3B SCIENTIFIC PHYSICS 1017801 Instructions D'utilisation page 5

3B SCIENTIFIC ® PHYSICS
Electromotor and Generator, Complete 1017801
Instruction manual
01/14 TL/ALF
1. Safety instructions
The magnet is not attached to the base plate but
remains loose, so there is a risk of it falling.
Caution: Certain unauthorised operating condi-
tions (excess voltage, supply of current when
stationary) could cause the armature winding to
get hot.
• Stay within the permitted operating parame-
ters.
2. Description
The equipment is a working model to demonstrate
the basic operating principle of electric motors and
generators. The simple and easily understood de-
sign closely mirrors the fundamental principle. The
commutator, slip rings for AC operation and the
armature coil are all located on the armature shaft.
The commutator and current collectors change
the polarity of the armature coil after each half
turn of the armature shaft. As the armature coil
passes through a vertical position aligned along
the magnetic field, the polarity of the coil changes
in such a way that its north pole N is adjacent to
the north pole of the magnet and its south pole is
opposite the magnet's south. The momentum of
the coil causes it to move past this point and the
repulsive force of the like poles then exert a
torque on the coil. Once the armature coil moves
past the horizontal position, attractive forces be-
tween the magnet and the rotor then become
increasingly dominant.
When set up as a DC generator, the model out-
puts a sinusoidal half-wave signal (pulsating DC).
The polarity depends on the position of the mag-
net and the direction of rotation.
When set up as an AC generator (current collec-
tors reconnected on to the slip ring), it is possible
to obtain an output close to a sinusoidal voltage.
1
1 Magnet
2 Armature shaft
3 Left-hand bearing
support
4 Armature coil
5 Slip ring
6 Commutator
7 Attachment for current
collectors (left: AC,
right: DC)
8 Current collectors
9 Right-hand bearing
support
10 Connector sockets for
current collectors
11 Drive pulley / hand
crank
12 Leaf springs for cur-
rent collectors
13 Carbon brushes