Electrical Machine-I PPT

1. -Mr. M.N. Mestri
Department of Electrical Engineering,
ATS’S Sanjay Bhokare Group of Institutes,
Miraj.
mnmestri@gmail.com /
mestrimn@sbgimiraj.org
Electrical Machine-I

2. I. Single Phase Transformer. (7 Hours)
II. Three Phase Transformers. (8 Hours)
III. Electromechanical Energy Conversion Principles. (6 Hours)
IV. DC Generators. (9 Hours)
V. DC Motors. (9 Hours)
VI. Special Machines. (6 Hours)
Syllabus Contents
-Mr. M.N. Mestri 2

3.  Transformer construction,
 Ideal and practical transformer, Exact and approximate
equivalent circuits,
 No load and on load operation, phasor diagrams,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Lecture 1st
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 3

4. What is Transformer?
A transformer is defined as a passive electrical device that
transfers electrical energy from one circuit to another through the
process of electromagnetic induction and by changing Voltage and
Current Level in Circuit with Frequency Constant.
Definition of Transformer
-Mr. M.N. Mestri 4

5. Classification of Transformers: (Depending on Operation)
-Mr. M.N. Mestri 5
Transformers
Single Phase
Transformer
Three Phase
Transformer
Isolation
Transformers
Auto-Transformer
V-I Transformer
Welding
Transformer
Pulse Transformer
Low Tension
Transformer
1:1 Ratio
Transformer
High Tension/Power
Transformer
Auto-Transformer
Tap-Changer
Transformer
Step-Down: Secondary (Output)
Voltage is Less than Primary
(Supply) Voltage (E1>E2)
All Types of Transformers are
Step-Up and Step-Down
Step-Up: Secondary (Output)
Voltage is Higher than Primary
(Supply) Voltage (E1<E2)
Isolation: Secondary (Output)
Voltage is Equal to Primary
(Supply) Voltage (E1=E2)

6. Classification of Transformers: (Depending on Core Type)
-Mr. M.N. Mestri 6
Transformers
Core Type
Transformer
Shell Type
Transformer
Berry Type
Transformer

7. Classification of Transformers: (Depending on Winding Type)
-Mr. M.N. Mestri 7
Transformers
Helical Winding
Transformer
Cross-Over
Transformer
Disc Type
Transformer
Sandwich Type
Transformer

8. Construction of Transformer:
-Mr. M.N. Mestri 8

9. Winding Types:
-Mr. M.N. Mestri 9

10. -Mr. M.N. Mestri 10
Thank You…

11.  Transformer construction,
 Ideal and practical transformer, No load phasor diagrams
 On load operation phasor diagrams,
 Exact and approximate equivalent circuits,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Lecture 2nd
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 11

12. Classification of Ideal and Practical Transformer:
-Mr. M.N. Mestri 12
Transformers
Source
Current Source Voltage Source
Ideal Transformer
Practical
Transformer
Practical Transformers: Whose
output is less than 100%
efficiency due to losses.
Ideal and Practical Transformers
are Step-Up and Step-Down
Ideal Transformers: Whose
output is with 100% efficiency
without any losses.
Ideal Transformer
Practical
Transformer

13. Ideal Transformers:
Whose output is with 100% efficiency without any losses.
Ideal Transformer. (No-Load with Phasor Diagram)
-Mr. M.N. Mestri 13

14. Practical Transformers:
Whose output is less than 100% efficiency due to losses.
Practical Transformer. (No-Load with Phasor Diagram)
-Mr. M.N. Mestri 14

15. Practical Transformers Losses:
Losses in Practical Transformer.
-Mr. M.N. Mestri 15
Transformers
Losses
Iron Losses
(in Core)
Copper Losses
(in Winding)
Magnetic Losses
(due to Leakage Flux)
We use Laminated Core
We use Pure Winding
Conductor
Making Proper Stamping
between Laminations

16. -Mr. M.N. Mestri 16
Thank You…

17.  Transformer construction,
 Ideal and practical transformer, No load phasor diagrams
 On load operation phasor diagrams,
 Exact and approximate equivalent circuits,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Lecture 3rd
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 17

18. Transformation Ratio:
(I2/I1) = (N1/N2) = (E1/E2) = K
Power Between Primary and Secondary:
E1I1 = E2I2 => P1 = P2
Parameters for Loading of Ideal Transformer.
-Mr. M.N. Mestri 18

