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25-55 Alternate if Load < 50%
Option:
Function:
If Alternation If Capacity <50% is enabled, the pump alternation can only occurs if the capacity is
equal to or below 50%. The capacity calculation is the ratio of running pumps (including the variable
speed pump) to the total number of available pumps (including variable speed pump, but not those
interlocked).
Capacity
=
NRUNNING
NTOTAL
× 100 %
For the Basic Cascade Controller all pumps are equal size.
[0]
Disabled
The lead pump alternation will take place at any pump capacity.
[1] *
Enabled
The lead pump function will be alternated only if the numbers of pumps running are providing less
than 50% of total pump capacity.
NB!
Only valid if par.25-50
is different from
Off
[0].
25-56 Staging Mode at Alternation
Option:
Function:
[0] *
Slow
[1]
Quick
This parameter is only active if the option selected in
Lead Pump Alternation
, par. 25-50, is different
from
Off
[0]
Two types of staging and destaging of pumps are possible. Slow transfer makes staging and de-
staging smooth. Quick Transfer makes staging and destaging as fast as possible; the variable speed
pump is just cut out (coasted).
Slow
[0]: At alternation, the variable speed pump is ramped up to maximum speed and then ramped
down to a stand still.
Quick
[1]: At alternation, the variable speed pump is ramped up to maximum speed and then coas-
ted to stand still.
The below examples show Alternation in both Quick and Slow configurations.
Illustration 2.7: Slow Configuration
2 Parameter Description
VLT
®
AQUA Drive Programming Guide
222
MG.20.O4.02 - VLT
®
is a registered Danfoss trademark
2