Wilo Control SC-Booster Instrucciones De Instalación Y Funcionamiento página 81

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Please see Fig. 6 for typical default values for
the setpoint at zero flow. The procedure can
be descried according to the following example
involving a SiBoost Smart 3Helix VE604:
based on the reference setpoint
be used is selected (here: 5 bar).
The point of intersection between this curve
and the maximum volume flow of the unit
(here 3x6 = 18 m³/h) is used to determine the rel -
ative setpoint at zero flow
NOTICE:
To prevent an inadequate supply, the setpoint at
zero flow must be greater than the geodesic head
of the highest tap.
If there is no "Ext. Off" message, no fault and the
drives are activated (menu 3.1.0.0), one or more
(see menu 1.1.3.0) speed-controlled pumps
(Fig. 7) will start when the activation threshold is
œ
undershot (menu 1.2.2.1). The pumps run at a
common, synchronous speed. Only pumps that
are switching on or off may briefly run at a differ -
ent speed.
Depending on the hydraulic output requirements
of the system, the number of running pumps var -
ies and their speed is controlled so that the p-v
›
setpoint curve
controller minimises the energy demand of the
unit.
If only one pump is still active and the demand
continues to decrease, this base-load pump
switches off when the deactivation threshold is
ž
exceeded ( menu 1.2.2.2) and after the delay
time has expired (menu 1.2.5.1), if necessary fol -
lowing a zero-flow test.
Delay times can be set in the menus 1.2.5.2 and
1.2.5.3 for activation and deactivation of the
peak-load pumps.
Zero-flow test (only SC...FC and SCe versions)
When only one pump is operating in the lower fre -
quency range and with a constant pressure, a
zero-flow test is performed cyclically by briefly
increasing the setpoint to a value above the
deactivation threshold of the base-load pump
(menu 1.2.2.2). If the pressure does not drop again
after the higher setpoint is withdrawn, this means
there is zero flow and the base-load pump is
switched off after the follow-up time has expired
(menu 1.2.5.1).
In the p-v control mode, a potential zero flow
reduction is tested by reducing the setpoint. If the
actual value falls to the new setpoint during the
reduction, there is no zero flow.
The parameters of the zero-flow test are preset at
the factory and can only be changed by Wilo cus -
tomer service.
10
›
, the curve to
œ
ž
(here 87.5 %).
is followed. In doing so, the
Pump cycling
Various pump cycling mechanisms are used selec -
tively to ensure that the load is distributed as
evenly as possible between all pumps and to
thereby balance the running times of the pumps.
The base-load pump is cycled for each require -
ment (after deactivation of all pumps).
Furthermore, a cycling of the base-load pump is
also activated at the factory (can be deactivated in
menu 5.6.1.0). The running time between
2 cycling procedures can be set in menu 5.6.2.0.
Standby pump
It is possible to define one or more pump(s) as a
standby pump(s). When this operating mode is
activated, this/these pumps is/are not activated
in normal operation – activation only occurs if
another pump malfunctions due to a fault. How -
ever, the standby pumps are subject to standstill
monitoring and are included in the test run. Ser -
vice life optimisation ensures that every pump
becomes a standby pump once.
No standby pump is provided for at the factory.
This can only be modified by Wilo customer
service.
Pump test run
A cyclic test run of the pumps can be activated
in order to avoid lengthy standstill periods
(menu 5.7.1.0). The time between 2 test runs can
be defined in menu 5.7.2.0 for this purpose. In the
SCe and SC...FC versions, the speed of the pump
(during the test run) can be set (menu 5.7.3.0).
A test run only takes place when the system is at a
standstill (after zero-flow cut-off), and does not
occur when the switchgear is in the "Ext. Off"
status.
Low water
A low water signal can be sent to the control sys -
tem via a normally closed contact by means of the
signal from a suction-side pressure switch or
break tank float switch. In the case of "SCe NWB"
units, the supply pressure is monitored by an ana -
logue supply pressure sensor. The pressure
threshold for dry run detection can be defined in
menu 5.4.6.0. The digital low water contact can be
used in addition to the supply pressure sensor.
The pumps are switched off after a delay time that
can be set in menu 1.2.5.4 has expired. If the signal
input is closed again within the delay time (or the
supply pressure exceeds the pressure threshold in
5.4.6.0 – only for "SCe NWB"), this does not lead
to deactivation.
The system restart after a deactivation due to low
water is performed automatically after the signal
input closes or the supply pressure threshold for
cancelling the dry run (menu 5.4.7.0) is exceeded
(delay time acc. to menu 1.2.5.5).
WILO SE 09/2018