Electric Meters & Motors

Demos to Prepare:

Meter Movement Demonstrator.
Various meters.
The Big Magnet.
Roach clips.
Coils and bar magnets.
Generator demo.
Motor demo.
Japanese motor-generators.
Selsen motor.
Synchronous motor.
Boom's Motors and Generators.

The Hot Wire Ammeter for Alternating Current

Thumb points in the direction of the thrust, forefinger points in the
direction of the
flux (N to S), and the center finger points in the
direction of the
current flow (- to +).

The Armature and Stator concentrate the magnetic flux fields.

Slip Rings remove AC from the spinning armature.
The current is alternating because the direction of motion
changes each half turn. (See LH generator rule above).

To change the AC in the rotating armature to DC, a split-ring
commutator is used. It switches the wires each half turn so that
the same polarity is maintained upon each brush.

The Commutator in action changing the AC in the rotor into DC. Video:

Naval Generator (dynamo).

The 50 Capper

A Rack and Pinion gear spins up a generator that
will ignite 50 dynamite caps!

Alternating Current is produced in every armature:

The Reference Circle Generation Video:

Three Phase Generators and Motors have three
sets of coils that cut the magnetic lines to give
three sine waves separated by 120o.

This greatly increases the efficiency.

The Commutator in a motor reverses the direction of the current each half turn so that the armature will continue to rotate. Video:

Naval Motor

An induction motor uses AC to keep the
magnetic field cutting through the rotor coils.
This induces a current in the rotor without
the need of brushes and commutator.

Great Three-Phase Generators at Niagra. Video:

Three Phase Systems are Synchronized

Here Endeth Electric
Meters and Motors