55. 20EE012 – EEE- SRIT
PRECAUTIONS:
1. Auto Transformer should be in minimum position.
2. The AC supply is given and removed from the transformer under no load
condition.
PROCEDURE:
1. Connections are made as per the circuit diagram.
2. After checking the no load condition, minimum position of auto transformer and
DPST switch is closed.
3. Ammeter, Voltmeter and Wattmeter readings on both primary side and
secondary side are noted.
4. The load is increased and for each load, Voltmeter, Ammeter and Wattmeter
readings on both primary and secondary sides are noted.
5. Again no load condition is obtained and DPST switch is opened.
RESULT:
Thus the load test on single phase transformer is conducted.
56. 20EE012 – EEE- SRIT
Viva Questions:
1. What is the function of a transformer?
2. What is a load?
3. Why do we perform load test when the efficiency can be determined by O.C. and
S.C. tests?
4. Mention the types of transformer.
5. Explain the operating principle of a transformer.
6. List out general applications of transformer.
7. What are core type transformers?
8. What are shell type transformers?
9. Distinguish between power and distribution transformer.
10.Define voltage regulation of a transformer.
58. 20EE012 – EEE- SRIT
Ex.No. 8
Date:
OPEN CIRCUIT & SHORT CIRCUIT TEST ON A
SINGLE PHASE TRANSFORMER
AIM:
To predetermine the efficiency and regulation of a transformer by conducting
open circuit test and short circuit test and to draw equivalent circuit.
APPARATUS REQUIRED:
S.No. Apparatus Range Type Quantity
1 Ammeter
(0-2)A
(0-5) A
MI
MI
1
1
2 Voltmeter (0-150)V MI 2
3 Wattmeter
(150V, 5A)
(150V, 5A)
LPF
UPF
1
1
4 Connecting Wires 2.5sq.mm Copper Few
FORMULAE:
Core loss: Wo = VoIo cos o
Wo Wo
cos o = ------- o = cos-1
-------
Vo Io Vo Io
I = Io cos o (Amps) I = Io sin o (Amps)
o
R02
Ro1 = ----------------
K2
Ro =
V0
------- Xo =
V0
------- Ro2 =
Wsc
-------
I I Isc
2
Zo2 =
Vsc
-------
Isc
Xo2 = ( Z 2
- Ro2
2
)1/2
61. 20EE012 – EEE- SRIT
Percentage Efficiency: for all loads and p.f.
Output Power (X) x KVA rating x 1000 x cos
Efficiency % = =
Input Power Output power + losses
(X) x KVA rating x 1000 x cos
=
(X) x KVA rating x 1000 x cos + Wo + X2
Wsc
Percentage Regulation:
(X) x Isc (Ro2 cos Xo2sin ) x 100
R% =
V2
+ - lagging
- - leading
Where X is the load and it is 1 for full load, ½ for half load, ¾ load, ¼ load etc.. and
the power factor is, upf, o.8 p.f lag and 0.8 p.f lead
62. 20EE012 – EEE- SRIT
TABULAR COLUMN:
OPEN CIRCUIT TEST:
Vo
(Volts)
Io
(Amps)
Wo
(Watts)
SHORT CIRCUIT TEST:
Vsc
(Volts)
Isc
(Amps)
Wsc
(Watts)
EQUIVALENT CIRCUIT:
ISCo Ro1 Xo
R
Io
Vo
Ro Xo
ZL = ZL/K2
L
O
A
D
64. 20EE012 – EEE- SRIT
PRECAUTIONS:
1. Auto Transformer should be in minimum voltage position at the time of closing &
opening DPST Switch.
PROCEDURE:
OPEN CIRCUIT TEST:
1. Connections are made as per the circuit diagram.
2. After checking the minimum position of Autotransformer, DPST switch is closed.
3. Auto transformer variac is adjusted get the rated primary voltage.
4. Voltmeter, Ammeter and Wattmeter readings on primary side are noted.
5. Auto transformer is again brought to minimum position and DPST switch is
opened.
SHORT CIRCUIT TEST:
1. Connections are made as per the circuit diagram.
2. After checking the minimum position of Autotransformer, DPST switch is closed.
3. Auto transformer variac is adjusted get the rated primary current.
4. Voltmeter, Ammeter and Wattmeter readings on primary side are noted.
5. Auto transformer is again brought to minimum position and DPST switch is
opened.
65. 20EE012 – EEE- SRIT
Output power (Watts)
% lagging
Power factor
% leading
MODEL GRAPHS:
Efficiency
%
66. 20EE012 – EEE- SRIT
RESULT:
Thus the efficiency and regulation of a transformer is predetermined by
conducting open circuit test and short circuit test and the equivalent circuit is drawn.
68. 20EE012 – EEE- SRIT
SUMPNER’S TEST
Ex.No. 9
Date:
AIM :
To predetermine the efficiency and regulation of a given single phase Transformer
by conducting back-to-back test and also to find the parameters of the equivalent circuit.
APPARATUS REQUIRED:
S. No. Name of the Apparatus Range Type Quantity
1 Auto Transformer (0-270) V - 2
2 Wattmeter
300 V, 10A
75 V, 5 A
LPF
UPF
1
1
3 Ammeter
(0-2) A
(0-20) A
MI
MI
1
1
4 Voltmeter
(0-75) V
(0-150) V
MI
MI
1
1
5 Connecting Wires 2.5sq.mm Copper Few
FORMULAE:
W1
Core loss of each transformer Wo =------ Watts
2
W2
Full load copper loss of each transformer Wc = -------Watts.
