Keep the manual for future reference – For more informations visit www.saerelettropompe.com
39
The amperometric protection on the single phase of the motor must be set at a value equal to 0.58 x the value of the rated current.
STARTING WITH IMPEDANCES OR AUTOTRANSFORMER
It can be used for motors of any power.
ATTENTION!
·
Starting voltage (Us): ≥ 65% rated voltage (Un).
·
The duration of the starting phase must not exceed 2,5 s
STARTING WITH SOFT STARTER
It can be used for motors of any power.
ATTENTION!
·
Starting voltage (Us): ≥ 50% rated voltage (Un)
·
The duration of the starting and stopping phases must not exceed 6 s
·
Starting current (Is) ≤ 350% rated current (In)
STARTING WITH VARIABLE FREQUENCY DRIVE (VFD-INVERTER)
Motor configuration
SAER motors can be used in the standard version with VFD in the following conditions:
-
Power (Pn) ≤55kW or frame size up to 250
-
Voltage (Un) ≤500V
For motors that do not fall into these categories, a special version for operation with VFD must be requested when ordering.
Insulated bearings: for motors with frame size 280 or higher, the NDE bearing must be of insulated type.
Limits on frequency of use
Maximum frequency: The maximum operating frequency must never exceed the rated frequency of the motor.
Frequency below the rated frequency: for operation at frequencies below the rated frequency, check that, with the speed reduction, there is a
sufficient load reduction to prevent the motor from overheating (note: centrifugal pumps and fans do not require this verification).
Resonance phenomena
Avoid operation at frequencies that induce resonance phenomena and high vibration values. The transition between these frequencies must
be done quickly.
Start/Stop
Start/Stop ramp: The ramp must have an indicative maximum duration of 6 seconds (from start to minimum frequency and vice versa). If
present, activate the extra torque function (Torque boost) in starting.
Number of starts/hour: the number of starts/hour of the motor must be respected. Refer to paragraph 4.
Switching frequency
The switching frequency can usually be adjusted between 2 and 12 kHz. A high switching frequency reduces the noise of the inverter but
causes high voltage peaks that damage the motor. It is recommended to set the switching frequency to values between 3 and 5 kHz.
Filters
Filters and cable length: refer to the tables with the maximum permissible cable lengths in the documentation of the drives. If they are not
present, contact SAER Technical Assistance
Du/dt filter: du/dt filters limit the output voltage peaks and thus make the motor life longer. Their application is necessary depending on the
inverter (brand and type), the length of the cable, the motor power supply voltage and other factors. In addition, these filters limit capacitive
leakage currents and high frequency emissions from the motor cables. Refer to the drive documentation for more information.
EMC
Make the ground connections and the other electrical connections properly and to ensure compliance with EMC (Electromagnetic
Compatibility) requirements. Use shielded type cables where necessary.
5.10 GROUND CONNECTION
·
Choose a ground cable with copper conductor of adequate section (TAB.X), refer to the local and national
regulations of the electrical system of the place where the pump is installed. If in doubt, use a ground cable
with a copper conductor having the same cross-section as that of the phase conductors that power the motor.
ü
Check that the ground cable is connected to the motor in the proper position.
·
For aggressive environments where there is a risk of corrosion of the conductor or of the ground connection,
provide for a special protection system (for example by means of an appropriately adjusted differential switch)
which intervenes even if the ground conductor is no longer connected.
