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3.2.4 Setpoint
Operation with PFU 2000 RAM / PMU 2000 Settings:
The maximum setpoint is set in "setpoint max." (display 200).
This value is the upper limit of the setpoint and forms the basis of
the calculation of "setpoint act." (display 401) which takes all set-
point influences into account. The product of "setpoint max." and
all setpoint influences forms "setpoint act.", which is the actual
setpoint according to which the closed-loop controller operates.
If the zone has been set to "local" (display 300), "setpoint max."
can be set by means of the function selector in the PFU 2000.
"Setpoint max1" (display 222) will be activated if it is set to "on"
and the PFU 2000 input 4 contact is closed.
"Setpoint max1" functions like "setpoint max.", but it cannot be in-
fluenced by the clock program.
The setting range of "setpoint max." and "setpoint max1" is equal
to the measuring range of the actual transmitter.
Operation with PFU 2000 EPROM Settings:
The setpoint is set by means of the function selector in the PFU
2000 which has three positions, see fig. 13.
•
"STOP"
All pumps are stopped and no setpoint is set. Fault indications
will be reset.
•
"0% to 100%"
By means of the function selector the required pressure can
be set within the range from 0% to 100%. 100% corresponds
to the maximum value of the transmitter.
•
"MAX"
The PFU 2000 starts all pumps at maximum performance. All
internal monitoring functions are active. Remotely set set-
points or external on/off are not active.
Fig. 13
Function Selector in the PFU 2000
Setpoint
0%
100%
STOP
MAX
14
3.2.5 Setpoint Influences
Operation with PFU 2000 RAM / PMU 2000 Settings:
In order to optimize the operation of the system, it is often advan-
tageous to operate the system with a variable setpoint instead of
a constant setpoint. The selected setpoint influences reduce "set-
point max." according to their settings.
More than one setpoint influence can be active simultaneously.
The influence types are described below. The product of all influ-
ences and "setpoint max." forms "setpoint act.".
For further information, see section
3.2.4 Setpoint.
Progressive = proportional (friction loss compensation):
If the system is to compensate for friction loss, this is possible by
selecting progressive influence.
When "progressive infl" is set to "on" (display 202), the pressure
will rise with an increasing flow. The actual flow is estimated ac-
cording to internal operating data without measuring the flow.
"Setpoint act." will be increased linearly from the adjustable per-
centage at zero flow to 100% "setpoint act." at maximum flow.
Maximum flow is the sum of the maximum flows of all the pumps
in the zone minus the standby pumps.
Fig. 14
Friction Loss Compensation
H
100 %
60 %
Setpoint Influences via External Signals:
If "influence" is selected (display 217), it is important to set the re-
quired table value.
Fig. 15
Example of Setpoint Influence Table
Set A
0 %
Set A
50 %
Set A
80 %
Set A
100 %
The following external setpoint influences are possible:
•
"off"
No setpoint influence table (clock program, progressive influ-
ence and remote control of setpoint via the PCU 2000 are pos-
sible).
• "extern" (%)
An external analog signal or potential-free contact on the PFU
2000 analog input 3 influences the setpoint in accordance with a
table.
With the PFU 2000 analog input 3 as a 0-10 V input and the set-
ting "extern" %, the input may be used as "remote on/off" for all
pumps which have not been defined as 'not to be switched off'.
If the PFU 2000 input 3 contact is:
open
= maximum value of the table.
closed = minimum value of the table.
Examples of application: Changeover to night-time duty or ana-
log setpoint control from a building management system.
Setpoint max.
Setpoint max
Q
->STOP
bar
->
1.5 bar
->
2.5 bar
->
6.0 bar
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