Grundfos SP Serie Instrucciones De Instalación Y Funcionamiento página 18

6.6.5 Checking the direction of rotation
The pump must not be started until the suction intercon-
nector has been completely submerged in the liquid.
When the pump has been connected to the power supply, check the
direction of rotation:
1. Start the pump and measure quantity of water and head.
2. Stop the pump and interchange two phases.
3. Start the pump and measure quantity of water and head.
4. Stop the pump.
5. Compare the two results. The connection giving the larger
quantity of water and the higher head is the correct one.
6.6.6 Soft starter
Grundfos only recommends the use of soft starters which control
the voltage on all three phases and which are provided with a
bypass switch.
Ramp times: Maximum 3 seconds.
For further details, contact your soft starter supplier or Grundfos.
6.6.7 Frequency converter operation
Three-phase MS motors can be connected to a frequency
converter.
During frequency converter operation, it is not advisable to
run the motor at a frequency higher than the rated fre-
quency (50 or 60 Hz). In connection with pump operation,
it is important never to reduce the frequency (and conse-
quently the speed) to such a level that the necessary flow
of cooling liquid past the motor is no longer ensured.
To enable the monitoring of the motor temperature,
Grundfos recommend that Pt100 or Pt1000 sensor is in-
stalled.
If an MS motor with temperature transmitter is connected
to a frequency converter, a fuse incorporated in the trans-
mitter will melt and the transmitter will be inactive. The
transmitter cannot be reactivated. This means that the
motor will operate like a motor without a temperature
transmitter.
To avoid damage to the pump part, make sure that the motor stops
when the pump flow falls below 0.1 x rated flow.
Voltage peaks for Grundfos submersible motors should be limited in
accordance with the table below.
Max. U peak volt-
Motor type
MS402
MS4000
MS6000 and MS6000P
MMS6
MMS8000
MMS10000
MMS12000
For asynchronous motors:
Permissible frequency ranges:
• 30-50 Hz
• 30 60 Hz.
18
Max. dU/dt
age
650 V
2000 V/μs
phase-phase
850 V
2000 V/μs
phase-phase
850 V
2000 V/μs
phase-phase
850 V
500 V/μs
phase-ground
850 V
500 V/μs
phase-ground
850 V
500 V/μs
phase-ground
850 V
500 V/μs
phase-ground
Ramp times: Maximum 3 seconds from standstill to minimum
frequency and vice versa
For synchronous motors MS6000P:
Permissible frequency ranges:
• 55-100 Hz
• 55-120 Hz.
Ramp times: Maximum 3 seconds from standstill to minimum
frequency and vice versa
Depending on the type, the frequency converter may cause
increased acoustic noise from the motor. Furthermore, it may
expose the motor to detrimental voltage peaks. This can be abated
by installing an LC filter or even better a sinus filter between the
frequency converter and the motor.
For further details, contact your frequency converter supplier or
Grundfos.