As shown in the illustrated wound-rotor...

🔍 Key Concepts

• Wound-rotor induction motor speed control – how changing rotor circuit resistance affects slip and running speed. • Rotor resistor connection shown in EL-0148 – carefully note whether the external rotor resistors are connected in wye or delta in the illustration and small schematic. • Relationship between increased rotor resistance, torque, and speed at a given load.

💭 Think About

• When you add more resistance into the rotor circuit of a wound-rotor induction motor, what happens to slip and does the rotor speed move closer to or farther from synchronous speed? • Look closely at the small rheostat diagram: when the handle is moved toward the side marked "Increase Speed," is resistance being added or removed from the rotor circuit? • From the labels on the resistor bank in the illustration, which connection (wye or delta) is actually used for the external rotor resistors in this motor?

✅ Before You Answer

• Verify from the illustration labels whether the external rotor resistor bank is drawn and tagged as wye or delta connected. • Confirm from your motor theory that higher rotor resistance at constant load means higher slip (lower speed) and lower resistance means lower slip (higher speed). • Match the choice that both (1) names the correct connection (wye or delta) as shown, and (2) states the correct direction of resistance change for increasing speed.

As shown in the illustrated wound-rotor induction motor, what statement is true concerning changing the motor speed? See illustration EL-0148.

To increase speed, the resistance of the external delta-connected rotor resistor bank must be decreased.

To increase speed, the resistance of the external delta-connected rotor resistor bank must be increased.

To increase speed, the resistance of the external wye-connected rotor resistor bank must be decreased.

To increase speed, the resistance of the external wye-connected rotor resistor bank must be increased.

🔍 Key Concepts

💭 Think About

✅ Before You Answer