Operating Modes; Control Modes - Grundfos CUE Series Installation And Operating Instructions Manual

7. Operating modes

The following operating modes are set on the control panel in
menu OPERATION, display 1.2. See section 10.5.2.
Operating mode Description
The pump is running in the control mode
Normal
selected
The pump has been stopped (green indicator
Stop
light is flashing)
Min. The pump is running at minimum speed
Max. The pump is running at maximum speed
Max.
Min. and max. curves.
The pump speed is kept at a given
set value for minimum and maximum
Min.
speed, respectively.
Example: Max. curve operation can for instance be used in
connection with venting the pump during installation.
Example: Min. curve operation can for instance be used in
periods with a very small flow requirement.

8. Control modes

The control mode is set on the control panel in menu
INSTALLATION, display 3.1. See section 10.7.1.
There are two basic control modes:
• Uncontrolled operation (open loop).
• Controlled operation (closed loop) with a sensor connected.
See sections 8.0.1 and 8.0.2.
8.0.1 Uncontrolled operation (open loop)
Constant curve.
The speed is kept at a set value in
the range between the min. and max.
curve.
The setpoint is set in %
corresponding to the required speed.
Example: Operation on constant curve can for instance be used
for pumps with no sensor connected.
Example: Typically used in connection with an overall control
system such as the MPC or another external controller.
8.0.2 Controlled operation (closed loop)
CUE
Δp
CUE
Δp
CUE
CUE
CUE
L
L
CUE
CUE
Proportional
differential
pressure.
The differential
pressure is reduced
at falling flow rate
and increased at
rising flow rate.
Constant
differential
pressure, pump.
The differential
pressure is kept
constant,
independently of
the flow rate.
Constant
differential
pressure, system.
The differential
pressure is kept
Δp
constant,
independently of
the flow rate.
Constant pressure.
The pressure is
kept constant,
independently of
p
the flow rate.
Constant pressure
with stop function.
The outlet pressure
is kept constant at
high flow rate. On/
p
off operation at low
flow rate.
Constant level.
CUE
The liquid level is
kept constant,
independently of
the flow rate.
Constant level with
stop function.
CUE
The liquid level is
kept constant at
high flow rate.
On/off operation at
low flow rate.
Constant flow rate.
The flow rate is
kept constant,
independently of
Q
the head.
Constant
temperature.
The liquid
temperature is kept
constant,
t
independently of
the flow rate.
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