Ac Motors

AC Motors

Several advantages
Many types, no brushes, or commutators, or sparks
Well suited, constant-speed
Some, variable speed
Varying phases, cheaper

Aircraft electrical systems
Typically, 400 Hz AC
Seven times speed of a 60 Hz aim, same pole count
6,000 to 24,000 rpm
Gearing can create torque

Types of AC motor
Universal motor
Induction motors (several)
Synchronous motor

Universal motors
Fractional AC series motors
Operate on either AC or DC
Brushes, commutator
Fans, portable tools

Induction motor overview
Most popular AC motor
No connections between
1. motor housing
2. rotating element
No brushes, commutator, slip rings
Fixed rpm, depending on
1. motor design
2. frequency of AC
Single-or three-phase AC

Single phase induction
Lower power requirements
Requires startle circuit
Starter must disconnect once motor is running
Reversible, by start circuit

Three- phase induction
Self-starting
High power requirement
Starters, flaps, landing gear, hydraulic pumps

Induction motor construction
Two primary parts
1. stator
2.



rotor

Stator construction
? Windings in slot
? Around stator periphery
? Series of electromagnetic

rotor coil construction
? Iron core
? make out circular laminations
? Soft steel, keyed in shaft
? Longitudinal slot, sinister copper or aluminum bars

Stator windings contract
? Revolving magnetic field
? voltage induced in bars
1. current flows in bars
2. adds magnetic field
? Rotor rotation nearly synchronous, stator field
? Slight difference needed
1. produce torque
2. produce rotation
? Difference= motor slip

Single-phase induction motor
? solitary(prenominal) one stator winding
? Field pulsates
? Expanding, collapsing field induces current...If you want to buy off a full essay, order it on our website: Orderessay



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