English
24
Wilo AG 03/2006
6.1.3 System operating modes
Normal operation (see fig. 3)
An electronic pressure sensor (Adjustment of
measure range in menue 3.3.2.4) provides the
actual system pressure value as a 4 - 20 mA cur-
rent signal. The controller then keeps the system
pressure constant by comparing the desired
(adjustment of setpoint
➄
: see menue 3.3.2.1)
and actual values.
If there is no "External Off" message and no fault,
the speed controlled base load pump will start up
if required. Here the speed of the pump depends
on consumption.
If the power requirements of this pump can't be
met, a second (peak load) pump is switched on.
With increasing requirement further peakload
pumps will be switched on. The peak load pumps
operates then with fixed, maximum speed on line
while the speed controlled base load pump allows
the fine regulation to the desired pressure set-
point value
➆
according to the increase. If the
requirement drops such that the controlling pump
is operating in its lower power range and is not
needed to meet requirements, one peak load
pump after the other switches off. At last the base
load pump switches off by the zero flow detec-
tion. With decreasing system pressure under the
setpoint, the system switches on again.
The relevant parameter settings for the switching
on and off of the peak load pumps can be adjusted
(Switching levels
➇
/
➈
; Time delays) in menue
3.3.3.2.
To avoid pressure peaks when switching pumps
on or -breaks when switching pumps off, the
rotation speed of the base load pump can be
decreased or increased during the switching
actions. The adjustments of this so called peak fil-
ters can be done in menue 3.3.5 - page 2.
Normal operation of panels without FC
(see fig. 4)
Panels without or with faulty frequency convert-
ers are calculating the controlled variable by com-
paring the actual with the required value, too. Due
to the fact that there is no speed controlled pump,
they are working as two point controllers only
between values
➃
and
➄
/
➅
.
The switching on and off from pumps is done in
the same way as described above. To switch off
the base load pump in menue 3.3.3.1 a separate
switching level
➅
can be adjusted.
Zero amount disconnection
If just one pump is operating, a check is made
every 60 s to see whether the pressure is still
decreasing. Firstly the desired pressure value is
increased slightly for a brief time of 5 s and then
returned to its previous value. If the system's
actual pressure value then remains at the higher
level, a zero amount is present. The pump is then
switched off after a variable delay time (menue
3.3.3.1). If the pressure falls below the desired
value, the system starts up again.
In operation without frequency convertor the
base load pump is switched off when the second
switch off level (see above) is reached and the
time delay is over.
Decreases the system pressure under the switch-
ing on level, the system starts up again.
Pump change
To enable an equalized utilization and running
time of the pumps, different mechanismens will
take action. The adjustment can be done in menue
3.3.4.2.
For a
time dependant pump change
the system
will preselect the base load pump in dependancy
from the running hours counters and the diagnosis
system (faults, releases)(run time optimization).
The adjustable time is the maximum run time dif-
ference.
The
cyclic pump change
leads to a pump change
after a fix adjusted time regardless of the actual
running hours of a single pump.
Changing pumps by
impulse
every restart
changes the base load pump regardless of the
actual running hours of a single pump.
With
Preselection Pump
a pump can be perma-
nently designated as base load pump.
Independent from the changing mechanism of the
base load pump the peak load pumps are continu-
ously changed run time optimisated. This means
that the pump with the lowest run time is started
first and switched off as last one when require-
ment decreases.
Reserve pump
Parameterisation of the installation via Menue
3.3.4.1 allows one of the pumps to be designated
as reserve pump. In reserve mode, one of the
pumps does not participate in the standard oper-
ating cycle. This pump is only activated when
another pumps fails to allow the demand to be
met. The run time optimization ensures that each
pump will once serve as reserve pump. The reserve
pump is triggered by the pumpkick function, too.
Pumpkick (Test run)
To avoid a stand still of pumps for long durations a
cyclic test run is activated. In the menue 3.3.4.3
the time between two testruns and the duration
of a testrun can be adjusted. A testrun will only be
executed during the stand still of the system (after
zero flow shut off)
Changeover upon fault in multi-pump
system
• Systems with frequency converter:
If the base load pump generates an error, it will
be switched off immediately and a peak load
pump is connected to the converter . If the fre-
quency converter fails, the system is switched into
the operation mode "automatic without fre-
quency con-verter" with the adequat controller
characteristic.
Summary of Contents for Wilo-CC-System
Page 2: ...Fig 1 1 Fig 1 2...
Page 3: ...Fig 2 Fig 3 Fig 4...
