The main criteria when choosing an electric motor are the application, the required power (kW), speed, energy-efficiency class (IE3/IE4/IE5), mounting type, protection rating (IP) and the conditions of the operating environment. A correctly selected motor delivers energy savings, long life and uninterrupted operation.

Electrical and performance criteria

  • Power and torque: assess the machine's continuous load together with its starting torque requirement.
  • Speed: choose 2, 4, 6 or 8 poles, and match with a gearbox or inverter if necessary.
  • Supply: single or three phase, voltage (e.g. 230/400 V, 400/690 V) and frequency (50/60 Hz).
  • Efficiency: for long running hours, IE3 and higher classes reduce operating costs.
  • Duty type: S1 for continuous operation; choose the appropriate duty type for frequent starts and stops.

Mechanical and environmental criteria

  • Mounting type: B3 foot-mounted, B5 large flange, B14 small face flange, B35 foot and flange.
  • Frame size and shaft: the IEC frame number, shaft diameter and key size must suit the machine.
  • Frame material: cast iron for heavy, vibrating duties; aluminium where low weight matters.
  • Protection and insulation: IP55 or higher for dusty and humid sites, and class F insulation.
  • Environment: high ambient temperature and altitude reduce cooling capacity, so derating must be considered in these conditions.

Common mistakes

Choosing a heavily oversized motor, looking only at the purchase price, failing to check mounting dimensions and not mentioning inverter operation are the most frequent errors. The DRG Motor technical team helps you make the right choice in terms of both performance and cost by identifying the most suitable motor for your application.

For help with motor selection, contact us on +90 (542) 666 11 11 (WhatsApp) or at info@drgmotor.com.