Product Manual

SP introduction
SQ, SQE, CU 331, and SP
12
62
Overtemperature protection
Accessories for protection against overtemperature
are available for both Grundfos MS and MMS
submersible motors. When the temperature becomes
too high, the protection device will cut out so damage
to the pump and motor can be avoided.
Restart of the motor after cut-out can be achieved in
two ways:
• manual restart
• automatic restart.
Automatic restart means that the MP 204 attempts to
restart the motor after 15 minutes. If the first attempt is
not successful, restarting will be reattempted at
30-minute intervals.
MS: The Grundfos MS submersible motors (with the
exception of MS 402) are available with a built-in
Tempcon temperature transmitter for protection
against overtemperature. By means of the transmitter,
it is possible to read out and/or monitor the motor
temperature via an MP 204 or a PR 5714 relay.
The Grundfos MS 6000C submersible motors can be
fitted with a Pt100. The Pt100 is fitted in the motor and
connected directly to the MP 204 or monitored by the
PR 5714 relay.
MMS: For the protection of the Grundfos MMS
submersible motors against overtemperature,
Grundfos offers the Pt100 temperature sensor as an
optional extra.
The Pt100 is fitted in the motor and connected directly
to the MP 204 or monitored by the PR 5714 relay.
Protection against upthrust
In case of a very low counter pressure in connection
with start-up, there is a risk that the entire chamber
stack may rise. This is called upthrust. Upthrust may
damage both pump and motor. Grundfos pumps and
motors are protected against upthrust as standard,
preventing upthrust from occurring during the critical
start-up phase. The protection consists of either a
built-in stop ring or hydraulic balancing.
Built-in cooling chambers
In all Grundfos MS submersible motors, efficient
cooling is ensured by cooling chambers at the top and
at the bottom of the motor, and by an internal
circulation of motor liquid. See fig. 59.
As long as the required flow velocity past the motor is
maintained, cooling of the motor will be efficient.
Lightning protection
The smallest Grundfos submersible motors, such as
the MS 402, are all insulated in order to minimize the
risk of motor burnout caused by lightning strike.
Fig. 59 MS 4000
Reduced risk of short-circuit
The embedded stator winding in the Grundfos MS
submersible motor is hermetically enclosed in
stainless steel. The result is high mechanical stability
and optimum cooling. Also, this eliminates the risk of
short-circuit of the windings caused by water
condensation.
TM00 5698 0996