19. Loads:
Types of Loads.
-Mr. M.N. Mestri 19
Types of Loads Inductive
Resistive
Capacitive
Lagging Power Factor
(I Lags V)
Unity Power Factor
(I is in Phase with V)
Leading Power Factor
(I Leads V)

20. Ideal Transformers on Lagging Power Factor:
Whose output is with 100% efficiency without any losses.
Ideal Transformer. (On-Load with Phasor Diagram)
-Mr. M.N. Mestri 20

21. Ideal Transformers on Unity Power Factor:
Whose output is with 100% efficiency without any losses.
Ideal Transformer. (On-Load with Phasor Diagram)
-Mr. M.N. Mestri 21

22. Ideal Transformers on Leading Power Factor:
Whose output is with 100% efficiency without any losses.
Ideal Transformer. (On-Load with Phasor Diagram)
-Mr. M.N. Mestri 22

23.  Transformer construction,
 Ideal and practical transformer, No load phasor diagrams
 On load operation phasor diagrams,
 Exact and approximate equivalent circuits,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Lecture 4th
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 23

24. Practical Transformers:
Whose output is less than 100% efficiency due to losses.
Practical Transformer. (On-Load Figure)
-Mr. M.N. Mestri 24
Φ= Main Flux
Φ2= Flux due to Secondary
Current I2
Φ2’= Compensatory Flux by
Primary Winding due to
Increase in Primary Current
ZL= Load Impedance

25. Practical Transformer. (On-Load Equivalent Circuit Diagram)
-Mr. M.N. Mestri 25
 Equivalent or Exact Circuit Diagram

26. Practical Transformer. (On-Load Equivalent Circuit Diagram)
-Mr. M.N. Mestri 26
Primary Parameters Secondary Parameters
V1= Primary Voltage
I1= Primary Current
R1= Primary Resistance
X1= Primary Reactance
Iw= Core Loss Component of Io
Im= Magnetizing Component of Io
Io= No Load Primary Current
I2’= Component of I1 to Reduce φ2 effect
Ro= Core Loss Resistance
Xo= Magnetizing Reactance
N1= Primary Turns
E1= Primary Induced EMF
V2= Terminal Voltage
I2= Secondary Current
R2= Secondary Resistance
X2= Secondary Leakage Reactance
N2= Secondary Turns
E2= Secondary Induced EMF

27. Practical Transformer. (On-Load Approximate Equivalent Circuit Diagram)
-Mr. M.N. Mestri 27
 Approximate Circuit Diagram Refer to Primary

28. Practical Transformer. (On-Load Equivalent Circuit Diagram)
-Mr. M.N. Mestri 28
 Approximate Circuit Diagram Refer to Primary
Transformation Ratio:
(I2/I1) = (N1/N2) = (E1/E2) = K
 Therefore, K= E2/E1 is considered to transfer secondary parameters
to primary.
 Therefore, R2’= R2/K2
 Similarly, X2’= X2/K2

29. Practical Transformer. (On-Load Approximate Equivalent Circuit Diagram)
-Mr. M.N. Mestri 29
 Approximate Circuit Diagram Refer to Secondary

30. Practical Transformer. (On-Load Equivalent Circuit Diagram)
-Mr. M.N. Mestri 30
 Approximate Circuit Diagram Refer to Secondary
Transformation Ratio:
(I2/I1) = (N1/N2) = (E1/E2) = K
 Therefore, K= E2/E1 is considered to transfer secondary parameters
to primary.
 Therefore, R1’= R1 x K2
 Similarly, X1’= X1 x K2

31. Practical Transformer. (On-Load Approximate Equivalent Circuit Diagram)
-Mr. M.N. Mestri 31
 Simplified Circuit Diagram

32. Practical Transformer. (On-Load Equivalent Circuit Diagram)
-Mr. M.N. Mestri 32
 Approximate Circuit Diagram Refer to Secondary
Depending on referred side the simplified values can be determined
by,
 Therefore, Req= R1 + R2’ (or) Req= R1’ + R2
 Similarly, Xeq= X1 + X2’ (or) Xeq= X1’ + X2

33.  Transformer construction,
 Ideal and practical transformer, No load phasor diagrams
 On load operation phasor diagrams,
 Exact and approximate equivalent circuits,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Lecture 5th
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 33

