Functions
Grundfos CUE
24
Operating range
The area between the min. and max. speed is the
actual operating range of the pump.
The operating range can be changed by the user within
the
area defined by the pump-dependent speed range.
For some pump families over synchronous operation
(max.
speed above 100%) will be possible. This
requires an over-size motor to deliver the shaft power
required by the pump during over-synchronous opera-
tion.
Fig. 27 Setting of the min. and max. speed in % of the
nominal speed of the pump
Fig. 28 Operating range of the CUE
Motor bearing monitoring
This function is used to give an indication when it is time
to relubricate or change the motor bearings.
It shows these pieces of information:
• When to relubricate the motor bearings.
• How many times relubrication has been confirmed,
• When to replace the motor bearings.
Default function
The default function is based on the "mileage" of the
pump an
d takes into account if the pump has been run-
ning with reduced speed.
Extended function
The bearing temperature is also included in the calcu-
lation.
The extended function requires an MCB 114 sensor
inpu
t module and Pt100/Pt1000 sensors measuring the
bearing temperature.
Monitoring of motor bearing temperatures
When temperature sensor 1 and 2 are used for meas-
uring the motor bearing temperature, a warning or an
alar
m will be generated if the bearing temperature gets
too high.
Warnings and alarms are generated and reset using
hyste
resis. See fig. 29.
Fig. 29 Monitoring of bearing temperature with warning
and alarm limits
Standstill heating
This function pre-heats the motor during standstill in
order to avoid condensation within the motor.
When the pump is stopped by a stop command, a cur-
rent will be applied to the motor windings in order to
keep
the temperature within the motor above the dew-
point temperature. No external heater is needed.
The pre-heating of the motor is especially important
w
hen the motor is installed under these conditions:
• high humidity
• outdoor installation.
The consequences of condensed moisture within the
moto
r are for example corrosion damage to electrical
contacts and the bearings of the motor shaft.
TM00 7747 1896
Actual operation
speed range
Min. Max.
Pump-dependent speed range
Min.
Nom.
Max.
100%
Speed [%]
Min. speed adj. range
Max. speed adj. range
100 %
Max. curve
Pump-dependent
min. performance
Min. curve
Operating range
TM04 0371 0608
Warning limit
Alarm limit
Temperature
248 °F
(120 °C)
239 °F
(115 °C)
212° F
(100 °C)
203 °F
(95 °C)
Normal
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