📘 Synchronous Motor – Starting Methods
Synchronous motor is not self-starting. Special methods are used to bring rotor near synchronous speed.
🔹 1️⃣ Why Not Self Starting?
At starting:- Rotor is stationary
- Stator magnetic field rotating
🔹 2️⃣ Damper Winding (Most Common Method)
Also called: Amortisseur winding. Construction: Bars embedded in rotor pole faces (similar to squirrel cage). Working: 1. Motor starts like induction motor. 2. Rotor accelerates close to synchronous speed. 3. DC excitation applied. 4. Rotor locks with stator field. Very widely used method.🔹 3️⃣ Pony Motor Method
External small motor used to bring rotor to synchronous speed. Once speed reached: DC excitation applied → Rotor locks. Used in large machines.🔹 4️⃣ Slip Ring Induction Motor Starting
Some synchronous motors use external resistance in rotor for controlled starting. Less common today.🔹 5️⃣ Important Observations
- Damper winding makes motor self-starting
- After synchronism → No induced current in damper bars
- Synchronous motor runs exactly at synchronous speed
- No slip during steady state
🔹 Example Concept Question
Why does damper winding not affect normal operation? Because at synchronous speed: Relative speed = 0 No induced current → No effect.🎯 GATE Important Points
- Damper winding = Most common method
- Synchronous motor not self-starting
- No slip during normal operation
- Pony motor used for large machines
Damper Winding Makes Synchronous Motor Practically Usable
.png)
No comments:
Post a Comment