(a) hold the armature stampings in position
(b) ventilate the armature
(c) protect the whole machine
(d) provide return path for the flux
Answer:(a) hold the armature stampings in position.
Explanation:
CONCEPT
- The stator is the stationary part of an induction motor.
- It carries the stator core and three-phase windings.
- These parts must be held firmly and accurately aligned with the rotor.
- The stator frame is the outer structure that provides this mechanical support.
FUNCTION OF STATOR FRAME
- The stator frame holds the stator core, stampings, and windings in position.
- It maintains proper alignment between stator and rotor.
- It ensures a uniform and small air gap.
- It prevents displacement of windings during operation.
- It provides rigidity and mechanical strength to the machine.
Thus, its primary function is:
👉 Structural support of stator core and windings
IMPORTANCE OF PROPER SUPPORT
- The air gap in an induction motor is very small.
- If the frame is weak:
- Rotor becomes eccentric
- Unbalanced magnetic pull occurs
- Vibration and noise increase
- Efficiency reduces
- Therefore, a strong frame is essential.
WHY OTHER OPTIONS ARE INCORRECT
(b) Ventilate the Armature ❌
- Ventilation is done by:
- Cooling fan
- Air ducts
- Ventilation passages
- The frame does not directly perform ventilation.
(c) Protect the Whole Machine ❌
- The frame provides outer protection.
- But protection is only a secondary function.
- The main engineering purpose is mechanical support.
(d) Provide Return Path for Flux ❌
- Magnetic flux flows through:
- Stator core
- Rotor core
- Air gap
- These parts are made of silicon steel laminations.
- The frame material is not designed for magnetic flux.
FINAL CONCLUSION ⭐
The stator frame of an induction motor mainly provides mechanical support to the stator core and windings and maintains correct alignment with the rotor. This ensures proper air gap and smooth operation. Hence, its primary function is structural support.
CORRECT ANSWER
✅ hold the armature stampings in position.
KEY ONE-LINE EXAM STATEMENT ⭐
The main function of the stator frame is to support and rigidly hold the stator core and windings in correct alignment with the rotor.