1. What are Motor Power and Torque Formulas?

Definition: These formulas calculate electrical power input and mechanical torque output of electric motors.

Purpose: Essential for motor selection, performance analysis, and system design in electrical and mechanical engineering.

2. How Do the Formulas Work?

The calculator uses two main formulas:

Where:

• \( P_w \) — Electrical power input (watts)
• \( V \) — Voltage (volts)
• \( I \) — Current (amps)
• \( \eta \) — Motor efficiency (0-1)
• \( PF \) — Power factor (0-1)
• \( T \) — Torque (lb-ft)
• \( HP \) — Horsepower
• \( RPM \) — Revolutions per minute

Explanation: The first formula calculates input power considering efficiency and power factor. The second relates mechanical power (HP) to torque at a given speed.

3. Importance of Motor Calculations

Details: Proper motor calculations ensure correct sizing, energy efficiency, and prevent overload conditions in electrical systems.

4. Using the Calculator

Tips:

• For power calculation: Enter voltage, current, efficiency (default 0.9), and power factor (default 0.85)
• For torque calculation: Enter horsepower and RPM
• All values must be positive numbers

5. Frequently Asked Questions (FAQ)

Q1: What is power factor?
A: Power factor is the ratio of real power to apparent power, typically 0.8-0.95 for motors.

Q2: Why 5252 in the torque formula?
A: This constant comes from unit conversion (1 HP = 550 ft-lb/s) and conversion to RPM.

Q3: What's typical motor efficiency?
A: Ranges from 0.75 for small motors to 0.95 for large premium efficiency motors.

Q4: How do I find motor current?
A: Use nameplate data or measure with a clamp meter under load.

Q5: Does this work for DC motors?
A: The power formula works for DC (set PF=1), but torque formula is universal.