Instruction manual

Cascade Controller Option
System
Optimization
■ System Optimization
■ 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 M enu 041 Par. 422 PID star t-up frequency
(PID START VALUE)
Value:
f
MIN
-f
MAX
(parameters 201 and 202)
✭ 0Hz
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 042 Par. 427 PID lowpass filter time
(PID FILTER TIME)
Value:
0.01 - 10.00
✭ 1.00
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
frequency equals ½πt. For example, if a time constant
of 0.1 s is programmed, the cut off frequency for the
lowpass filter will be 1/[2π (.1)] = 1.6 Hz.
The PID controller will then only respond to changes in
the feedback signal whose frequency is less than 1.6 Hz.
MG.60.I5.22 - VLT is a registered Danfoss trademark
57