3.23.4 25-4* Staging Settings
Parameters determining conditions for staging/de-staging the pumps.
25-40 Ramp-down Delay
Range: Function:
10.0 s* [0.0 - 120.0 s] 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.
Only to be used if
Soft Starter
[1] is selected in par.25-02
Motor Start
.
25-41 Ramp-up Delay
Range: Function:
2.0 s* [0.0 - 12.0 s] 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
Motor Start
.
25-42 Staging Threshold
Range: Function:
0 %* [0 - 100 %] 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
Motor Speed Low Limit [RPM]
or par.4-12
Motor Speed
Low Limit [Hz]
, to the par.4-13
Motor Speed High Limit [RPM]
or par.4-14
Motor Speed High Limit
[Hz]
, expressed in percent.
Staging Threshold must range from
STAGE
%
=
LOW
HIGH
× 100 %
to 100%, where n
LOW
is Motor Speed Low Limit and n
HIGH
is Motor Speed High Limit.
3 Parameter Description VLT
®
HVAC Drive Programming Guide
3-242
MG.11.C6.22 - VLT
®
is a registered Danfoss trademark
3
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