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8 Basic configurations of the pressure
booster system
The control unit controls several pump sets according to the configured setpoint and
bandwidth.
Pump sets are started up and stopped when the current discharge pressure is not within the
bandwidth arranged symmetrically below and above the setpoint. When none of the pump
sets of the pressure booster system are running, the first pump set is started up immediately
as soon as the current discharge pressure sinks below the setpoint minus half the
bandwidth. Further pump sets are started up as soon as this criterion is met again. Only one
further pump set is started up at a time. If a pump set is to be started up and the time since
its last start-up is shorter than the start delay time, the pump set will only start up after the
delay time.
Pump sets are stopped when the current discharge pressure exceeds the setpoint plus half
the bandwidth. Further pump sets are stopped as soon as this criterion is met again. If a
pump set is to be stopped and the time since its last stop is shorter than the stop delay time,
the pump set will only stop after the delay time. The last pump set is stopped according to
the same criterion. A pump set operated on a frequency inverter may not exceed the
setpoint plus half the bandwidth as the speed is reduced by the pressure control system to
meet the setpoint. In this case, a special function will take over, checking whether water is
still required.
When the pump set speed is below the Pump Speed for Activation (parameter 2-4-6-1) and
the current discharge pressure is within the flow detection Bandwidth (parameter 2-4-6-5) for
the Time within Bandwidth (parameter 2-4-6-2), the pump set speed is reduced by the Step
Height of Speed (parameter 2-4-6-4) for the corresponding Step Interval (parameter
2-4-6-3). If flow continues to be present, the discharge pressure falls below the bandwidth
and flow detection is deactivated. If this is not the case, the last pump set will be stopped
when the Speed for Stopping Last Pump (parameter 2-4-6-6) is reached.
8.1 F system
F system
The F system controls several pump sets running at the nominal speed required for the
setpoint.
The pump sets on duty run at full nominal speed. As the pump sets of this system are not
speed-controlled, the discharge pressure during normal operation is located in a range
around the setpoint, i.e. between the setpoint minus half the bandwidth and the setpoint plus
half the bandwidth.
During the start-up process and stop process, the discharge pressure may deviate more for
a short period of time. The Operating Mode (parameter 1-1-2-3) has to be set to "Mains
operation". Pump Groups (parameter 1-1-2-6) has to be set to "Pump-group control".
8.2 VC system
VC system
In speed-controlled systems the pump sets are controlled in such a way that the discharge
pressure is maintained at the setpoint.
Pump sets are started up and stopped when the bandwidth limits around the setpoint are
exceeded. A smaller bandwidth around the setpoint can therefore be set.
If only one pump is running, the next pump set is started up when the first pump set runs at
maximum speed and the current discharge pressure falls below the setpoint minus half the
bandwidth. The first pump set will keep running at full speed; only the newly started pump
set is speed-controlled in accordance with the setpoint. When the speed-controlled pump set
is running at minimum speed and the current discharge pressure exceeds the setpoint plus
half the bandwidth, the pump set will be stopped that has been running the longest at
maximum speed. The last pump set is stopped by the No-flow Detection function.
