In continuous-duty applications, motors rated above how many horsepower must be protected against overload?

In continuous-duty applications, motors rated above how many horsepower must be protected against overload?

• A. 2
• B. 3
• C. 1/2
• D. 1

Answer: (D)

In continuous-duty operation, heat builds up in a motor because it runs for long periods, often at near-full load. To guard against damage from overheating, motors that are rated above 1 horsepower must have overload protection. This protection—typically a thermal overload relay in the motor starter or built into the motor—trips to disconnect power if current and heat exceed safe limits, preventing insulation damage and winding failure over extended running times. So the threshold for requiring overload protection in continuous duty is motors rated more than 1 horsepower.

In continuous-duty operation, heat builds up in a motor because it runs for long periods, often at near-full load. To guard against damage from overheating, motors that are rated above 1 horsepower must have overload protection. This protection—typically a thermal overload relay in the motor starter or built into the motor—trips to disconnect power if current and heat exceed safe limits, preventing insulation damage and winding failure over extended running times. So the threshold for requiring overload protection in continuous duty is motors rated more than 1 horsepower.