External Setpoint Signal; Operation With Sensor Feedback - Grundfos CRE Series Installation And Operating Instructions Manual

11. External setpoint signal

It is possible to remotely set the setpoint by connecting an analog
signal to the analog input terminals. The external signal may be
0.5 - 3.5 V, 0-5 V, 0-10 V, 0-20 mA or 4-20 mA.

11.1 Operation with sensor feedback

If fitted with a sensor, the pump can operate according to the
control modes below:
• Constant pressure
• Constant differential pressure
• Constant temperature
• Constant differential temperature
• Constant flow rate
• Constant level
• Constant other value.
If operation with sensor feedback is selected, the setpoint can be
set externally within the range from the lower value of the sensor
measuring range to the setpoint.
Example
Setpoint is to be the upper limit of the pressure sensor range.
Operating mode is to be normal.
Control mode is to be constant pressure.
Operating range to be 25-100 %.
Analog input to be set as follows: (Grundfos GO).
(Analog input 2) Terminals 7 and 23.
External setpoint function to be set as follows: (Grundfos GO).
See fig. 37.
Actual setpoint
Upper value of sensor
measuring range
Setpoint set on motor, with the
R100 or with Grundfos GO
Remote
Actual
setpoint
Lower value of sensor
measuring range
0.5 3.5 V
0 5V
0 10 V
0 20 mA
4 20 mA
Fig. 37 Relation between the actual setpoint and the external
setpoint signal in operation with sensor feedback
Example: At a sensor value of 0 psi, a setpoint set of 50 psi
min
and an external setpoint of 80 % (an 8 V analog signal if using an
analog signal of 0-10 V), the actual setpoint will be as follows:
Actual
= (setpoint - sensor
min
setpoint
= (50 - 0) x 80 % + 0
= 40 psi
External setpoint signal
) x % sensor
external setpoint + min
33