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BEX – Basic Electricity – Unit 13. Magnetic Motors REF: Delmar’s Standard Textbook of Electricity , Unit 13. Magnetic Motors. Lesson Objectives: To understand the principles of magnetism as it applies to magnetic motors To identify the different types of motors
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BEX – Basic Electricity – Unit 13 Magnetic Motors REF: Delmar’s Standard Textbook of Electricity, Unit 13
Magnetic Motors • Lesson Objectives: • To understand the principles of magnetism as it applies to magnetic motors • To identify the different types of motors • To identify the various components of an electromagnetic motor
Magnetic Motors Magnetic properties • Unlike poles attract • Like poles repel • The basis for the operation for a motor
Magnetic Motors Magnetic properties • Current flow through a conductor creates a weak magnetic field • Wrapping a conductor increases the magnetic field
Magnetic Motors Magnetic Properties • When a current carrying conductor is placed inside of a magnetic field, the conductor moves towards the weaker magnetic field on the outside of the magnet
Magnetic Motors Components
Magnetic MotorsA Simple Electromagnetic Motor • Armature windings • Field windings • Pole shoes • Brushes • Commutator • Power source
Magnetic Motors • Field Coils & Pole Shoes: • Heavy copper wire wrapped in a coil • Surrounding an iron core • Forms an electromagnet
Magnetic Motors • The Armature: • Rotates within stationary field coils • Consists of heavy loops of insulated copper wire • Wraps around (and insulated from) a laminated iron core
Magnetic Motors • The Commutator: • A series of split ring copper segment bars • Forms a sliding contact area for brushes
Magnetic Motors • The Brushes: • Made of a mixture of carbon and copper • Used to conduct high amperage through armature windings
Magnetic Motors • Conductor/Field Coil Interaction: • Magnetic fields react by moving the conductor towards the weaker magnetic field • Armature rotates energizing the next contact on the commutator
Magnetic Motors • Counter Electromotive Force (CEMF): • Produced by electromagnetic induction in the windings • Tends to act against the supply voltage • Increases with motor speed • Reduces current/torque of motor
Magnetic Motors Types of motors
Magnetic Motors • Series Wound: • Current flows through the field windings • Then through the armature windings • Returns to ground • Maximum torque is developed during initial start up • CEMF increases with motor speed
Magnetic Motors • Parallel Wound: • Current flows in parallel to the field windings, positive brushes and commutator, armature, and grounding brushes • A low torque motor • Spins at lower speeds • CEMF does not increase with motor speed
Magnetic Motors • Compound Wound: • Most of the field coils are in series to the armature • One field coil is connected to ground • Combines the best properties of the series and the parallel wound motors • Motor has good initial torque and speed
Magnetic Motors • Permanent Magnet Motor: • Electromagnetic field coils are replaced with permanent magnets • Reduces the size and weight of motor • Uses less current
HOW DOES A MOTOR USE MAGNETISM? HOW IS ELECTRICAL ENERGY CONVERTED INTO MECHANICAL ENERGY? WHAT IS THE MOVEABLE, INTERNAL FIELD CALLED? WHAT IS THE STATIONARY OUTSIDE FIELD CALLED? NAME THREE WAYS OF CONNECTING THE 2 FIELDS ELECTRICALLY. REVIEW…..
WHAT IS COUNTER ELECTROMOTIVE FORCE? HOW DOES THE INTERNAL FIELD GETS IT’S POWER AND GROUND? HOW IS A TYPICAL STARTER MOTOR GROUNDED? HOW IS A PERMANENT MAGNET STARTER DIFFERENT FROM ELECTROMAGNET STARTER? WHAT EFFECT DO THE POLE SHOES HAVE? REVIEW….
Elizabethtown Technical CollegeBasic Electricity BEXS100/101Text: Delmar’s Standard Textbook of ElectricityMagnetic Motors