Shunt circuit motors (Item No.: P )

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Edward Barrett
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1 Teacher's/Lecturer's Sheet Shunt circuit motors (Item No.: P ) Curricular Relevance Area of Expertise: Physik Education Level: Klasse 7-10 Topic: Elektrizitätslehre Subtopic: Elektromotor und Generator Experiment: Der Nebenschlussmotor Difficulty Preparation Time Execution Time Recommended Group Size Intermediate 10 Minutes 10 Minutes 2 Students Additional Requirements: Experiment Variations: Keywords: Task and equipment Information for teachers Additional information When electric motors with a higher performance are required, they are generally constructed with electromagnets instead of permanent magnets, as above all these can generate stronger magnetic fields. In a shunt motor, the armature coil and the field coil are connected in parallel. The experiments are so designed, that they only provide qualitative or semi-quantitative results. Notes on setup and procedure An important prerequisite for the functioning of the motors is the correct connection of the two field coils (wound in the same direction) of the stator; as otherwise the magnetic fields generated by the current-carrying coils cancel each other out. Remarks Electromotors which can be driven by both direct and alternating current are called universal or AC/DC motors. Their coil cores are generally laminated. Shunt circuit motors have a lower initial torque than main circuit motors but they run more evenly when the load does not vary too much. They are therefore suitable to drive equipment which requires constant turning speeds, e.g. machine tools and lifts.

Shunt circuit motors (Item No.: P1376400) Task and equipment Task What are the characteristics of shunt circuit motors?

2 Shunt circuit motors (Item No.: P ) Task and equipment Task What are the characteristics of shunt circuit motors? Assemble a model of an electric motor in which the permanent magnet is replaced by an electromagnet, and -se it to examine which the characteristics of the motor are when the coil of the stator and the rotor are connected in parallel.

3 Equipment Position No. Material Order No. Quantity 1 Straight connector mod-le, SB Angled connector mod-le, SB Interr-pted connector mod-le, SB J-nction mod-le, SB On-off switch mod-le, SB Coil, 400 t-rns U-core Motor model for st-dent experiments Connecting cord, 32 A, 250 mm, red Connecting cord, 32 A, 250 mm, bl-e Connecting cord, 32 A, 500 mm, red Connecting cord, 32 A, 500 mm, bl-e PHYWE power s-pply DC: V, 2 A / AC: 6 V, 12 V, 5 A M-lti-range meter, analog-e

Set-up and procedure Set-up Set -p the motor model as

2; connect the ammeter directly to the power s-pply, so

4 Set-up and procedure Set-up Set -p the motor model as shown in Fig. 3; with the windings of the armat-re and the electromagnet connected in parallel. Set -p the circ-it as shown in Fig. 1 and Fig. 2; connect the ammeter directly to the power s-pply, so that s-fficient connecting cord is available; select the 3 A- meas-rement range. Fig. 1 Fig. 2 Fig. 3

5 Procedure Switch on the power s-pply and set it to 5 V. Set the armat-re at a slant; close the switch and give the armat-re a slight p-sh if req-ired; observe the t-rning direction. Reverse the polarity of the operating voltage of the motor by switching over contacts 1 and 2; observe the t-rning direction of the armat-re and compare it with the previo-s t-rning direction; note what yo- observe -nder Res-lt - Observations 1 in the report. Open the switch, reverse back contacts 1 and 2 and now reverse the polarity of the connections to the armat-re; close the switch; observe the t-rning direction and note what yo- observe -nder Res-lt - Observations 2. Vary the operating voltage between 4 V and 6 V and observe the speed of revol-tion of the motor while doing so, note yo-r observation -nder Res-lt - Observations 3. Set the operating voltage to 6 V- and p-t a load on the motor by braking the armat-re with finger press-re on the disc with the comm-tator; while doing this observe the speed of revol-tion and the ammeter display; note yo-r observations -nder Res-lt - Observations 4, open the switch. Connect the ammeter in the circ-it with the armat-re (to check the armat-re c-rrent), close the switch, p-t load on the motor; note yo-r observation -nder Res-lt - Observations 5. Now connect the ammeter in the branch of the circ-it with the two coils (to check the field c-rrent). Close the switch, again p-t load on the motor; observe the speed of revol-tion and the ammeter display; note yo-r observations -nder Res-lt - Observations 6. Open the switch, set 6 V alternating voltage and select the 3 A~ meas-rement range; close the switch and observe the motor; note yo-r observations -nder Res-lt - Observations 7. Switch off the power s-pply.

6 Report: Shunt circuit motors Result - Observations 1 (10 Punkte) Result - Observations 2 (10 Punkte)

7 Result - Observations 3 (10 Punkte) Result - Observations 4 (10 Punkte)

8 Result - Observations 5 (10 Punkte) Result - Observations 6 (10 Punkte)

9 Result - Observations 7 (10 Punkte) Evaluation - Question 1 (10 Punkte) Why can a shunt circuit motor be driven by direct current as well as by alternating current?

10 Evaluation - Question 2 (10 Punkte) How can one change the direction of rotation? Evaluation - Question 3 (10 Punkte) How do the intensity of the field current (the intensity of the current in the coils of the electromagnet) and the intensity of the armature current change under load?

11 Evaluation - Question 4 (10 Punkte) What is to be expected of the turning direction, when the polarity of the field coils is reversed instead of that of the armature?

Sulphurous acid - environmental hazards due to the combustion of fossil fuels (Item No.: P )

Teacher's/Lecturer's Sheet Sulphurous acid - environmental hazards due to the combustion of fossil fuels (Item No.: P7158000) Curricular Relevance Area of Expertise: Chemie Education Level: Klasse 7-10