Product Manual

SQ, SQE introduction
SQ, SQE, CU 331, and SP
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Wear resistance
The pump design features "floating" impellers (not
fastened to the shaft). Each impeller has its own
tungsten carbide/ceramic bearing. The construction
and materials ensure high wear resistance to sand for
long product life.
Fig. 3 Example of Grundfos floating impeller
Protection against upthrust
Starting up a pump with a very low counter pressure
involves the risk of the entire impeller stack being
lifted, also called upthrust. Upthrust may cause
breakdown of both pump and motor.
SQ, SQE motors are fitted with a top bearing
protecting both pump and motor against upthrust, thus
preventing breakdown during the critical start-up
phase.
Excellent starting capabilities
The integrated electronic unit of the motor features soft
starting. Soft start reduces the starting current and
thus gives the pump a smooth and steady
acceleration.
The soft starter minimizes the risk of wear on the pump
and prevents overloading of the mains during start-up.
The excellent starting capabilities are a result of the
high locked-rotor torque of the permanent magnet
motor together with the few pump stages. The high
starting reliability also applies in case of low voltage
supply.
Fig. 4 Soft-start feature
Overvoltage and undervoltage protection
Overvoltage and undervoltage may occur in case of
unstable voltage supply.
The integrated protection of all motors prevents
damage to the motor in case the voltage moves
outside the permissible voltage range.
The pump will cut out if the voltage falls below 150 V or
rises above 315 V. The motor is automatically cut in
again when the voltage again falls within the
permissible voltage range. Therefore no extra
protection relay is needed.
Overload protection
Exposure of the pump to heavy load causes the
current consumption to rise. The motor will
automatically compensate for this by reducing the
speed to 3000 rpm. Further overload will lead to stop.
If the rotor is being prevented from rotating, this will
automatically be detected and the power supply will be
cut out. Consequently, no extra motor protection is
needed.
Overtemperature protection
A permanent magnet motor gives off very little heat to
its surroundings. In combination with an efficient
internal circulation system leading the heat away from
the rotor, stator and bearings, this ensures optimum
operating conditions for the motor.
As an extra protection, the electronic unit has a built-in
temperature sensor. When the temperature rises too
high, the motor is cut out; when the temperature has
dropped, the motor is automatically cut in again.
Reliability
The motors are built for high reliability and feature:
• Tungsten carbide / ceramic bearings
• thrust bearings protecting against downthrust
• product life time equal to conventional AC motors.
Variable speed
The SQE motor enables continuously variable speed
control from 3,000 to 10,700 rpm. The pump can be set
to operate in any duty point in the range between the
3,000 and 10,700 rpm performance curves of the
pump. Consequently, the pump performance can be
adapted to any specific requirement.
The variable speed control facility requires the use of
the CU 300 or CU 301 control unit.
For the calculation of pump speed, the program "SQE
Speed Calculation" is available on CD-ROM as an
accessory.
TM01 3141 3498TM01 3479 4198
Current [A]
DOL (direct-on-line starting)
Soft start
3Time [s]