English
54
WILO SE 02/2014
Fault-actuated switchover of multi-
pump system
SC switchgear with frequency converter (FC):
If the base-load pump has a fault, it is switched off and another pump
is switched onto the frequency converter. If the frequency converter
has a fault, the switchgear works like an SC switchgear without fre-
quency converter.
SC switchgear without frequency converter:
If the base-load pump has a fault, it is switched off and one of the
peak-load pumps is managed by the control system as a base-load
pump.
SCe switchgear:
If the base-load pump has a fault, it is switched off and another pump
takes over the control function.
A fault of a peak-load pump always leads to its deactivation and to
the activation of another peak-load pump (possibly also the standby
pump).
6.2.2
Control modes
The basic control mode of the system can be preselected in menus
1.1.1.0 to 1.1.1.8.
An electronic signal transmitter (measurement range to be set in
menu 5.2.1.0) supplies the control variable actual value, e.g. as a
4...20 mA current signal. For the devices with temperature sensor
inputs, the resistance change of Pt100 or Pt1000 sensors is detected
(depending on the jumper setting; see Fig. 5).
The following control modes can be selected:
p-c (constant differential pressure – see Fig. 6)
The differential pressure (between two system points) is held con-
stant in accordance with the setpoint under changing load conditions
(volume flow).
Multi-pump operation is possible.
p-v (variable differential pressure – see Fig. 7) (only SCe/SC…FC)
The control setpoint of the exclusively running base-load pump is
adjusted and corrected as a function of the volume flow between
Hmin (menu 1.2.1.3) and setpoint (setpoint
≥
Hmin
≥
0.4 x setpoint).
Furthermore, the zero-delivery head (H0) of the pump must be input
(menu 1.2.1.1).
After load-sensitive cut-in of one or more peak-load pumps, the sys-
tem operates in the
p-c mode.
Multi-pump operation is possible. External analogue setpoint specifi-
cation is possible.
p-c (constant absolute pressure – see Fig. 8)
The output pressure of the system is held constant in accordance with
the setpoint under changing load conditions (volume flow).
Multi-pump operation is possible.
T-c (constant differential temperature – see Fig. 9)
The differential temperature (between two system points; feed/
return) is held constant in accordance with the setpoint under chang-
ing load conditions (volume flow).
Multi-pump operation is possible.
Содержание SC-HVAC SC
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