Grundfos DDI 150-4, Installation And Operating Instructions Manual

Page: 38 / 632

English (GB)
38
Result of weighting
In the example, the following values were entered as reference
points L
d
and H
d
:
L
d
: mA
min.
= 6 mA, Q
select mA min.
= 10 l/h
H
d
: mA
max.
= 16 mA, Q
select mA max.
= 40 l/h.
The curve for current input / current output now passes through Q
= 0 at < 6 mA, from Q = 10 l/h at 6 mA to Q = 40 l/h at 16 mA, and
through Q = 40 l/h at > 16 mA (curve 1d).
In the same way, it is also possible to enter a current weighting
with a negative gradient. In order to do this, the value pair for
reference point L must first be entered with the smaller mA value
followed by reference point H.
In the example, the following values were entered as reference
points L
e
and H
e
:
L
e
: mA
min.
= 2 mA, Q
select mA min.
= 60 l/h
H
e
: mA
max.
= 16 mA, Q
select mA max.
= 10 l/h.
The curve for current input/current output now passes through Q
= 0 at < 2 mA, from Q = 60 l/h at 2 mA to Q = 10 l/h at 16 mA, and
through Q = 10 l/h at > 16 mA (curve 1e).
Fig. 40 Result of weighting
Note down the set current weighting in the following diagram
for current input/current output:
1. Label the Q [l/h] axis for your working area.
2. Mark your reference points with the value pairs:
L: mA
min.
/ Q
select mA min.
and
H: mA
max.
/ Q
select mA max.
in the diagram.
3. Draw the curve as a line from L to H, vertically from
Q
select mA min.
to the mA axis, and horizontally from
Q
select mA max.
to the edge of the diagram.
Fig. 41 Diagram for current input / current output
9.10 Flow Monitor
9.10.1 Application notes
Dosing of degassing media (H
2
O
2
, chlorine bleaching
agents)
• For a robust operation, set the number of permissible error
strokes to a value higher than 10.
Dosing of antiscalent (viscosity higher than 20 mPa s)
• Use spring-loaded valves for high-viscosity media.
• When dosing viscous media, see also section
1.3.10 Dosing
medium .
Dosing of viscous media
• For media with a viscosity higher than 20 mPa s,
spring-loaded suction and discharge valves are
recommended.
For batch or timer operation
• Set the number of permissible error strokes to a value lower
than the number of working strokes.
• If, while the pump is stopped, the pressure in the discharge
line falls below the minimum pressure of 2 bar (e.g. in the
event of a leak in the pressure-loading valve), increase the
number of permissible error strokes so as to prevent
unnecessary error messages.
Ensuring the counter-pressure by a pressure-loading valve:
• Check the counter-pressure 2 to 3 weeks after start-up.
– If it is below 2 bar, the pressure-loading valve has to be
re-adjusted.
– If the volume flow is not constant (as, for example, in the
case of contact or analog control), even small volume flows
should not fall below the minimum pressure or minimum
pressure difference of 2 bar.
9.10.2 Setting the Flow Monitor
In order for the pressure sensor (if installed) to function as a
dosing controller, the dosing controller must be switched on.
To allow the pump to switch off in the event of overpressure and
to set the cut-off pressure of the pump, the pressure control
function must be switched on and set.
If no pressure sensor is connected, the pump determines the
pressure from the motor current.
Switching on dosing controller
Menu item "flow" is open.
– "flow OFF" appears in the display.
1. Press the "Up" button.
– "flow ON" appears in the display.
– The dosing controller is activated.
Switching on pressure control function
1. Press the "Menu/Info" button.
– Menu item "P" is open.
– "P:OFF" appears in the display.
2. Press the "Up" button.
– "P:ON" appears in the display.
– The pressure control function is activated.
TM0
3
668
3
4
5
0
6
Note
The maximum flow rate of the pump must not be
exceeded!
TM
03 66
14 450
6
0 mA 4 mA 8 mA 12 mA 16 mA 20 mA
0
I
in
[mA]
Q [l/h]
1d
50 l/h
20 l/h
Q
select mA max. d
40 l/h
10 l/h
30 l/h
1e
Q
select mA max. e
Q
select mA min. d
Q
select mA min. e
I
in
[mA]
Q
select mA min. d
Q
select mA max. e
Q
select mA max. d
Q
select mA min. e
0 mA 4 mA 8 mA 12 mA 16 mA 20 mA
0
I
in/out
[mA]
Q [l/h]
L: Q
select mA min.
= ____ / ____mA
min.
H: Q
select mA max.
= ____ / ____mA
max.
Q
kal
L: Q
select mA min.
____/____ mA
min.
H: Q
select mA max.
____/____ mA
max.
Q
cal
Q [l/h]
I
in/out
[mA]
Note
For applications with high requirements in terms of
precision, the pressure control function must be used
with a pressure sensor.
Note
This menu item only appears if the pressure sensor
has already been detected once.