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GENERATORS

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									Generators: 1. AC Generator (single phase, domestic):  Veff = 0.707 Vmax  label the following: slip rings (1), carbon brushes (2), stator (field coil) (3), and rotor (output coil) (4)  identify the armature (5)  draw the AC waveform
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2. AC Generator (three phase, industrial):
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 label the following: slip rings (1), carbon brushes (2), stator (stationary output coils) (3), and rotor (rotating field coil) (4)  identify the armature (5)  draw the AC waveform

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3. DC Generator (old automobile generators)  label the following: split ring commutator (1), carbon brushes (2), stator (field coil) (3), and rotor (output coil) (4) N S  identify the armature (5)  draw the waveform.

Electric Motors 1. Universal Motors (AC or DC)  provide high torque,,  brushes wear, need maintenance, not for continuous service  good for small appliances (power tools, vacuum cleaners, food mixers, etc.)  label carbon brushes, commutator, stator (field coil), and rotor 1. 4.  identify the armature 2.
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2. AC Induction Motors (single phase residential or 3-phase industrial)  rotor has no applied voltage - only an induced voltage which follows the moving magnetic field of the stator windings.  these have no brushes and so are low maintenance and can be used for continuous service, e.g., fan motors  the rotor in a 3-phase induction motor spins when induced by 3 separate AC currents in the stator coils which are 120  out of phase.  a single phase AC current will also power an induction motor since each of the stator V windings are slightly offset, creating a timevarying magnetic field which the rotor follows.  single phase induction motors need an extra circuit for increased torque for starting, i.e., they have a capacitor in parallel with the motor which causes the current to lead the applied voltage in the stator, which causes the induced voltage in the rotor to be out of phase (ahead of) the voltage in the stator.  once they reach high speed, a centrifugal switch disconnects the capacitor circuit.  label the stator (field coil) and rotor, and identify the armature. Note that the armature is always the coil where power output occurs, i.e., either electric power output in the case of generators or mechanical power output for motors.


								
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