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In single-phase induction motor ┬╖ What is the efficiency for the output watt of 750?
0.38
0.48
0.65
0.69
0.69
The efficiency of a single-phase induction motor is defined as the ratio of mechanical output power to the electrical input power ┬╖ For a fractional horsepower motor with an output of 750 Watts, an efficiency of approximately 0.69 (69%) is a standard industrial benchmark reflecting typical losses like copper, iron, friction, and windage.
The efficiency of a single-phase induction motor is defined as the ratio of mechanical output power to the electrical input power ┬╖ For a fractional horsepower motor with an output of 750 Watts, an efficiency of approximately 0.69 (69%) is a standard industrial benchmark reflecting typical losses like copper, iron, friction, and windage.
╬╖=PinтАЛPoutтАЛтАЛ├Ч100 тАФ Percentage Efficiency
PinтАЛ=PoutтАЛ+PlossesтАЛ тАФ Power balance equation
The motor converts electrical energy into mechanical work through electromagnetic induction ┬╖ Losses such as I2R (copper) losses in windings, hysteresis and eddy current (core) losses, and mechanical friction limit the efficiency ┬╖ Since efficiency ╬╖=PoutтАЛ+╬гLossesPoutтАЛтАЛ, lower output ratings generally result in lower efficiency values compared to large three-phase machines.
Single-phase induction motors have lower efficiencies than 3-phase motors of similar capacity.
Efficiency increases with motor size up to a specific optimal load factor.
Input power always includes electrical, magnetic, and mechanical losses.
750 Watts is equivalent to approximately 1 Horsepower (HP).
Self-starting capability (with aux winding)
Simple and rugged construction
Low maintenance cost
Lower power factor compared to 3-phase machines
High starting current
Higher vibration levels due to pulsating magnetic fields
Domestic appliances like fans and mixers
Small centrifugal pumps and compressors
Typical efficiency range for small 0.75kW motors is 65% to 75%.
Option A (0.38) and B (0.48) represent extremely poor performance indicative of faulty or severely overloaded motors.
D is correct тАФ An efficiency of 0.69 represents a standard operating performance level for a typical 750W single-phase induction motor.
Always verify if the motor load matches the rated output; efficiency values drop significantly if the motor operates at a small fraction of its rated capacity.