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6. VFD continued.
PD WATER SYSTEMS suggests these MAX values for three phase encapsulated submersible motors
Max. Vpeak voltage: 1000 V phase-phase
Max. dV/dt :2000 V/μs
Filters are usually applied when the power cable to the motor is longer than 50ft (15.2m)
PD WATER SYSTEMS suggests the use of an input filter when the VFD is used in a residential area, to protect other
devices connected to the same mains from noise caused by the VFD
Frequency range: 30 Hz – 60 Hz
Drive carrier frequency: The range must be from 4.5k to 5k Hz .
Higher values will increase the quantity of Voltage Spikes x per second and reduce motor insulation lifetime.
Lower values give a poor shape to the power curve.
Ramp-up time / Ramp down time: | df/dt | > 30 Hz/sec (where f indicates the frequency) to ensure the life of the
thrust bearings
The motor's operating speed must always operate so the minimum cooling flows are reached.
0.50 ft/sec for 6-inch motors
0.98 ft/sec for 4-inch motors
Motor overload protection must trip within a time equal to or faster than how indicated by Class 10 overload curve
and must trip within 115% of the nameplate Max. Amp.
PEARL's encapsulated submersible motors are not declared inverter duty motors by NEMA MG1
standards. The reason is NEMA MG1 standard part 31 does not include a section covering
encapsulated winding designs.
PEARL's submersible motors can be used with VFDs without problems or warranty concerns providing
all PD WATER SYSTEMS guidelines are followed.
PEARL's single-phase, 2- and 3-wire, encapsulated submersible motors hould only be used with the
appropriate variable speed drive.
7. INSTALLATION
Before installing the motor, read both the motor and pump instructions manuals.
Keep both manuals an a safe place.
If the product shows any signs of damage, do not proceed with installation and call your local
stockest / distributor.
You must use suitable equipment and protective devices. Observe all accident prevention regulations.
Installations must always e in accordance with current local and/or national regulations, legislation and bylaws
governing installation of water and power equipment.
PEARL submersible motors are designed to be used in a shaft up vertical position.
During acceleration, the pump thrust increases as its output head increases. In cases where the pump head stays
below its normal operating range during startup and full speed condition, the pump may create upward thrust. This
creates upward thrust on the motor upthrust bearing. This is an acceptable operation for short periods at each start,
but running continuously with upthrust will cause excessive wear on the upthrust bearing.
4MWP
4" Submersible Motors
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