PASCO SE-8658A PERMANENT MAGNET MOTOR - Manual (Page 7)

3
012-07210A Permanent Magnet Motor
Starting the motor
• The motor is not self-starting. Immediately after
you apply the power, start the motor manually by
grasping the black plastic bushing at the top of the
armature assembly between your thumb and
forefinger and spinning the armature.
• With the Permanent Magnet Motor configured as
either a DC or universal motor, almost any
attempt you make at spinning the armature will
result in successfully starting the motor; only the
direction of the spin is important.
• When configured in an AC synchronous mode,
the motor must be spun at a speed that
approximately matches the frequency of the
power source. This is impractical at frequencies
much above 30 Hz, and some students may
require assistance even a lower frequencies.
Maintenance and Storage
• The motor may be stored in the plastic bag
furnished; this will keep it dust free and reduce
problems of corrosion that may occur in areas
having high humidity.
• The commutators and brushes will experience
wear, oxidation, and pitting and will require
attention from time to time. Rotate the armature
slowly by hand and monitor current flow or
sense the force developed to determine whether
proper contact is occurring between brushes and
commutator. To restore proper operation, clean
the contacts with emery paper or shift the
brushes somewhat to expose new surfaces.
• Careless installation of the armature onto the
shaft might bend the brushes. You can easily
bend them back into their original shape with
finger pressure.
Operation
Options for electrical connections
• Banana-style plugs may be inserted into openings in
the base of the motor.
• Large alligator clips may be attached to the brass
posts that hold the brushes.
• Small alligator clips may be attached directly to the
ends of the brushes where they protrude from the
slits in the brass posts.
Power Sources Warnings
It is important to limit the current of the
power source to 1.0 A to avoid damaging
the coils of the armature. This may be
done by:
• Choosing a power supply that may be
set to limit the current to a maximum
value of 1.0 (See Table 1 for specific
suggestions for power sources);
• Using a PASCO CI-6552A Power
Amplifier, which automatically limits
current to 1.0 A;
• Carefully monitoring current with:
- The power supply’s built-in current
meter, or
- Science Workshop and the CI-6556
Current Sensor, or
- A voltmeter or multimeter, by
measuring the voltage drop across a
low-value series resistor (such as 0.51
ohm, 1 watt), and calculating the
current.
For power supplies that do not have the
capability to measure output voltage, use
a multimeter or voltmeter to insure that
the current does not exceed 1.0 A. (See
Table 1 for specific suggestions for power
sources.)
➤ NOTE: If you are using a PASCO
CI-6502A Power Amplifier with a
CI-6500 Interface System, the distorted
waveform light will turn on during
operation of the motor, but no damage is
being done to the Power Amplifier; you
can ignore the light.