Rockwell Automation 20B PowerFlex 70, PowerFlex 700 Reference Manual - Manual (Page 123)

Output Current
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013 123
Output Current
[Output Current]
This parameter displays the total output current of the drive. The current value
displayed here is the vector sum of both torque producing and flux producing
current components.
Output Devices Drive Output Contactor
Also see Input Devices on page 108 .
Cable Termination
Voltage doubling at motor terminals, known as reflected wave phenomenon,
standing wave or transmission line effect, can occur when using drives with long
motor cables.
Inverter duty motors with phase-to-phase insulation ratings of 1200 volts or
higher should be used to minimize effects of reflected wave on motor insulation
life.
Applications with non-inverter duty motors or any motor with exceptionally long
leads may require an output filter or cable terminator. A filter or terminator will
help limit reflection to the motor, to levels which are less than the motor
insulation rating.
Cable length restrictions for unterminated cables are discussed on page 61 .
Remember that the voltage doubling phenomenon occurs at different lengths for
different drive ratings. If your installation requires longer motor cable lengths, a
reactor or cable terminator is recommended.
Optional 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
!
ATTENTION: To guard against drive damage when using output
contactors, the following information must be read and understood.
One or more output contactors may be installed between the drive and
motor(s) for the purpose of disconnecting or isolating certain motors/
loads. If a contactor is opened while the drive is operating, power will be
removed from the respective motor, but the drive will continue to
produce voltage at the output terminals. In addition, reconnecting a
motor to an active drive (by closing the contactor) could produce
excessive current that may cause the drive to fault. If any of these
conditions are determined to be undesirable or unsafe, an auxiliary
contact on the output contactor should be wired to a drive digital input
that is programmed as “Enable.” This will cause the drive to execute a
coast-to-stop (cease output) whenever an output contactor is opened.