Connecting Motors In Parallel - Eaton PowerXL DC1 20 Series Installation Manual

2.10.4 Connecting Motors in Parallel

￫
If multiple motors are connected in parallel, the total of their
motor currents must be lower than the DC1 variable frequency
drive's rated operational current.
Connecting motors in parallel will reduce the load resistance at the variable
frequency drive's output. This will cause the total stator inductance to
decrease and the cables' stray capacitance to increase, resulting in greater
harmonic distortion when compared to a single-motor circuit.
In order to reduce the amount of current distortion, it is recommended to use
a motor choke or a sine filter at the variable frequency drive's output when
there are three motors or more.
￫
When running multiple motors in parallel with a single variable
frequency drive, the individual motors' outputs should not be
more than three output classes apart.
￫
If several motors are being run in parallel, you will not be able to
use the variable frequency drive's electronic motor protection.
As a result, each individual motor must be protected with
thermistors and/or an overload relay.Within a frequency range of
20 to 120 Hz, the PKE electronic motor-protective circuit-
breaker can be used for motor protection at a DC1 variable
frequency drive's output as well.
NOTICE
If multiple motors are being run simultaneously using a single
variable frequency drive, make sure to size the individual
motors' contactors as required for utilization category AC-3.
The motor contactors must be selected according to the rated
operational currents of the motors that will be connected.
￫
The total of the motor currents in operation, plus, for example,
the inrush current of a motor being added, must be less than
the rated operational current of the variable frequency drive.
In applications with motors that will be connected and
disconnected, we recommend using a motor choke or a sine
filter.
￫
Connecting multiple motors in parallel requires for the variable
frequency drive to modulate the output voltage with V/Hz
control. In order to meet this requirement, parameter P-60 on
DC1-...E1 variable frequency drives needs to be set to a value of
1 (= default setting).
DC1...20... and DC1...OE1 Variable Frequency Drives 02/20 MN040059EN www.eaton.com
2 Engineering
2.10 Switching to the output side
53