How to select the right motor

1. Understand Your Application Requirements

Start by gathering these key parameters:

• Load type - constant, variable, shock
• Required torque - starting, running, peak
• Speed - (RPM) requirements
• Duty cycle - continuous, intermittent, short-time
• Power supply - voltage, phase, frequency
• Environment - temperature, humidity, dust, explosion risk

2. Calculate load torque

• Rotational load - Use the formula pictured      
  • Where:
    • T = Torque in Nm
    • P = Power in kW
    • n = Speed in RPM

• Linear Load - Convert linear force to torque using gear/pulley radius.

Also consider:

• Inertia of the system (especially in accelerative/decelerative applications)
• Any frictional or gravitational loads

3. Match Speed and Torque with Motor Characteristics

Compare your required torque-speed profile to motor datasheets:

• Synchronous or asynchronous motors?
• AC or DC motor?
• Brushed, brushless or stepper motor?
• Controller required – basic, advanced or full motion control?
• Gearmotor if high torque at low speed is needed.

4. Choose Based on Power Rating and Drive Characteristics required

• Use calculated required power and apply a safety margin (typically 20–30%)
• Pick a motor with rated power ≥ adjusted power
• Check starting torque if the load is hard to start (e.g., conveyors, crushers)
• Determine control required for drive options