Danfoss VLT HVAC Series Programming Manual page 271

VLT ® HVAC Drive Programming Guide
NOTE!
Only valid if par.25-50
25-56 Staging Mode at Alternation
Option:
[0] * Slow
[1] Quick
The below figure is an example of the slow transfer staging. The variable speed pump (top graph) and one fixed speed pump (bottom graph) are running
before the staging command. When the
par.4-13 Motor Speed High Limit [RPM]
Run Next Pump Delay
Pump" (par.25-58
the "Delay Before Running On Line Power" (par.25-59
Motor Speed Low Limit and then allowed to vary speed to maintain system pressure.
25-58 Run Next Pump Delay
Range:
0.1 s* [0.1 - 5.0 s]
Lead Pump Alternation
is different from
Function:
This parameter is only active if the option selected in par.25-50
Off
from [0].
Two types of staging and de-staging of pumps are possible. Slow transfer makes staging and de-
staging smooth. Quick transfer makes staging and de-staging as fast as possible; the variable speed
pump is just cut out (coasted).
At alternation, the variable speed pump is ramped up to maximum speed and then ramped down
to a stand still.
At alternation, the variable speed pump is ramped up to maximum speed and then coasted to stand
still.
Slow [0] transfer command is activated, an alternation is carried out by ramping the variable speed pump to
or par.4-14 Motor Speed High Limit [Hz]
) the next lead pump (middle graph) is accelerated and another original lead pump (top graph) is added after
Run-on Line Delay
) as a fixed speed pump. The next lead pump (middle graph) is decelerated to
Function:
This parameter is only active if the option selected in par.25-50
from Off [0].
This parameter sets the time between stopping the old variable speed pump and starting another
pump as a new variable speed pump. Refer to par.25-56
for description of staging and alternation.
MG.11.C6.22 - VLT ® is a registered Danfoss trademark
Off
[0].
, and then decelerated to zero speed. After a "Delay Before Starting Next
Staging Mode at Alternation
3 Parameter Description
Lead Pump Alternation
is different
Lead Pump Alternation
, is different
, the illustration
3
3-247