Danfoss VLT Automation VT Drive FC 322 Programming Manual page 244

2 Parameter Description
25-06 Number of Pumps
Range:
2* [Application dependant]
2
2.21.3 25-2* Bandwidth Settings
Parameters for setting the bandwidth within which the pressure will be allowed to operate before staging/destaging fixed speed pumps. Also includes
various timers to stabilize the control.
25-20 Staging Bandwidth
Range:
Application [Application dependant]
dependent*
25-21 Override Bandwidth
Range:
100 %* [Application dependant]
242
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Function:
The number of pumps connected to the Cascade Controller including the variable speed pump. If
the variable speed pump is connected directly to the frequency converter and the other fixed speed
pumps (lag pumps) are controlled by the two built in relays, three pumps can be controlled If both
the variable speed and fixed speed pumps are to be controlled by built-in relays, only two pumps
can be connected.
par. 25-05 Fixed Lead Pump, Fixed Lead Pump
If
one fixed speed pump; both controlled by built in relay. If
Pump Yes
, is set to [1]: one variable speed pump and one fixed speed pump controlled by built-in
relay.
One lead pump, see par. 25-05 Fixed Lead Pump
relays.
Function:
Function:
When a large and quick change in the system demand occurs (such as a sudden water demand),
the system pressure rapidly changes and an immediate staging or destaging of a fixed speed pump
becomes necessary to match the requirement. The override bandwidth (OBW) is programmed to
override the staging/destaging timer (par. 25-23
Delay
) for immediate response.
The OBW must always be programmed to a higher value than the value set in
(SBW), par. 25-20 Staging Bandwidth . The OBW is a percentage of par. and par. .
Setting the OBW too close to the SBW could defeat the purpose with frequent staging at momentary
pressure changes. Setting the OBW too high might lead to unacceptably high or low pressure in the
MG.20.W1.22 - VLT is a registered Danfoss trademark
VLT Automation VT Drive FC322
Programming Guide
No
, is set to [0]: one variable speed pump and
par. 25-05 Fixed Lead Pump, Fixed Lead
. Two fixed speed pumps controlled by built-in
SBW Staging Delay and par. 25-24 SBW Destaging
Staging Bandwidth