PREPARATORY NOTE FOR   QUIZ, TEST & EXAMINATION   PASS WITHOUT TEAR.   COURSE CODE   EEC 233   COURSE TITLE   (ELECTRICAL MACHINES II)   SYNCHRONOUS MACHINE (SYNCHRONOUS MOTOR)   CREDIT UNIT: 3   SACRIFICE AND HARDWORKING SPEAK  AT  LAST IN OUR SCRIPT BY HENRY PRECIOUS AMAMINA MAY 9TH 2023. TABLE OF CONTENT   TITLE PAGE   TABLE OF CONTENT   CHAPTER ONE   ? DEFINITION OF SYNCHRONOUS MACHINE   ? IMPORTANT OF SYNCHRONOUS MACHINE/MOTOR   ? ADVANTAGE OF SYNCHRONOUS MACHINE/MOTOR   ? TYPE OF SYNCHRONOUS MACHINE   ? OPERATING PRINCIPLE OF SYNCHRONOUS GENERATOR   ? OPERATING PRINCIPLE OF SYNCHRONOUS MOTOR   ? DIFFERENCE BETWEEN STATOR & ROTOR   ? EXCITATION METHOD   ? DIRECT CONNECTED EXCITERS   ? CONTROL & PROTECTION OF ELECTRIC MOTORS   ? VARIABLE SPEED DRIVE SYSTEM   ? THYRISTOR   ? THYRATRON(IGNITRONS MERCURY)   ? THYRISTOR CONTROLLED DRIVE   ? NEED FOR CIRCUIT PROTECTION ADVANTAGE OF    THYRISTOR   CHAPTER TWO   ? ENERGY CONVERSION   ? USE OF ENERGY   ? ELECTROMECHANICAL ENERGY CONVERSION   ? ELECTROMECHANICAL ENERGY CONVERSION PRINCIPLE   ? ENERGY CONVERSION PRINCIPLE   ? ENERGY STORAGE   ? ACCUMULATOR (BATTERY)   ? ENERGY DENSITY   ? TYPE OF ENERGY STORED CHAPTER THREE   ? CONSTANT CURRENT   ? IMPORTANT OF CONSTANT CURRENT   ? DIFFERENTIAL FORM (DIFFERENT INDUCTION MACHINE)   ? FARADAY LENZ LAW   ? MAXWELL STRESS   CHAPTER FOUR   ? TRANSFORMER   ? FUNCTION OF TRANSFORMER   ? TYPE OF TRANSFORMER CORES AND WINDING   ? TYPE OF TRANSFORMER   ? COMPARISON BETWEEN THE CORE TYPE & SHELL TYPE    TRANSFORMER   ? EQUIVALENT CCT OF A TRANSFORMER   ? ELECTROMAGNETIC   ? LIMITATION OF THE EQUIVALENT CIRCUIT &    APPROXIMATE   ? CONNECT 3 SINGLE PHASE TRANSFORMER FOR 3PHASE    OPERATION   ? STAR/STAR CONNECTION   ? ADVANTAGE OF STAR CONNECTION   ? DISADVANTAGE   ? STAR/DELTA CONNECTION   ? DIFFERENCE BETWEEN POWER & DISTRIBUTION    TRANSFORMER   ? IMPORTANCE OF POWER TRANSFORMER   ? FUNCTION OF POWER TRANSFORMER   ? DISTRIBUTION TRANSFORMER   ? FUNCTION OF DISTRIBUTION TRANSFORMER   ? EFFECT OF TEMPERATURE RISE ON TRANSFORMER   ? FUNCTION OF TRANSFORMER   ? METHOD OF COOLING TRANSFORMER   ? DISADVANTAGE OF COOLING METHOD   ? COOLING METHOD FOR OIL IMMERSED TYPE    TRANSFORMER   ? ADVANTAGE OF METHOD OF COOLING? ESSENTIAL FACTORS FOR NOISE PRODUCTION IN    TRANSFORMER   CHAPTER FIVE   ? NOISE EMISSION   ? CONSTRUCTIONAL FEATURES (NOISE EMISSION)   ? TAP CHANGING IN VOLTAGE CONTROL   ? VOLTAGE VARIATION IN POWER SYSTEM   ? PRINCIPLE OF REGULATING VOLTAGE   ? REASON FOR PROVIDING TAPPING   ? CAUSES OF HARMONICS IN TRANSFORMER   ? MAGNITUDE & FREQUENCY HARMONIC   ? OVER CURRENT & OVER CURRENT PROTECTIVE DEVICES   ? TYPE OF CURRENT FLOW IN AN ELECTRICAL CIRCUIT   ? FUSE   ? CIRCUIT BREAKER   ? RELAY    ? TYPE OF ELECTROMECHANICAL RELAY   ? SELECTOR SWITCHES   ? INDICATOR LIGHT   ? LED INDICATOR   ? NON FLASHING LED INDICATOR LIGHT   ? PUSH BUTTON   ? TERM FOR THE PUSHING OF A BUTTON   ? CONTACTOR   ? ENERGY BALANCE   ? SYNCHRONOUS MACHINE CONSTITUTE OF BOTH    GENERATOR & MOTOR CHAPTER ONE   ELECTRICAL MACHINE II   (EEC233)   SYNCHRONOUS MACHINE (SYNCHRONOUS MOTOR)   DEFINITION:   A Synchronous machine is an a.c machine in which the rotor moves at a    speed which bears a constant relationship to the frequency of the    current in armature winding.   Note:    A synchronous machine is one of the important type of electric    machine.   IMPORTANT OF SYNCHRONOUS MACHINE/ MOTOR   a. It provides constant speed industrial (drives with).   b. It has a driving possibility of power factor correction.   ADVANTAGE OF SYNCHRONOUS MACHINES/ MOTOR   a. They are generally constructed in larger sizes.   