This is a comparison of two condensers, each with eight axial fans. To configure the respective optimal cooling capacity for different cooling requirements, the airflow is adjusted.

With on/off operation, individual fans are switched on and off by external switching devices in order to attain the desired utilization. The fans that remain in operation continue to run at full speed.

ebm-papst EC technology enables continuous adjustment of the speed to the demand. Thus all fans remain in operation, resulting in substantial power savings. The graphics below show the possible energy savings and noise reduction in direct comparison of on/off operation and continuous speed adjustment:

Low energy consumption: The bars show the power input of fans that are switched on or off. The blue line shows the power input with continuous speed adjustment.   Lower noise: While shutting off half of the fans (one-half of the air flow) decreases the noise level by approximately 3 dB, speed reduction to one-half the air flow attains an improvement of 15 dB.