Includes Teacher's Notes and Typical Experiment Results Instruction Manual and Experiment Guide for the PASCO scientific Model SE-8658A 012-07210A 8/99 PERMANENT MAGNET MOTOR © 1999 PASCO scientific $5.00 better 10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA Phone (916) 786-3800 • FAX (916) 786-8905 • email: techsupp@PASCO.
The exclamation point within an equilateral triangle is intended to alert the user of important operating and safety instructions that will help prevent damage to the equipment or injury to the user.
012-07210 A Permanent Magnet Motor Table of Contents Section ...................................................................................................... Page Copyright and Warranty, Equipment Return ................................................. ii Introduction ..................................................................................................... 1 Equipment ....................................................................................................... 1 Table 1.
012-07210A Permanent Magnet Motor Copyright, Warranty, and Equipment Return Please—Feel free to duplicate this manual subject to the copyright restrictions below. Copyright Notice Equipment Return The PASCO scientific Permanent Magnet Motor manual (012-07210A) is copyrighted and all rights reserved. However, permission is granted to non-profit educational institutions for reproduction of any part of the manual providing the reproductions are used only for their laboratories and are not sold for profit.
012-07210A Permanent Magnet Motor Introduction The PASCO SE-8658A Permanent Magnet Motor operates on AC or DC current, and it can be used to generate alternating or direct current. key concepts and relationships concerning motors and electric current, using the Permanent Magnet Motor in conjunction with an AC or DC power supply and sensors for voltage, current, and rotational speed.
Permanent Magnet Motor 012-07210A ➤ NOTE: Although the instructions for experiments in this manual are for mechanical setups with specific PASCO equipment, the experiments in this manual may be set up in a variety of ways, depending upon the equipment you have available. They can all be done with or without the PASCO Science Workshop computer interface. Table 1 lists the equipment suggested for optional experimental setups.
012-07210A Permanent Magnet Motor Operation Options for electrical connections Starting the motor • Banana-style plugs may be inserted into openings in the base of 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. • Large alligator clips may be attached to the brass posts that hold the brushes.
Permanent Magnet Motor 012-07210A Initial Assembly Initial Assembly of Permanent Magnet Motor 2. Gently lower the armature onto the shaft. To make a DC motor, the split ring commutator should be down; for an AC motor, the dual slip-ring commutator should be down. Carefully rotate the armature back and forth to separate the brushes and allow the commutator to slip down between them. If necessary, insert a pencil or similar object down between the brushes.
012-07210A Permanent Magnet Motor Suggested Uses Operation as a DC motor Operation of a synchronous AC motor The Permanent Magnet Motor can be used to demonstrate the operation of a DC motor ( Experiment 1).
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012-07210A Permanent Magnet Motor Experiment 1: Operation of the DC Motor EQUIPMENT NEEDED: •Permanent Magnet Motor • low voltage DC power supply, limited to 1 A • multimeter • patch cords • small piece of masking tape Purpose The purpose of this experiment is to demonstrate the operation of the DC motor in terms of basic concepts of electromagnetism.
Permanent Magnet Motor • Grip the brass posts of the brush holder with large alligator clips; or • Attach small alligator clips to the ends of the brass strips that serve as brushes. 012-07210A PA S ME TE R CO sc ien tifi c MO PU S CU H F RR OR EN T DE LS F-9 58 4L OW VO LT AG EA C/D C 0- PO W 24 ER VO LT S DC DC OU TP Adjust the power source to deliver 6 volts of DC current limited to 1.0 amp. (Have your teacher show you how if you don’t know.
012-07210A Permanent Magnet Motor Draw arrows indicating the direction of current flow. N direction of wire wrapping on the coil Indicate whether north (N) or south (S). + When you wrap your fingers in the direction of the current flow in a coil, your thumb points towards the north pole of the magnetic field. + wire connected to the + terminal of the power supply Figure 1.
Permanent Magnet Motor 012-07210A 7. Turn the armature over 180° and imagine that the brush attached to the + lead is contacting the other split ring of the commutator. Note the path of the wire from where it is attached to the split ring to where it enters and exits from the coil on the right side of the armature. Imagine a current running through the wire and use the right-hand rule to determine the direction the magnetic field would flow.
012-07210A Permanent Magnet Motor Procedure—Part B 1. Turn on the power. Adjust the output voltage to 6 volts. 2. Use the small cylindrical ceramic magnet to check your predictions from steps 5 and 6 above. The painted face of the magnet is its North Pole (north-seeking pole). [You can verify this by hanging the magnet from a thread and observing that the painted face points toward the North (toward the earth’s north magnetic pole, located in northern Canada).
Permanent Magnet Motor 012-07210A 5. While the motor is running, raise the voltage to approximately 8 volts.
012-07210A Permanent Magnet Motor Experiment 2: Operation of AC and DC Generators EQUIPMENT NEEDED OPTIONAL EQUIPMENT • Permanent Magnet Motor • multimeter or galvanometer • patch cords • Voltage Sensor • computer interface • small strips of masking tape Purpose The purpose of this experiment is to detail the operation of an AC generator and a DC generator in terms of basic concepts of electromagnetism.
