A) Solution without drive
The motor turns at fixed speed according to the frequency network and the number of poles.
Example : 3600 Rpm for 60 Hz
Motor 2 poles
The only way to adjust the Flow is a restriction device (damper) generating losses
B) Energy Saving Solution with drive
The Drive (named also frequency inverter) allow to varies the frequency therefore the motor speed.
The Flow is directly proportional to the speed.
Damper or valve are not any more needed
C) Energy Consumption with and without drive
Example for Fan Application
Variable speed drive
50% of Energy saving at 80% of the nominal flow
Example for Pump Application
30% of Energy saving at 80% of the nominal flow