Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011 75
Detailed Drive Operation Chapter 1
Output Devices
Drive Output Disconnection
PowerFlex 700S Phase II drives can be used with an output contactor between the
drive and motor. This contactor can be opened under load without damage to the
drive. It is recommended, however, that the drive have a programmed “Enable”
input and that this input be opened at the same time as the output contactor. See
Digital Inputs
on page 37 for more information.
Cable Termination
Refer to the Wiring and Grounding Guidelines for Pulse Width Modulated
(PWM) AC Drives Installation Instructions, publication DRIVES-IN001
, for
detailed information.
Output Reactor
Bulletin 1321 Reactors can be used for drive input and output. These reactors are
specifically constructed to accommodate IGBT inverter applications with
switching frequencies up to 20 kHz. They have a UL approved dielectric strength
of 4000 volts, opposed to a normal rating of 2500 volts. The first two and last two
turns of each coil are triple insulated to guard against insulation breakdown
resulting from high dv/dt. When using motor line reactors, it is recommended
that the drive PWM frequency be set to its lowest value to minimize losses in the
reactors.
By using an output reactor the effective motor voltage will be lower because of the
voltage drop across the reactor - this may also mean a reduction of motor torque.
ATTENTION: Any disconnecting means wired to the drive output
terminals U, V and W must be capable of disabling the drive if opened
during drive operation. If opened during drive operation, the drive will
continue to produce output voltage between U, V, and W. An auxiliary
contact must be used to simultaneously disable the drive.
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