What temperature rise is specified for the 75-horsepower motor example?

What temperature rise is specified for the 75-horsepower motor example?

• A. 30°C
• B. 40°C
• C. 50°C
• D. 60°C

Answer: (B)

Temperature rise is how much the winding temperature is allowed to increase above the surrounding ambient temperature when the motor runs at its rated load. In the 75-horsepower motor example, the specified rise is 40°C, so the windings may run up to 40°C hotter than the ambient temperature during full-load operation. This value reflects the insulation class and cooling design used in the example, ensuring the winding temperature stays within safe limits while still achieving the required performance. For instance, if the ambient is around 25°C, a 40°C rise would bring winding temperature to about 65°C, which is well within typical insulation temperature ceilings. The other options don’t match the data given for this particular example.

Temperature rise is how much the winding temperature is allowed to increase above the surrounding ambient temperature when the motor runs at its rated load. In the 75-horsepower motor example, the specified rise is 40°C, so the windings may run up to 40°C hotter than the ambient temperature during full-load operation. This value reflects the insulation class and cooling design used in the example, ensuring the winding temperature stays within safe limits while still achieving the required performance. For instance, if the ambient is around 25°C, a 40°C rise would bring winding temperature to about 65°C, which is well within typical insulation temperature ceilings. The other options don’t match the data given for this particular example.