Avoid common mistakes when replacing

Many people base their decision on power (kW) when replacing a motor, but focusing solely on power (kW) is a mistake that can result in the new motor not fitting physically or functioning properly in the application. More information is needed to find the right replacement motor.

This is important to keep in mind when replacing an electric motor

Power – use the same power setting.
Read more below.
RPM – The correct RPM is very important. The most common RPMs are 2-pole (≈2,800 rpm) and 4-pole (≈1,400 rpm).
Read more below.
Mounting – A motor can be mounted in many different ways. Common options include B3 (foot), B5 (large flange), or B14 (small flange).
Read more below.
Shaft – the diameter, length, and keyway must match the coupling.
Read more below.

Effect

Normally, you should choose a motor with the same power rating as the one being replaced. You may be able to go up one power rating if the size is correct. Do not choose a lower power rating unless you are certain that the actual power requirement is lower.

RPM

The following approximate RPM values apply at a frequency of 50 Hz:

2-pole ≈ 2,800 rpm
4-pole ≈ 1,400 rpm
6-pole ≈ 950 rpm
8-pole ≈ 700 rpm

At a frequency of 60 Hz, the rotational speed is 20% higher

Assembly

The most common standard assemblies

B3 (IM 1001): A pure foot motor that is mounted on feet.
B5 (IM 3001): A flange-mounted motor with a large flange and through-hole mounting.
B14 (IM 3601): A flange-mounted motor with a small flange and threaded mounting holes.
B14M: A variant known as the small-flange medium (B14 medium-flange).
B35 (IM 2001) A motor with both a base and a B5 flange.
B34 (IM 2101) A motor with both a foot and a B14 flange.

There are many more variations. If the motor is equipped with drain holes, its physical orientation is important to ensure that the drain holes are positioned at the lowest point.

Axel

The shaft must fit the clutch or pulley on your machine. Three things to check: