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 (coas-
ted).
[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
, or 4-14, and then decelerated to zero speed. After a “Delay Before Starting Next Pump” (
par. 25-59, 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. 25-60, 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:
0.5 sec
*
[Par.25-58 – 5.0 sec]
This parameter is only active if the option selected in
Lead Pump Alternation
, par. 25-50, 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
Staging Mode at Alternation
, par. 25-56, and Figure 7-5 for description of
staging and alternation.
VLT
®
HVAC Drive Programming Guide 3. Parameter Description
MG.11.C5.02 - VLT
®
is a registered Danfoss trademark
219
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