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Refer to FIGURE 4.1 below and answer the questions that follow - NSC Electrical Technology Power Systems - Question 4 - 2017 - Paper 1
Question 4
Refer to FIGURE 4.1 below and answer the questions that follow. 4.1.1 Name any TWO parts of the motor in FIGURE 4.1. 4.1.2 Explain how the direction of rotation of... show full transcript
Worked Solution & Example Answer:Refer to FIGURE 4.1 below and answer the questions that follow - NSC Electrical Technology Power Systems - Question 4 - 2017 - Paper 1
Step 1
4.1.1 Name any TWO parts of the motor in FIGURE 4.1.
Answer
Two parts of the motor in FIGURE 4.1 include:
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Squirrel Cage Rotor: This part consists of conductive bars shorted at both ends and typically made of aluminum or copper. It allows the motor to create a magnetic field and is essential for torque production.
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Windings: These are coils of wire through which current flows to create the magnetic field, enabling the motor to start and run efficiently.
Step 2
4.1.2 Explain how the direction of rotation of this motor may be reversed.
Answer
The direction of rotation of a three-phase induction motor can be reversed by swapping any two of the three supply phases. When two phases are interchanged, the phase sequence changes, which in turn changes the direction of the magnetic field produced, leading to a reversal in the motor's rotation.
Step 3
4.1.3 Explain which connection would develop the greatest torque.
Answer
The delta connection will develop greater torque than the star connection. In a delta configuration, each winding receives the full supply voltage, resulting in a higher current flow. This increased current generates stronger magnetic fields, which leads to more torque being produced. Conversely, the star connection limits the phase voltage to approximately 0.577 times the line voltage, which results in lower torque production.
Step 4
4.2 State ONE advantage of a three-phase induction motor over a single-phase induction motor.
Answer
One advantage of a three-phase induction motor is that it requires less maintenance compared to a single-phase induction motor. This is primarily due to its design, which allows for smoother operation and better efficiency, thus reducing wear and tear on components.