20-94 PID Integral Time
Range:
Function:
20.00 s*
[0.01 - 10000.00 s]
Over time, the integrator accumulates a contribution to the output from the PID controller as long
as there is a deviation between the reference/setpoint and feedback signals. The contribution is
proportional to the size of the deviation. This ensures that the deviation (error) approaches zero.
Quick response on any deviation is obtained when the integral time is set to a low value. Setting it
too low, however, may cause the control to become unstable.
The value set is the time needed for the integrator to add the same contribution as the proportional
part for a certain deviation.
If the value is set to 10,000, the controller will act as a pure proportional controller with a P-band
based on the value set in par. 20-93
. When no deviation is present, the output
from the proportional controller will be 0.
22-21 Low Power Detection
Option:
Function:
[0] *
Disabled
[1]
Enabled
If selecting Enabled, the low power detection commissioning must be carried out in order to set the
parameters in group 22-3* for proper operation!
22-22 Low Speed Detection
Option:
Function:
[0] *
Disabled
[1]
Enabled
Select Enabled for detecting when the motor operates with a speed as set in par. 4-11
22-23 No-Flow Function
Common actions for Low Power Detection and Low Speed Detection (Individual selections not possible).
Option:
Function:
[0] *
OFF
[1]
Sleep Mode
The drive will enter sleep mode and stop when a No Flow condition is detected. See parameter
group 22-4* for programming options for sleep mode.
[2]
Warning
The drive will continue to run, but activate a No-Flow Warning [W92]. A drive digital output or a
serial communication bus can communicate a warning to other equipment.
[3]
Alarm
The drive will stop running and activate a No-Flow Alarm [A 92]. A drive digital output or a serial
communication bus can communicate an alarm to other equipment.
NOTE!
Do not set par. 14-20
Reset Mode
to [13] Infinite auto reset when par. 22-23
is set to [3] Alarm. Doing so will cause
the drive to continuously cycle between running and stopping when a No Flow condition is detected.
NOTE!
If the drive is equipped with a constant speed bypass with an automatic bypass function that starts the bypass if the drive experiences
a persistent alarm condition, be sure to disable the bypass’ automatic bypass function, if [3] Alarm is selected as the No-Flow Function.
VLT HVAC Low Harmonic Drive Instruction
Manual
6 How to Program the Low Harmonic Drive
MG.16.A1.22 - VLT
®
is a registered Danfoss trademark
6-37
6