English
52
WILO SE 02/2014
“external off” signal and no fault, at least the base-load pump runs at
minimum speed (Fig. 4a). If the power requirement can no longer be
met by this pump at the speed that can be set in menu 1.2.3.1,
another pump starts when the reference setpoint is undershot (see
Fig. 3, item 1) and takes over the speed control (Fig. 4b). The previous
base-load pump continues to run at max. speed as a peak-load pump.
This procedure is repeated with increasing load until the maximum
number of pumps is reached (here: 3 pumps – see Fig. 4c).
If the requirement drops, then the controlling pump is switched off
when the speed that can be set in menu 1.2.3.2 is reached and the
reference setpoint is exceeded at the same time; then, a former peak-
load pump takes over control.
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 pump.
Pump cycling
Various mechanisms of pump cycling are applied optionally in order to
ensure that the loads on all pumps are as uniform as possible and to
balance the running times of the pumps.
The base-load pump is cycled on each requirement (after deactiva-
tion of all pumps).
Furthermore, a cycling of the base-load pump can also be activated
(menu 5.6.1.0). The running time between 2 cycling procedures can
be set in menu 5.6.2.0.
Standby pump
One pump can be defined as the standby pump. When this operating
mode is activated, this pump is not activated in normal operation. It is
switched on only if a pump fails due to a fault. However, the standby
pump is subject to standstill monitoring and is included in the test run.
Service life optimisation ensures that every pump becomes a standby
pump once.
This function is preset at the factory and can be changed only 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 two 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 happens when the system is at standstill. A test run
does
not
happen when the switchgear is in “external off” status.
Low water
(only for control mode
Δ
p-c)
A low-water signal can be fed to the control system via a normally
closed contact by means of the signal from a suction-side pressure
switch or break tank float switch. 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, this does not lead to deac-
tivation.
The system restart after a deactivation due to low water is performed
automatically after the signal input closes (delay time acc. to menu
1.2.5.5).
The fault signal is reset automatically after the restart. However, it can
be read out from the history memory.
Monitoring of maximum and mini-
mum pressure (only for control mode
Δ
p-c)
The limit values for safe system operation can be set in menu 5.4.0.0.
Exceeding the maximum pressure (menu 5.4.1.0) leads to delayed
(menu 5.4.4.0) deactivation of all pumps. The collective fault signal is
activated.
Normal operation is enabled again after the pressure has dropped
below the activation threshold.
Summary of Contents for SC-HVAC SC
Page 2: ......
Page 3: ...Fig 1a 1 2 4 3 Fig 1b 1 2 4 5 3...
Page 4: ...Fig 1c 1 2 4 5 3 Fig 1d 1 1 2 4 5 3...
Page 5: ...Fig 1e 1 2 4 6 7 8 5 3 Fig 1f 1 1 2 4 6 7 8 3 5...
Page 55: ......
