Program features 59
Diagnostics
Parameters 04.01…04.05 (page 123), 04.20…04.25 (page 123) and 06.20 Pump
status word (page 130).
Sleep function
The sleep function is suitable for PID control applications where the consumption
varies, such as clean water pumping systems. When used, it stops the pump
completely during low demand, instead of running the pump slowly below its efficient
operating range. The following example visualizes the operation of the function.
The drive controls a pressure boost pump. The water consumption falls at night. As a
consequence, the process PID controller decreases the motor speed. However, due
to natural losses in the pipes and the low efficiency of the centrifugal pump at low
speeds, the motor would never stop rotating. The sleep function detects the slow
rotation and stops the unnecessary pumping after the sleep delay has passed. The
drive shifts into sleep mode, still monitoring the pressure. The pumping resumes
when the pressure falls under the predefined minimum level and the wake-up delay
has passed.
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