🔍 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.