34. What is Power (शक्ती)?
Power is defined as the rate at which a specific work is done, or
which the energy is transmitted.
What is Energy (ऊर्जा)?
Energy is defined as the capacity to do some work. It is power which
is integrated over time. (Dependent on Power)
Power (शक्ती) and Energy (ऊर्जा)
-Mr. M.N. Mestri 34

35. Power and Energy
-Mr. M.N. Mestri 35
Sr. No. Energy (ऊर्जा) Power (शक्ती)
1.
Energy is defined as the capacity to do some
work. It is power which is integrated over
time.
Power is defined as the rate at which a specific work is
done, or which the energy is transmitted.
2.
The unit used to measure energy is joules or
watt-seconds
The unit used to measure this is watt or joules per
second
3. ‘W’ is the symbol which denotes energy The symbol used to denote power is P.
4. Energy changes from one form to another Power cannot be transformed from one type to another
5. Energy is a time quantity or component It is an instantaneous quantity
6.
Various types of energy are kinetic, thermal,
potential, gravitational, sound,
electromagnetic, light, elastic, etc
Different kinds of power are electric power, optical
power, human power, etc.
7.
Energy is known to be stored which can be
used in future
Power quantity is not storable or cannot be stored
8.
Energy is used in moving a car, heating home,
lighting night, flying an aeroplane, etc.
Power finds its uses in mechanical applications, electrical
applications, heat applications, etc.

36. What is Efficiency?
 Efficiency signifies a peak level of performance that uses the least amount of
inputs to achieve the highest amount of output.
What is Energy Efficiency?
 Energy efficiency simply means using less energy to perform the same task – that
is, eliminating energy waste.
Example for Energy Efficiency?
 Energy efficiency is using technology that requires less energy to perform the
same function. Using a light-emitting diode (LED) light bulb or a compact
fluorescent light (CFL) bulb that requires less energy than an incandescent light
bulb to produce the same amount of light is an example of energy efficiency.
Efficiency (कजर्ाक्षमतज)
-Mr. M.N. Mestri 36

37. Formula for Efficiency?
It is a ratio between Output Power to the Input Power.
For Percentage Efficiency
Efficiency
-Mr. M.N. Mestri 37

38. What is Voltage Regulation?
The voltage regulation of the transformer is the percentage change
in the output voltage from no-load to full-load. And since power
factor is a determining factor in the secondary voltage, power factor
influences voltage regulation. This means the voltage regulation of a
transformer is a dynamic, load-dependent number.
Voltage Regulation
-Mr. M.N. Mestri 38

39. What is Parallel Operation?
The Transformer is said to be in Parallel Operation when its primary
winding is connected to a common voltage supply, and the secondary
winding is connected to a common load.
Parallel Operation of Transformer
-Mr. M.N. Mestri 39

40. What are the Reason for Parallel Operation?
 It is impractical and uneconomical to have a single large transformer for
heavy and large loads. Hence, it will be a wise decision to connect a
number of transformers in parallel.
 In substations, the total load required may be supplied by an appropriate
number of the transformer of standard size. As a result, this reduces
the spare capacity of the substation.
 If the transformers are connected in parallel, so there will be scope in
future, for expansion of a substation to supply a load beyond the capacity
of the transformer already installed.
 If there will be any breakdown of a transformer in a system of
transformers connected in parallel, there will be no interruption of power
supply, for essential services.
 If any of the transformer from the system is taken out of service for its
maintenance and inspection, the continuity of the supply will not get
disturbed.
Parallel Operation of Transformer
-Mr. M.N. Mestri 40

41. Necessary Conditions for Parallel Operation?
The Polarities of the transformers must be the same.
The Turn Ratio of the transformer should be equal.
Transformers must be identical.
Parallel Operation of Transformer
-Mr. M.N. Mestri 41

42.  Transformer construction,
 Ideal and practical transformer, No load phasor diagrams
 On load operation phasor diagrams,
 Exact and approximate equivalent circuits,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Lecture 6th
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 42

43. Effect of Loading on Power Transformer
-Mr. M.N. Mestri 43
I1= Primary Current
I2= Secondary Current
Effects
1. With increase in Load,
Secondary Current increases
and Active Power will get
increase
Active Power= V x I x P.F
2. To maintain Active Power at
Load Transformer will increase
Primary Current, which will be
known as Additional Primary
Current I2’.
Load increase -> I2 increase -> Pout increase
-> Pin increase -> I2’ increase -> V decrease

