1️⃣ The stator winding is connected to AC supply and the rotor winding is short-circuited
2️⃣ The rotor winding is connected to AC supply and the stator winding is short-circuited
3️⃣ Both stator and rotor windings are connected to AC supply
4️⃣ Stator winding is connected to AC supply and rotor winding to DC supply
✅ Answer (Detailed Solution Below)
✔️ Option 1: The stator winding is connected to AC supply and the rotor winding is short-circuited
📖 Detailed Solution
🔹 In an induction motor, the stator is the primary winding.
🔹 It is connected to a three-phase AC supply.
🔹 AC supply produces a rotating magnetic field.
🔹 This rotating field cuts rotor conductors.
🔹 EMF is induced in the rotor.
🔹 Rotor current flows due to short-circuited rotor.
🔹 Interaction of stator flux and rotor current produces torque.
🔹 Hence, the rotor acts as a short-circuited secondary winding.
👉 Therefore, stator is connected to AC and rotor is short-circuited.
⚙️ Transformer Analogy
| Part | Transformer | Induction Motor |
|---|---|---|
| Primary | Primary winding | Stator |
| Secondary | Secondary winding | Rotor |
| Supply | AC | AC (Stator) |
| Secondary | Shorted | Rotor shorted |
🔄 Stator and Rotor Connection
Stator
🔹 Slots carry three-phase windings.
🔹 Connected in star or delta.
🔹 Supplied with AC.
🔹 Produces RMF.
Rotor
🔹 Can be squirrel cage or wound type.
🔹 Generally star-connected (wound rotor).
🔹 May be star or delta depending on starting method.
🔹 Normally short-circuited.
❌ Why Other Options are Incorrect
(2) Rotor Connected to AC ❌
🔹 Rotor is never directly connected to supply.
(3) Both Connected to AC ❌
🔹 Only stator receives supply.
(4) Rotor Connected to DC ❌
🔹 DC cannot produce induction.
📌 Additional Information
⭐ Squirrel cage → Rotor shorted by end rings
⭐ Slip ring → Rotor shorted after starting
⭐ External resistance → Only during starting (wound rotor)
📌 Key Exam Notes
⭐ Supply → Given to stator
⭐ Rotor → Induced current
⭐ Working → Transformer principle
⭐ Connection → AC to stator
📝 Final Summary
📍 In an induction motor, AC supply is given to the stator, and the rotor remains short-circuited to allow induced current flow.
👉 Hence, Option 1 is Correct.