Basic Cascade Controller; Master/Follower And Mixed Pump Configurations - Danfoss VLT AQUA Operating Instructions Manual

Application Types
flow condition and activate Sleep Mode, the action takes
place at raising edge of the external signal applied
(otherwise the frequency converter would never come out
of Sleep Mode again as the signal would be steady
connected).
Implementation and configuration of Sleep Mode depends
on the hardware configuration and the requirements.

2.3.1 Basic Cascade Controller

For Basic Cascade applications can be used and configured
exactly as it is described for single pump applications in
the Programming Guide. See descriptions of the parameter
groups 22-2*, 22-3* and 22-4* for further details.
Low Speed Detection as well as Low Power Detection in
combination with the timers for minimum run time,
minimum sleep time and the boost feature are supported.
The feedback from the pressure transducer is monitored
and when this pressure has dropped with a set percentage
below the normal set point for pressure (22-44 Wake-up
Ref./FB Difference), the motor will ramp up again and
pressure will be controlled for reaching the set value.
2.3.2 Master/Follower and Mixed Pump
Configurations
In multiple drive applications two different ways of the
Sleep Mode can be used.
It is possible to use the Sleep Mode as it is described for
the Basic Cascade Controller. For this configuration it is
essential, that the drive with the cascade controller option
is the last drive running after de-staging. This is achieved
by giving the connected pump the highest priority in the
parameters for runtime balancing ( e.g. by programming
the drive with the MCO 101 or the MCO 102 as "Balanced
Priority 1" and all other drives/pumps as "Balanced Priority
2" in 27-16 Runtime Balancing).
The other way makes usage of the Stage Off speeds in
parameter group 27-3* Staging Speed. This method requires
no special priority settings and therefore allows the
balancing of the running hours for all pumps.
In the following example the Sleep Mode in a Master/
Follower application is entered at 30 Hz.
Stage ON [Hz]
Stage 1 48.5 (i.e. parameter 2732.1)
Stage 2 48.5 (i.e. parameter 2732.2)
Stage 3 48.5 (i.e. parameter 2732.3)
Table 2.4
®
VLT AQUA Drive MCO 101/MCO 102
Stage OFF [Hz]
30 (i.e. parameter 2734.1)
40 (i.e. parameter 2734.2)
42 (i.e. parameter 2734.3)
®
MI38C402 - VLT is a registered Danfoss trademark
This mode is activated by programming the corresponding
speed in 27-33 Stage Off Speed [RPM] or 27-34 Stage Off
Speed [Hz] respectively.
The value for this speed has to be higher than the
minimum speed in 4-11 Motor Speed Low Limit [RPM] or
4-12 Motor Speed Low Limit [Hz].
The value for the override limit in 27-21 Override Limit
causes the frequency converter to wake-up again. The
value is entered as a % of the Maximum Reference as
programmed in 3-03 Maximum Reference.
See also 6 Configuration Examples for further details and
the entire description of the required programming steps
for a Master/Follower application.
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