Grundfos CRE User Manual

8.13 "External setpoint function"
Pump variant
"External setpoint
function"
CME ●
CRE, CRIE, CRNE, CRKE, SPKE,
MTRE
●
You can influence the setpoint by an external signal, either via one
of the analog inputs or, if an advanced functional module (FM 300)
is fitted, via one of the Pt100/1000 inputs.
Before you can enable the function, you must set one of
the analog inputs or Pt100/1000 inputs to "External
setpoint function".
See the sections on analog inputs and Pt100/1000 inputs.
Example with constant pressure with linear influence
Actual setpoint: actual input signal x (setpoint - sensor min.) +
sensor min.
At a sensor minimum of 0 psi, a setpoint of 232 psi and an external
setpoint of 60 %, the actual setpoint is 0.60 x (232 - 0) + 0 = 139
psi. See the figure below.
A
B
C
D
E
F
TM080912
Example of setpoint influence with sensor feed back
Pos. Description
A Sensor maximum
B "Setpoint"
C Actual setpoint
D Sensor minimum
E
Actual input signal
(60 %)
F External setpoint signal
Example with constant curve with linear influence
Actual setpoint: actual input signal x (setpoint - user-set minimum
speed) + user-set minimum speed.
At a user-set minimum speed of 25 %, and a setpoint of 85 % and
an external setpoint of 60 %, the actual setpoint is 0.60 x (85 - 25) +
25 = 61 %. See the figure below.
100
0
100 %0
3.5 V0.5
5 V0
10 V
0
20 mA
0
20 mA4
-50 204 C
25
61
85
A
B
C
D
E
F
G
TM080913
Example of setpoint influence with constant curve
Pos. Description
A Speed [%]
B "Setpoint"
C Actual setpoint
D User-set min. speed
E Fixed maximum speed
F
Actual input signal
(60 %)
G External setpoint signal
Related information
8.5 "Analog inputs"
8.6 "Pt100/1000 inputs"
45
English (US)

Grundfos CRE Specifications

General

Protection Class	IP55
Material	Stainless Steel
Applications	Water supply, pressure boosting, irrigation
Impeller Material	Stainless Steel
Pump Housing Material	Stainless Steel
Connection Size	DN32 to DN200 (depending on model)
Power Supply	3-phase
Control	Integrated frequency converter