Grundfos SP Installation And Operating Instructions Manual page 17

6.6.4 Connection in the case of unidentified cable marking/
connection
If it is unknown where the individual conductors are to be connected
to the mains in order to ensure the correct direction of rotation,
proceed as follows:
Motors wound for direct-on-line starting
Connect the pump to the mains as is expected to be right.
Then check the direction of rotation as described in section
Connection of three-phase motors.
Motors wound for star-delta starting
Determine the windings of the motor by means of an ohmmeter and
name the conductor sets for the individual windings accordingly:
U1-U2, V1-V2, W1-W2. See fig.
connection - motors wound for star-delta
U1 U2
V1 V2
Unidentified cable marking/connection - motors wound for star-
delta starting
If star-delta starting is required, connect the conductors as shown in
fig. Grundfos motors wound for star-delta
If direct-on-line starting is required, connect the conductors as
shown in fig. Grundfos motors wound for star-delta starting - direct-
on-line starting.
Then check the direction of rotation as described in section
Connection of three-phase motors.
Related information
6.6 Connection of three-phase motors
6.6.2 Motors wound for star-delta starting
6.6.5 Checking the direction of rotation
The pump must not be started until the suction
interconnector 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.
Unidentified cable marking/
starting.
W1 W2
starting.
During frequency converter operation, it is not advisable to
run the motor at a frequency higher than the rated
frequency (50 or 60 Hz). In connection with pump
operation, it is important never to reduce the frequency
(and consequently 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
installed.
If an MS motor with temperature transmitter is connected
to a frequency converter, a fuse incorporated in the
transmitter 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 × rated flow.
Voltage peaks for Grundfos submersible motors should be limited in
accordance with the table below.
Motor type
MS402
MS4000
MS6000 and MS6000P
MMS6
MMS8000
MMS10000
MMS12000
For asynchronous motors:
Permissible frequency ranges:
• 30-50 Hz
• 30-60 Hz.
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.
Max. U peak
Max. dU/dt
voltage
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
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