How is the speed of a synchronous motor...

Question 1 / 270705eccefa4bacbc34ba4d48232

Question 1 of 270705eccefa4bacbc34ba4d48232

How is the speed of a synchronous motor varied?

Question 1 of 27070

How is the speed of a synchronous motor varied?

🔍 Key Concepts

• Synchronous speed formula for AC motors (relationship between speed, frequency, and number of poles) • Difference between synchronous motors and induction motors in how speed is controlled • Effect of voltage and field excitation on torque and power factor vs on speed

💭 Think About

• Which quantity directly appears in the formula for synchronous speed, and which quantities only affect torque or power factor? • Think about what happens to the rotating magnetic field in the stator when each option is changed—does its speed actually change? • For a synchronous motor running at no slip, what must change in the supply for the shaft speed to change?

✅ Before You Answer

• Write or recall the formula for synchronous speed in revolutions per minute (rpm). Identify which variable in that formula you can adjust in a real power system. • Consider whether swapping line leads changes direction or speed of rotation. • Consider whether field excitation changes rotor electrical characteristics (power factor, torque) or the actual mechanical speed.

Question 1 of 27070

How is the speed of a synchronous motor varied?

interchanging any two of the three live leads

changing the voltage of the system

changing the input frequency

increasing the field excitation