2
Wo = V1I1 Cos o
Wo
o = Cos-1
---------
Io
I1 = ---- A
V1 I1 2
Iw = I1 Coso Iμ = I1 Cos V2 = Vs/2 x A
Ro = V1 / Iw Xo = V1 / Iμ Ro2 = Wc / I22
Zo2 = V2 / I2
Xo2 = Zo2
2 – Ro2
2 Copper loss at various loads = I2
2 Ro2
69. 20EE012 – EEE- SRIT
Io
Vo
Xo
Ro
L
O
A
D
EQUIVALENT CIRCUIT:
ISCo Ro1 Xo1
R
N
70. 20EE012 – EEE- SRIT
PERCENTAGE REGULATION:
1. Upf : I2 / V (Ro2 Coso) X 100
2. Lagging pf : I2 / V (Ro2 Coso + Xo2Sino) X 100
3. Leading pf : I2 / V (Ro2 Coso - Xo2Sino) X 100
Output Power (1) Upf : 3Kw
(2) Pf : 3Kw Coso
Input Power = Output Power + Core loss + Cu loss
Output power
Efficiency % = --------------------------- X 100%
Input Power
PRECAUTIONS:
1. Auto Transformer whose variac should be in zero position, before switching on
the ac supply.
2. Transformer should be operated under rated values.
PROCEDURE:
1. Connections are made as shown in the circuit diagram.
2. Rated voltage of 110V is adjusted to get in voltmeter by adjusting the variac of
the Auto Transformer which would be in zero before switching on the supply at
the primary side.
3. The readings of voltmeter, ammeter and wattmeter are noted on the primary
side.
4. A voltmeter is connected across the secondary and with the secondary supply off
i.e switch S is kept open. The voltmeter reading is noted.
5. If the reading of voltmeter reads higher voltage, the terminals of any one of
71. 20EE012 – EEE- SRIT
secondary coil is interchanged in order that voltmeter reads zero.
72. 20EE012 – EEE- SRIT
MODEL GRAPHS:
Cos = 1
Cos = 0.8 (Lead &
Lag
Cos = 1
Cos = 0.8 Lag
Cos = 0.8 Lead
Secondary Current (Amps) Secondary Current (Amps)
%
Efficiency
%
Regulation
73. 20EE012 – EEE- SRIT
6. The secondary is now switched on and SPST switch is closed with variac of auto
transformer is zero.
7. After switching on the secondary the variac of transformer (Auto) is adjusted so
that full load rated secondary current flows.
8. Then the readings of wattmeter, Ammeter and voltmeter are noted.
9. The Percentage Efficiency and percentage regulation are calculated and
equivalent circuit is drawn.
RESULT:
Thus the efficiency and regulation of a given single phase Transformer is carried
out by conducting back-to-back test and the equivalent circuit parameters are found out.
75. 20EE012 – EEE- SRIT
SEPARATION OF NO LOAD LOSSES IN A SINGLE PHASE
TRANSFORMER
Ex.No. 10
Date:
AIM:
To separate the eddy current loss and hysteresis loss from the iron loss of single
phase transformer.
APPARATUS REQUIRED:
S. No. Name of the Apparatus Range Type Quantity
1 Rheostat 1250Ω , 0.8A Wire Wound 2
2 Wattmeter 300 V, 5A LPF 1
3 Ammeter (0-2) A MC 1
4 Voltmeter (0-300) V MI 1
5 Connecting Wires 2.5sq.mm Copper Few
FORMULAE:
1. Frequency, f =(P*NS) / 120 in Hz
P = No.of Poles Ns = Synchronous speed in rpm.
2. Hysteresis Loss Wh = A * f in Watts
A = Constant (obtained from graph)
3. Eddy Current Loss We = B * f2
in Watts
B = Constant (slope of the tangent drawn to the curve)
4. Iron Loss Wi = Wh + We in Watts
5. Wi / f = A + (B * f)
Here the Constant A is distance from the origin to the point where the line cuts
the Y- axis in the graph between Wi / f and frequency f. The Constant B is
Δ(Wi / f ) / Δf
76. 20EE012 – EEE- SRIT
TABULAR COLUMN:
S.No Speed
N (rpm)
Frequency
f (Hz)
Voltage
V (Volts)
Wattmeter
reading
Watts
Iron loss
Wi (Watts)
Wi / f
Joules
1.
2.
3.
4.
5.
MODEL GRAPH:
Wf
A
y
x
78. 20EE012 – EEE- SRIT
PRECAUTIONS:
1. The motor field rheostat should be kept at minimum resistance position.
2. The alternator field rheostat should be kept at maximum resistance position.
PROCEDURE:
1. Connections are given as per the circuit diagram.
2. Supply is given by closing the DPST switch.
3. The DC motor is started by using the 3 point starter and brought to rated speed
by adjusting its field rheostat.
4. By varying the alternator filed rheostat gradually the rated primary voltage is
applied to the transformer.
5. The frequency is varied by varying the motor field rheostat and the readings of
frequency are noted and the speed is also measured by using the tachometer.
6. The above procedure is repeated for different frequencies and the readings are
tabulated.
7. The motor is switched off by opening the DPST switch after bringing all the
rheostats to the initial position.
RESULT:
Thus separation of eddy current and hysteresis loss from the iron loss on asingle-
phase transformer is conducted.
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