Permanent Magnet Motor 012-07210A Setup 1. Gently lower the armature onto the shaft with the dual slip-ring commutator pointed down. Carefully rotate the armature back and forth to separate the brushes and allow the commutator to slip down between them. If necessary, insert a pencil or similar object down between the brushes. Use only the most delicate force to avoid bending the brushes and necessitating adjustments or repairs. 2. Connect the motor to the meter by one of these methods (Figure 2.
012-07210A Permanent Magnet Motor 4. Label the end of the armature that connects to the upper slip ring with a small piece of tape. 5. Gently replace the armature onto the shaft. The dual slip-ring commutator should be down. Carefully rotating the armature back and forth will often separate the brushes and allow the commutator to slip down between them; otherwise, insert a pencil or similar object between the brushes to separate them.
Permanent Magnet Motor 012-07210A b) To oppose the motion during the second 90 degrees of rotation, which pole (N or S) would the taped end of the armature need to be? 9.
012-07210A Permanent Magnet Motor Part B: DC Generator 1. Review steps 1 and 5. Then remove the armature and install it with the split ring commutator down between the brushes. 2. Connect the meter and rotate the armature slowly, at a rate of about one complete revolution in two seconds.
Permanent Magnet Motor 012-07210A 4. If you have a PASCO computer interface and Voltage Sensor, try this: a) Predict how a graph of voltage versus time would look if you put the dual slip rings down and spun the armature rapidly and let it slow to a stop. b) What if the split rings were down? c) What if the split rings were down, but you spun it in the opposite direction? d) Test these predictions if the proper equipment is available.
012-07210A Permanent Magnet Motor Experiment 3: Operation of an AC Synchronous Motor EQUIPMENT NEEDED • Permanent Magnet Motor • patch cords • Digital Stroboscope or Digital Photogate Timer • multimeter • corrugated cardboard • power source that will deliver both DC and AC current limited to 1.0 A Purpose The purpose of this experiment is to demonstrate the operation of an AC synchronous motor in terms of basic concepts of electromagnetism.
Permanent Magnet Motor 012-07210A allow the commutator to slip down between them. If necessary, insert a pencil or similar object down between the brushes. Use only the most delicate force to avoid bending the brushes and necessitating adjustments or repairs. Procedure—Part A 1. Remove the armature from the shaft by grasping it between your thumb and forefinger and rotating it back and forth while lifting gently.
012-07210A Permanent Magnet Motor 7. Turn the armature over 180° and imagine that the AC current is in the positive half of the waveform. Note the path of the wire from where it is attached to the slip ring to where it enters and exits from the coil on the left side of the armature. Use the right-hand rule to determine the direction that the magnetic field would flow. Is the north pole on the same arm of the armature as in step 5? 8. Imagine that the AC current is in the negative half of the waveform.
Permanent Magnet Motor 012-07210A 3. Now set the power source to furnish to the brushes on alternating current with a sinusoidal waveform at a frequency of about 30 Hz and voltage of about 6 volts. Slowly rotate the armature by hand through one complete revolution. a) Describe the sensation you feel. b) Explain why this happens. 4. Repeat this with 30 Hz and 4 volts. a) Does this feel different? How? b) Explain why.
012-07210A Permanent Magnet Motor tape. Slip the square part far enough way down the split ring commutator so you can grip the plastic bushing to spin the armature. Position the photogate so the corners of the square interrupt the photogate’s beam 4 times per revolution. ➤ Notice that the motor is not self-starting.
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012-07210A Permanent Magnet Motor Teacher’s Guide Experiment 1: Remind students not to prolong situations when the armature is not spinning and the power is connected—the coils will overheat. Figure 1. 4, labeled Draw arrows indicating the direction of current flow. N Indicate which pole is north (N) or south (S).
012-07210A Permanent Magnet Motor Part B 3. Results of the test should agree with predictions. 4. Clockwise, if the leads are connected exactly as shown in Figure 2 and the north pole of the field magnets are on the left. 5. a) It should rotate in the counter-clockwise direction. b) Answers will vary.
012-07210A Permanent Magnet Motor Part B: DC Generator 1. a) The voltage and current produced is always in the same direction (direct current) but is pulsating, not steady. (The pulsating nature will be difficult to note with a digital meter.) Assuming as before that the negative lead of the meter is connected to the upper brush and the positive lead is connected to the lower brush, then if armature is rotated clockwise (as viewed from above) the meter will read positive.
012-07210A Permanent Magnet Motor 6. Opposite 7. Yes 8. a) The armature’s north pole alternates from end to end as the AC waveform alternates from positive to negative. b) The slip-ring commutator connects the armature to the power source by way of the brushes and enables the current to travel in an unbroken stream from the positive to the negative terminals of the power supply. Part B 3. a) The armature vibrates or pulses.
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