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

8.3 Operating modes

The following operating modes are set on the operating panel
using the [Favourites] menu.
Operating mode Description
The pump is running in the operating mode
Normal
selected
The pump has been stopped, and the green
Stop
indicator light is flashing
Min. The pump is running at minimum speed
Max. The pump is running at maximum speed
User curve The pump is running at user-defined speed
Max.
Minimum and maximum curves.
The pump speed is kept at a given set value
Min.
for minimum and maximum speed.
Example: Maximum curve operation can for instance be used in
connection with venting the pump during installation.
Example: Minimum curve operation can for instance be used in
periods with a very small flow rate requirement.

8.4 Control modes

The control mode is set in the [Favourites] menu.
There are two basic control modes:
• Uncontrolled operation (open loop).
• Controlled operation (closed loop) with a sensor connected.
See sections 8.4.1 Uncontrolled operation (open loop)
8.4.2 Controlled operation (closed
8.4.1 Uncontrolled operation (open loop)
Constant curve.
The speed is kept at a set value in the
range between the minimum and maximum
curves.
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 MPC or another external controller.
8.4.2 Controlled operation (closed loop)
CUE
Δp
CUE
Δp
and
loop).
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
CUE
pressure, system.
The differential
pressure is kept
Δp constant,
independently of
the flow rate.
Constant pressure.
CUE
The pressure is
kept constant,
independently of
p
the flow rate.
Constant pressure
with stop function.
CUE
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
L kept constant,
independently of
the flow rate.
Constant level with
stop function.
CUE
The liquid level is
kept constant at
L
high flow rate.
On/off operation at
low flow rate.
Constant flow rate.
CUE
The flow rate is
kept constant,
independently of
Q
the head.
Constant
temperature.
CUE
The liquid
temperature is kept
constant,
t
independently of
the flow rate.
21