In electric machine applications, which is the most commonly used type of AC motor for industrial and commercial drives?

Introduction / Context:
AC motors drive the majority of pumps, fans, compressors, and conveyors worldwide. Selecting the most common type highlights practical engineering awareness, cost/complexity trade-offs, and grid compatibility. This is a conceptual recall question grounded in industrial practice.

Given Data / Assumptions:

• Standard power systems and typical facility infrastructure.
• Focus on prevalence, robustness, and efficiency.

Concept / Approach:
Three-phase induction motors dominate due to their self-starting capability (with proper design), high efficiency, simple construction (no brushes), ruggedness, low maintenance, and the widespread availability of three-phase power in industrial settings. Their torque characteristics suit many loads, and variable-frequency drives further extend performance and control.

Step-by-Step Reasoning:

Verification / Alternative check:
Industry catalogs and standards strongly feature three-phase induction machines across a wide power range. VFD proliferation reinforces this dominance by enabling efficient speed control.

Why Other Options Are Wrong:

• Single-phase induction: common for small appliances, not most common across industrial/commercial scale.
• Two-phase induction / two-phase squirrel-cage: Two-phase systems are rare historically; modern grids are three-phase.

Common Pitfalls:

• Generalizing household prevalence to industrial usage.

Final Answer:
three-phase induction motor