Eaton PowerXL DH1 - Chapter 5-Motor And Application; Motor Selection; Connecting Motors in Parallel

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Chapter 5—Motor and application
POWERXL SERIES VFD MN040002EN—February 2018 www.eaton.com
Chapter 5—Motor and application
ote: N All following information is strongly recommended
but is not necessary if sufficient system design and
validation has been completed.
Motor selection
General recommendations for motor selection:
•
Use three-phase powered asynchronous motors
with short-circuit rotors and surface cooling, also
called inverter motors or standard motors for the
frequency-controlled drive system (PDS). Other
specifications such as external rotor motors, slip-ring
motors, reluctance motors, synchronous or servo motors
can also be run with a frequency inverter, but normally
require additional planning and discussion with the
motormanufacturer
•
Use only motors with at least heat class F (311°F [155 °C]
maximum steady state temperature)
•
Four-pole motors are preferred (synchronous speed: 1500
min
–1
at 50 Hz or 1800 min
–1
at 60 Hz)
•
Take the operating conditions into account for S1
operation (IEC 60034-1)
•
When operating multiple motors in parallel on one
frequency inverter, the motor output should not be more
than three power classes apart
•
Ensure that the motor is not over-dimensioned. If a motor
in speed control mode is under-dimensioned, the motor
rating must only be one rating level lower
Connecting motors in parallel
The PowerXL frequency inverters allow parallel operation of
several motors using multi-pump application control mode:
•
Multi-pump application: several motors with the same
or different rated operational data. The sum of all motor
currents must be less than the frequency inverter’s rated
operational current
•
Multi-pump application: parallel control of several motors.
The sum of the motor currents plus the motors’ inrush
currents must be less than the frequency inverter’s rated
operational current
Parallel operation at different motor speeds can be
implemented only by changing the number of pole pairs
and/or changing the motor’s transmission ratio.
CAUTION
Debounced inputs may not be used in the safety
circuitdiagram.
If you are connecting multiple motors on one frequency
inverter, you must design the contactors for the individual
motors according to utilization category AC-3.
Selecting the motor contactor is done according to the rated
operational current of the motor to be connected.