44. Per Unit System
-Mr. M.N. Mestri 44
 In a Power System we know, there are multiple devices connected
with each other and All devices are of different Ratings. i.e. some
are in MVA, KVA, VA, MVAR, KVAR and VAR.
 Per Unit System means, to convert all Devices Rating into a Single
Unit with

45. Effects:
Excitation Phenomenon of Transformer
-Mr. M.N. Mestri 45
Effects Eddy Current
Hysteresis Effect
Very Low and can be
Neglected
High

46. Excitation Phenomenon of Transformer
-Mr. M.N. Mestri 46
 The Current required to established the Flux in a magnetic circuit is
called the exciting current.
 The study of the excitation phenomenon in transformer means the
study of the nature of exciting current, voltage and Flux
transformer primary is energized with secondary winding open.

47. Excitation Phenomenon of Transformer (Characteristics)
-Mr. M.N. Mestri 47
 1. B-H Linear Curve till point “a” and slight curve in Flux after increase in Current.
 2. Flux is Sinusoidal but Current is Sinusoidal till Point “a” and having peaky
characteristics of Current with less increase in Flux.
 3. Current is Sinusoidal and having high peak but flux is flat after some point.

48. Excitation Phenomenon of Transformer (Characteristics)
-Mr. M.N. Mestri 48
 When we provide Negative 3rd Harmonics Pulse in Fundamental Waveform we
obtain Peaky Current Output.
 Conditions for Peaky Current Peaks

49. Excitation Phenomenon of Transformer (Characteristics)
-Mr. M.N. Mestri 49
 When we provide Positive 3rd Harmonics Pulse in Fundamental Waveform we
obtain Flat Current Output.
 Conditions for Flat Current Peaks

50. Excitation Phenomenon of Transformer (Characteristics)
-Mr. M.N. Mestri 50
 With B-H Curve

51. Switching Transients in Transformers
-Mr. M.N. Mestri 51
 When Switching operation is conducted on any Transformer, the initial Inrush
Current Starts to flow in Transformer which are known as Switching Transients
of Transformers.

52.  Transformer construction,
 Ideal and practical transformer, No load phasor diagrams
 On load operation phasor diagrams,
 Exact and approximate equivalent circuits,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Lecture 7th
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 52

53. Auto-Transformer
-Mr. M.N. Mestri 53
Parts: 1. Slider and 2. Coil
Position 1st Input = Output
Position 6th Input = Input/6
Use: To Control Supply Current and Voltage.

54. Variable Frequency Transformer
-Mr. M.N. Mestri 54
Definition: Variable frequency transformer (VFT) is a controllable
bidirectional transmission device that can transfer power between asynchronous
networks.
Use: To connect different frequencies.

55. Voltage and Current Transformer
-Mr. M.N. Mestri 55
Definition: The Voltage/Potential transformer converts the high value of
voltages into low voltage.
Use: At substation to control voltage and for fault analysis.

56. Voltage and Current Transformer
-Mr. M.N. Mestri 56
Parts: The Current transformer converts the high value of Current into low
Current.
Use: At substation to control current and for fault analysis.

57. Welding Transformer
-Mr. M.N. Mestri 57
Define: Welding Transformers are used in AC machines to change alternating
current from the power line into a low-voltage, high amperage current in the
secondary winding. To gain high current on secondary, voltage is dropped with the
help of adjustable knob.
Use: Welding to metals.

58. Pulse Transformer
-Mr. M.N. Mestri 58
Define: A pulse transformer is an enhanced transformer that produces
electrical pulses of great velocity and constant amplitude. They are often used in
the transmitting of digital information and in transistors (particularly with gate
drive circuits).
Use: In Electronics Circuits with Transistors to Produce Pulses.

59.  Transformer construction,
 Ideal and practical transformer, No load phasor diagrams
 On load operation phasor diagrams,
 Exact and approximate equivalent circuits,
 Power and energy efficiency, voltage regulation,
 Parallel operation,
 Effect of load on power factor, per unit system,
 Excitation phenomenon in transformers,
 Switching transients,
 Auto transformers, variable frequency transformer,
 Voltage and current transformers,
 Welding transformers,
 Pulse transformer and applications.
Chapter 1st: Conclusion
Single Phase Transformer (7 Hours)
-Mr. M.N. Mestri 59

60. -Mr. M.N. Mestri 60
Thank You…