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System Optimisation
System start up and final adjustments
After Master drive and slave programming is
complete, and after all system safety procedures
have been ensured and the system is operational,
final adjustments can be made to reach maximum
efficiency for drive and cascade controller operation.
Final adjustments involves the following:
a. Setting the best efficiency frequency in the cascade
controller for staging and destaging pumps and fans
b. Optimization of the process regulator
Best efficiency frequency
Quick Menu 036 Par. 422 PID start-up frequency
(PID START VALUE)
Value:
f
-f
(parameters 201 and 202)
MIN
MAX
Function:
Each time the drive is given a start command, the start
up frequency is the speed the drive accelerates to
before PID control is activated. The drive will follow the
acceleration ramp when a start signal is received as if
in open loop. When the programmed start frequency
is reached, it will change to closed loop operation.
Description of choice:
Set the required start frequency. A setting near the
operating speed will enable the system to stabilize
more quickly. For pump applications, set this high
enough to ensure flow from the pump.
Quick Menu 037 Par. 427 PID lowpass filter time
(PID FILTER TIME)
Value:
0.01 - 10.00
Function:
Noise on the feedback signal can be reduced
with the lowpass filter.
Description of choice:
Select the desired time constant (t). The cut off
p
frequency equals
t. For example, if a time constant
of 0.1 s is programmed, the cut off frequency for
the lowpass filter will be 1/[2
52
0 Hz
1.00
p
(.1)] = 1.6 Hz.
Cascade Controller Option
The PID controller will then only respond
to changes in the feedback signal whose
frequency is less than 1.6 Hz.
MG.60.I3.02 - VLT is a registered Danfoss trademark
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