1. What is Motor Sizing?

Motor sizing is the process of determining the appropriate power rating for an electric motor based on the mechanical load requirements, efficiency, and safety factors to ensure reliable operation.

2. How Does the Calculator Work?

The calculator uses the motor power equation:

Where:

• \( P \) — Required motor power (kW)
• \( Load \) — Mechanical power required by the application (kW)
• \( \eta \) — Efficiency of the motor and drive system (0-1)
• \( Safety\ Factor \) — Design margin (typically 1.1-1.5)

Explanation: The equation accounts for power losses through efficiency and adds a safety margin to prevent motor overload.

3. Importance of Proper Motor Sizing

Details: Correct motor sizing ensures energy efficiency, prevents premature failure, and maintains system reliability. Oversized motors waste energy while undersized motors may overheat.

4. Using the Calculator

Tips: Enter the mechanical load power in kW, estimate the system efficiency (default 0.85), and select an appropriate safety factor (default 1.15). All values must be valid (load > 0, 0 < efficiency ≤ 1, safety factor ≥ 1).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical efficiency value for electric motors?
A: Standard efficiency motors range 0.75-0.90, while premium efficiency motors can reach 0.92-0.96.

Q2: How do I determine the safety factor?
A: Consider 1.1-1.2 for stable loads, 1.3-1.5 for variable or uncertain loads, and higher for harsh conditions.

Q3: Should I round up to standard motor sizes?
A: Yes, after calculation, select the next standard motor size (e.g., 5.5 kW, 7.5 kW, 11 kW, etc.).

Q4: What other factors should be considered?
A: Duty cycle, ambient temperature, altitude, starting torque requirements, and power supply characteristics.

Q5: How does voltage affect motor sizing?
A: Voltage determines current draw but not power rating. Ensure the selected motor matches your supply voltage.