PASCO SE-8657 MOTOR ACCESSORY - Manual (Page 10)

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Motor Accessory 012-06247A
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Operation as a DC motor
The Motor Accessory can be used with the Variable
Gap Magnet to demonstrate the operation of a DC
motor ( Experiment 1). Students can explore relation-
ships between motor speed and voltage, as well as
between direction of armature rotation and polarity,
developing key concepts including: action of the split
ring commutator, dependence of speed on voltage,
dependence of direction of rotation on polarity, right-
hand rule, and direction of current flow from positive
to negative poles.
Action of AC and DC generators
Spinning the armature by hand while it is connected to
a sensitive DC meter or to the Signal Interface II
shows the action of an AC generator, as well as the
rectifying action of the commutator in a DC generator
(Experiment 2).
Operation of a synchronous AC motor
Coupled with an AC signal supplied by the PASCO PI-
9587C Digital Function Generator/Amplifier or similar
function generator, the Motor Accessory-Variable Gap
Magnet assemblies will operate in sync with 15 and 30
Hz (and often wider range) signals (Experiment 3).
Students can explore the relationship between AC
voltage and motor speed, as well as between AC current
frequency and motor speed. They can conduct detailed
explorations of the precision of synchronism of AC
current and motor speed with a PASCO SF-9211
Digital Stroboscope or PASCO ME-9215A Digital
Photogate or by observing the stroboscopic effect of an
ordinary fluorescent lamp at selected motor speeds. As
a result, they develop key concepts, including the
independence of AC motor speed and voltage, depen-
dence of AC motor speed on current frequency, and
action of a dual slip-ring commutator.
Suggested Uses
Operation as a universal motor
The Motor Accessory-Coils and Cores assembly
functions as a universal motor, operating on both AC
and DC power supplies (Experiment 4). Students can
explore the relationships of current direction and direc-
tion of the magnetic field, the effect of changes in
voltage and AC current frequency on motor speed, and
the effect of changes in DC voltage on motor speed.
Additional possibilities
The Motor Accessory–Variable Gap Magnet assembly
can be used to determine the speeds of maximum power
and maximum efficiency of a DC motor by varying the
load while simultaneously measuring the speed, torque,
and armature current. In this experiment, you can
measure the motor’s speed with a photogate or strobo-
scope.
The Motor Accessory–Coils and Cores assembly also
can be used to demonstrate series-wound, shunt-wound,
and hysteresis-synchronous motor setups.