1. What is DC Motor Efficiency?

Motor efficiency (η) is the ratio of mechanical power output to electrical power input, expressed as a percentage. It measures how effectively a motor converts electrical energy into mechanical energy.

2. How Does the Calculator Work?

The calculator uses the efficiency formula:

Where:

• \( P_{out} \) — Mechanical output power (watts)
• \( P_{in} \) — Electrical input power (watts)
• \( \eta \) — Efficiency (percentage)

Explanation: The formula compares the useful power output to the total power consumed, with 100% representing perfect conversion (unattainable in practice).

3. Importance of Efficiency Calculation

Details: Efficiency calculations help evaluate motor performance, estimate energy costs, and compare different motor designs or brands.

4. Using the Calculator

Tips: Enter both power values in watts. Output power cannot exceed input power (would violate energy conservation). Typical DC motor efficiencies range from 70-90%.

5. Frequently Asked Questions (FAQ)

Q1: What's a good efficiency for DC motors?
A: Small DC motors typically achieve 70-85%, while large industrial motors may reach 90-95% efficiency.

Q2: How can I measure input/output power?
A: Input power = voltage × current. Output power = torque × angular velocity (or use a dynamometer).

Q3: Why is efficiency less than 100%?
A: Losses occur due to friction, windage, electrical resistance (I²R losses), and magnetic losses.

Q4: Does efficiency change with load?
A: Yes, motors typically peak in efficiency at 70-80% of rated load, dropping at both lighter and heavier loads.

Q5: How does temperature affect efficiency?
A: Higher temperatures generally decrease efficiency due to increased resistance and bearing friction.