1. What is Motor Service Factor?

The Service Factor (SF) of an electric motor is a measure of its overload capacity. It indicates how much a motor can be overloaded without causing damage or significant reduction in motor life.

2. How Service Factor is Calculated

The calculator uses the service factor formula:

Where:

• Rated Power — The maximum power the motor can deliver continuously at rated voltage and frequency
• Nominal Power — The standard power rating of the motor

Explanation: A service factor of 1.15 means the motor can handle 15% more load than its nominal rating for short periods without overheating.

3. Importance of Service Factor

Details: Service factor is crucial for motor selection, ensuring the motor can handle temporary overloads, voltage fluctuations, or other abnormal operating conditions without damage.

4. Using the Calculator

Tips: Enter both power values in the same units (kW or HP). Typical service factors range from 1.0 to 1.25 for most industrial motors.

5. Frequently Asked Questions (FAQ)

Q1: What is a good service factor for a motor?
A: Most standard motors have a service factor of 1.15. Higher service factors (1.25-1.35) are used for demanding applications.

Q2: Can a motor run continuously at its service factor load?
A: No, service factor is for temporary overload conditions only. Continuous operation at service factor load will reduce motor life.

Q3: Does service factor affect efficiency?
A: Yes, motors operating at service factor load typically have reduced efficiency and higher operating temperatures.

Q4: How does service factor relate to motor insulation class?
A: Higher insulation classes (B, F, H) allow for higher service factors by withstanding greater temperature rises.

Q5: Should I select a motor based on service factor?
A: Base selection on nominal power requirements first, then consider service factor for overload capacity if needed.