Grundfos MS 4000, Руководство по эксплуатации продукта

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39
Control functions
This table describes the protection provided by CU 3.
Control
parameters Function Problem Advantages
Ground failure Insulation resistance is measured only
when motor is not operating.
A high-impedance voltage is applied to the
motor leads and leakage to ground is
measured. If the factory-set value is
higher than the one measured the motor
cannot be started.
Damaged or decom-
posed insulation in
motor, cable or cable
joint. Possibility of failure
indication on motor,
cable and cable joint,
service indication.
Temperature The actual motor temperature is measured
by means of the Pt100. Via a relay, the
signal is sent to the CU 3 where the
measured temperature is compared with
the factory-set value. Temperature protec-
tion requires a submersible motor with a
Pt100. Overload, frequen start
s/stops, operation
against blocked
discharge pipe, insuffi-
cient flow velocity past
the motor. Longer motor life, safe
operating conditions,
service indication.
Overvoltage/
undervoltage If the factory-set values are exceeded, a
fault indication is given. If the CU 3
receives a temperature signal, the voltage
is no longer monitored, but the motor will
continue to run.
Therefore, the motor and consequently
the pump operation will be affected by
voltage variations critical to the life of the
motor.
If there is no temperature signal, the motor
will be stopped in case of overvoltage/
undervoltage.
The installation is close
to a transformer, the
mains do not absorb
load variations. Important installation
parameter, possibility
of improving operating
conditions.
Overload The motor power input is measured on
each of the three phases. The registered
power input is average of these three
values. If the factory-set value is
exceeded, the motor will stop. Incorrect dimensioning
of pump/motor, voltage
supply failure, defective
cable, blocking, wear or
corrosion. Longer pump lift,
safe operating
conditions, service indi-
cation.
Dry running The motor power input is measured on
each of the three phases. The registered
power input is an average of these three
values.
If the average value is lower than the
factory-setting value, the motor will stop.
Pump exposed to dry
running or underload,
for example caused by
wear. Traditional dry-running
protection is no longer
necessary, no extra
cables.
Current unbalance The power input of the motor is measured
on each of the three phases. Mains load is uneven,
incipient motor defect,
phase voltages diver-
ging. Motor protection
against overload,
service indication.
Phase sequence CU 3 and motor are installed so that the
phase sequence corresponds to correct
direction of rotation.
CU 3 monitors changes in the phase
sequences.
Two phases are
wrongly connected. Ensures correct pump
performance.
Accessories
MS Motors
MS.book Page 39 Wednesday, January 26, 2005 3:25 PM