Motor Sizing and Selection Guide
Learn how to size AC and DC motors for industrial applications. Covers power, torque, speed, and protection.
Power Requirements
Calculate required power from load torque and speed: P (kW) = T × n / 9550. For pumps and fans, consider starting torque and duty cycle. Always add 10–15% safety margin for variable loads.
Voltage and Enclosure
Match motor voltage to supply (400V 3-phase, 230V single-phase). Choose IP54 or IP55 for harsh environments. IEC standard frame sizes (IEC 34) ensure interchangeability.
Protection Components
Use thermal overload relays (e.g. LRT, 3RU2) sized to motor full-load current. Main contactor (LC1D, 3RT2) must handle inrush current. Consider soft starters for high-inertia loads.
