7. Noise from drive motors

The aim of this section is to compare the noise of a pump with that of a motor, both in terms of level and frequency. The result is simple, practical information on the airborne noise of a pump-motor unit.

We will consider only asynchronous electric motors, which are the preferred drive mode for pumps. For simplicity's sake, the various sources of noise on this type of machine can be grouped into 4 main categories:

• magnetic and electrodynamic noise;

• mechanical noise ;

• aerodynamic noise ;

• power supply noise (non-sinusoidal waves or waves with a carrier frequency).