b. Small size alternators are not economical. The best is to build    alternators of very large sizes capable of generating 500MVA or    more.   TYPE OF SYNCHRONOUS MACHINE   The synchronous machine consists of two parts namely below:   1. The armature ( or stator) and,   2. The field magnet(ic) system (or rotor).Armature (Stator): Is an iron ring, formed of lamination of    special magnetic iron or steel alloy having slots on it periphery to    accommodate armature conductor (stator).   - Note:    The whole structure is held in a frame which may be cast iron    or welded steel plate.   USE OF SLOT IN ARMATURE (STATOR)   a. The open slots are more commonly used because the coils can be    form – wound and insulated, before being placed in the slots    giving least expenditure and more satisfactory winding method.   b. The slots facilitate the removal and replacement of effective coils.   c. Number of slots per pole per phase should be large to give    sinusoidal generated emf.   - Note:    General the number of slots per pole per phase is three to    four for small machine and more than five for large    machine.   SMALL MACHINE: Using three to four slot per pole per phase   LARGE MACHINE: Using more than five slots per pole phase.   2. FIELD MAGNET SYSTEM (ROTOR): It provide the generation of    alternating voltage similar to those of a d.c machine which is    supplied with direct current.   - Note:    A small d.c generator is installing for the purpose of making the    alternator self – contained and independent of other sources of    supply ? Generator: It is called the exciter. Exciter is coupled to the    engine driving the alternator.   ? Exciter armature: Is completed directly to the alternator field    winding, usually without any kind of controlling resistance.   - Note:    The resistance of the exciter load is constant for the successful    operation of alternator.   The field magnet system of the alternator is rotated with in the    armature ring and is known as rotor.   The exciting current is supplied to the rotor through two slip – rings and    brushes. There a polarity of the field produced is alternately:   a. North (N)   b. South (S)   USE OF EXCITER IN FIELD MAGNET SYSTEM (ROTOR)   i. Both exciter and synchronous generator have the same power    rating of 0.5 to 1%.   ii. Its voltage rating is usually between 125 to 250volt.   - Note:    In case of large synchronous machine of the power rating of    few hundred 19w, the excitation need become very large and    the problem of supplying such amount of power through high    speed sliding contacts become acute.   OPERATING PRINCIPLE OF SYNCHRONOUS GENERATOR   The operating principle of a synchronous machine/ generator is  Note:   But unlike the latter, in the synchronous machine, there is no    need to rectify the time varying emf, which is induced in the    armature winding.   OPERATING PRINCIPLE OF SYNCHRONOUS MOTOR   The action of a synchronous motor is the same to that of a three –   phase, two – pole synchronous machines.   - Note:    The rotor has two poles and the stator has two poles per phase.   The rotor rotate in clockwise direction when the S – pole attract    the N – pole.   In practice it is usual to have salient pole on the rotor. But the    armature winding is house in slots in the concave periphery of    the stator.   DIFFERENT BETWEEN STATOR AND ROTOR   a. The polarity of stator pole is reversed while   b. Rotor: the polarity of rotor pole remained the same.   - Note:   At this instant the rotor S – pole is repelled by the stator, S –   pole being similar nature.    