Operating instructions
NOTE
Only valid if par. 25-50 Lead Pump Alternation is different
from Off [0].
25-56 Staging Mode at Alternation
Option: Function:
This parameter is only active if the option selected in
par. 25-50 Lead Pump Alternation is different from Off
[0].
Two types of staging and destaging of pumps are
possible. Slow transfer makes staging and destaging
smooth. Quick Transfer makes staging and destaging
as fast as possible; the variable speed pump is just cut
out (coasted).
[0]
*
Slow At alternation, the variable speed pump is ramped up
to maximum speed and then ramped down to a stand
still.
[1] Quick At alternation, the variable speed pump is ramped up
to maximum speed and then coasted to stand still.
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 Slow [0] transfer command is activated,
an alternation is carried out by ramping the variable speed
pump to par. 4-13 Motor Speed High Limit [RPM] or
par. 4-14 Motor Speed High Limit [Hz], and then decelerated to
zero speed. After a “Delay Before Starting Next Pump”
(par. 25-58 Run Next Pump Delay) the next lead pump (middle
graph) is accelerated and another original lead pump (top
graph) is added after the “Delay Before Running On Mains”
(par. 25-59 Run on Mains Delay) as a fixed speed pump. The
next lead pump (middle graph) is decelerated to Motor Speed
Low Limit and then allowed to vary speed to maintain system
pressure.
25-58 Run Next Pump Delay
Range: Function:
0.1 s
*
[0.1 -
5.0 s]
This parameter is only active if the option selected
in par. 25-50 Lead Pump Alternation, is different
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 Staging Mode at Alternation, the illustra-
tion for description of staging and alternation.
25-59 Run on Mains Delay
Range: Function:
0.5 s
*
[Applica-
tion
dependant]
This parameter is only active if the option
selected in par. 25-50 Lead Pump Alternation,
is different from Off [0].
This parameter sets the time between
stopping the old variable speed pump and
starting this pump as a new fixed speed
pump. Refer to par. 25-56 Staging Mode at
Alternation, the illustration for description of
staging and alternation.
3.23.5 25-8* Status
Readout parameters informing about the operating status of
the Cascade Controller and the pumps controlled.
25-80 Cascade Status
Range: Function:
0
*
[0 - 0 ] Read out of the status of the Cascade Controller.
25-81 Pump Status
Range: Function:
0
*
[0 -
0 ]
Pump Status shows the status for the number of
pumps selected in par. 25-06 Number of Pumps. It is a
readout of the status for each of the pumps showing a
string, which consists of pump number and the current
status of the pump.
Example: Readout is with the abbreviation like “1:D
2:O” This means that pump 1 is running and speed
controlled by the frequency converter and pump 2 is
stopped.
25-82 Lead Pump
Range: Function:
0
*
[Application
dependant]
Readout parameter for the actual variable speed
pump in the system. The Lead Pump parameter
is updated to reflect the current variable speed
pump in the system when an alternation takes
place. If no lead pump is selected (Cascade
Controller disabled or all pumps interlocked) the
display will show NONE.
Parameter Description
VLT
®
HVAC Drive Programming Guide
MG.11.CA.02 - VLT
®
is a registered Danfoss trademark 175
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