Additional to the eleven different power curves which can be selected also at the Delta HE 75 without the PWM module, the PWM version also has four PWM stages. In these stages, the pump can be controlled with an external speed control. You can download the Delta HE 75 manual in our download area to find out more about the PWM function. The PWM control signal is also described in detail here. The LCD display shows the current power consumption, the selected characteristic curve and the night reduction.