Question: How does repelling occur between the rotor S – pole and    stator S – pole.   - EXCITATION METHOD: In a d.c motor, the field and armature    both are supplied from d.c supply mains. fundamentally the same as that of d.c machine.Note:   But unlike the latter, in the synchronous machine, there is no    need to rectify the time varying emf, which is induced in the    armature winding.   OPERATING PRINCIPLE OF SYNCHRONOUS MOTOR   The action of a synchronous motor is the same to that of a three –   phase, two – pole synchronous machines.   - Note:    The rotor has two poles and the stator has two poles per phase.   The rotor rotate in clockwise direction when the S – pole attract    the N – pole.   In practice it is usual to have salient pole on the rotor. But the    armature winding is house in slots in the concave periphery of    the stator.   DIFFERENT BETWEEN STATOR AND ROTOR   a. The polarity of stator pole is reversed while   b. Rotor: the polarity of rotor pole remained the same.   - Note:   At this instant the rotor S – pole is repelled by the stator, S –   pole being similar nature.    Question: How does repelling occur between the rotor S – pole and    stator S – pole.   - EXCITATION METHOD: In a d.c motor, the field and armature    both are supplied from d.c supply mains. Synchronous motor the field structure is to be energized by direct    current.   Alternator the armature winding is connected to a three – phase a.c   supply mains   - Note:   D.c excitation may be provided either from an exciting plant d.c    system or if no direct current is available.   DIRECT CONNECTED EXCITERS   Are frequently found on high speed motors (high loaded vehicle)   CONTROL AND PROTECTION OF ELECTRIC MOTOR:   Electric motors are employed in a very large power range from a few    watts to thousand kilowatts.   - Note:    Many applications require very precise position adjustment (as    in robotics). In many applications optimum performance and    efficiency are the main concern.   ? VARIABLE SPEED DRIVE SYSTEM: This help in optimization of    process so as to reduce investment cost, operational cost and    maintenance costs.   - Note:   Energy savings is another big advantage of variable speed    drives.   ? Thyristors: This is capable of handling large currents has    revolutionalized the field of electric power control. Thyratrons: (Ignitrons, mercury): These are rectifiers magnetic    amplifiers, motor generator sets have all been replaced by solid    state circuit employing semiconductor diodes and thyristors.   ? Thyristor controlled drives: This employing both d.c and a.c   motor find wide application in industry as variable speed drives.   - Note:   In 1960 a.c power used to be converted to d.c power for direct    control of drive.   Motors with solid state device (high power silicon diodes and    silicon controlled rectifier.   Initially saturable reactors were employed in conjunction with    high power silicon rectifier for d.c drives.   Nowadays thyristors are extensively used for a.c to d.c    conversion.   NEEDS FOR CIRCUIT PROTECTION ADVANTAGE OF THYRISTOR   1. The response of the thyristor control device is faster   - Note:   As it eliminate the time lag introduced by the inductances of    the generator field and the armature.   2. It has high efficiency of the control system due to low voltage drop    across thyristor   3. The control devices are smaller in size, lighter in weight.   4. The control device is cheaper in cost, requiring less space and    minimal maintenance   5. Simple and reliable operation.