13/04/2026
Shaded-Pole Motors: Pros and Cons
Shaded-pole motors are one of the simplest and most inexpensive types of single-phase AC motors. They are commonly found in small appliances like fans, microwave ovens, and refrigerator defrosters. Below is a brief look at their key benefits and drawbacks.
Advantages
Low Cost – Their simple construction (no capacitor, centrifugal switch, or complex windings) makes them very cheap to manufacture.
High Reliability – With few parts, there is little that can break or wear out, leading to long service life.
Low Maintenance – No brushes or switches to replace. Operation is silent (no clicks or sparking).
Simple Starting – They are self-starting and require no extra starting circuitry.
Disadvantages
Poor Efficiency – Efficiency is typically only 5–35%. A large amount of energy is lost as heat, making them uneconomical for continuous operation.
Low Starting Torque – About 30–50% of rated torque. They cannot start under heavy loads.
Low Power Factor – Usually 0.4 to 0.6 lagging, which is poor compared to other motor types.
Speed Regulation – Speed drops significantly with load; speed control is not precise.
Limited Power Range – Practically used only for fractional horsepower applications (typically under 50 watts).
