Understanding Non-Self Starting Motors
In electrical engineering, it's crucial to identify the characteristics of different motors. Among them, the synchronous motor stands out as a non-self starting motor.

Why is the Synchronous Motor Non-Self Starting?
- **Operating Principle:**
- A synchronous motor operates at synchronous speed, which means it requires an external force to bring it to this speed initially.
- **Rotor Design:**
- The rotor of a synchronous motor is typically designed with either permanent magnets or is wound to produce a magnetic field. It cannot develop torque at standstill, which is essential for starting.
- **Starting Mechanism:**
- To initiate motion, synchronous motors often require an auxiliary starting mechanism, such as:
- A separate starting motor
- A variable frequency drive (VFD)
- **Torque Production:**
- Unlike induction motors that generate starting torque due to slip, synchronous motors need to reach synchronous speed before providing torque, making them reliant on external means for startup.

Comparison with Other Motors
- **D.C. Series Motor:**
- This motor develops high starting torque and can start under load conditions.
- **Squirrel Cage Induction Motor:**
- It is self-starting due to the slip between the rotor and stator magnetic fields.
- **Wound Rotor Induction Motor:**
- Also self-starting, it can provide variable speed and torque.

Conclusion
In summary, the synchronous motor's dependence on external forces for initial movement categorizes it as a non-self starting motor, making it distinct from other motor types that can start independently. Understanding these characteristics is vital for selecting the appropriate motor for various applications.