A high-kW electric motor running at 1500 rpm is, with its four-pole design, industry's most widely used drive solution. On a 50 Hz supply a 4-pole motor has a synchronous speed of 1500 rpm, and this speed naturally suits the torque-speed needs of many applications such as pumps, fans, conveyors and mixers.

Why 1500 rpm?

1500 rpm is a balanced point between the high-speed 2-pole (3000 rpm) and the low-speed 6-pole (1000 rpm). At this speed the motor runs with reasonable torque, quietly and with low vibration; since most gearboxes and belt-pulley systems are designed around this speed, mechanical matching is easy.

High kW and the Torque Relationship

Torque is set by the ratio of power to speed; at the same kW, a 1500 rpm motor produces higher torque than a 3000 rpm one. That is why a 4-pole high-kW motor is preferred for high-inertia loads or those needing a high starting moment. On directly coupled systems this can reduce the need for an extra gearbox.

Strength and Cooling

At high kW, the cast iron frame damps vibration and keeps the bearings aligned. IC411 fan cooling, Class F insulation and S1 continuous duty let the motor run non-stop at full load. IP55 protection safely shields the windings in dusty and humid environments.

Choosing a 4-Pole High-kW Motor

DRG Motor offers 1500 rpm (4-pole) high-kW motors from 30 to 355 kW in IE3 efficiency class, with cast iron frame and B3/B5 mounting options. Share your load's power and torque needs and we can settle on the right speed and configuration together.