Danfoss VLT HVAC Series Programming Manual page 266

3 Parameter Description
3.23.4 25-4* Staging Settings
Parameters determining conditions for staging/de-staging the pumps.
25-40 Ramp-down Delay
Range:
10.0 s* [0.0 - 120.0 s]
3
25-41 Ramp-up Delay
Range:
2.0 s* [0.0 - 12.0 s]
25-42 Staging Threshold
Range:
0 %* [0 - 100 %]
3-242
Function:
When adding a fixed speed pump controlled by a soft starter, it is possible to delay the ramp-down
of the lead pump until a preset time following the start of the fixed speed pump in order to eliminate
pressure surges or water hammering in the system.
Soft Starter
Only to be used if [1] is selected in par.25-02
Function:
When removing a fixed speed pump controlled by a soft starter, it is possible to delay the ramp up
of the lead pump until a preset time after stopping the fixed speed pump to eliminate pressure
surges or water hammer in the system.
Only to be used if Soft Starter [1] is selected in par.25-02
Function:
When adding a fixed speed pump, in order to prevent an overshoot of pressure, the variable speed
pump ramps down to a lower speed. When the variable speed pump reaches the "Staging Speed"
the fixed speed pump is staged on. The staging threshold is used to calculate the speed of the
variable speed pump when the "cut-in point" of the fixed speed pump occurs. The calculation of the
staging threshold is the ratio of par.4-11
Low Limit [Hz] Motor Speed High Limit [RPM]
, to the par.4-13
[Hz] , expressed in percent.
Staging Threshold must range from
STAGE
to 100%, where n is Motor Speed Low Limit and n
LOW
MG.11.C6.22 - VLT ® is a registered Danfoss trademark
VLT ® HVAC Drive Programming Guide
Motor Start
.
Motor Start .
Motor Speed Low Limit [RPM]
or par.4-12
Motor Speed High Limit
or par.4-14
LOW
= × 100 %
HIGH
%
is Motor Speed High Limit.
HIGH
Motor Speed