Rockwell Automation 1305 AC Drive, Firmware 1.01-3.00 User Manual - Manual (Page 35)

Chapter 2 – Installation/Wiring
2-19
OUTPUT DEVICES
Drive Output Disconnection
ATTENTION: Any disconnecting means wired
to 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, W. An auxiliary contact must be
used to simultaneously disable the drive or output
component damage may occur.
CABLE TERMINATION
Optional Cable Terminator
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
1600 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 inductor or
cable terminator. An inductor or terminator will help limit
reflection to the motor, to levels which are less than the motor
insulation value.
Table 2.D lists the maximum recommended cable length for
unterminated cables, since 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
The reactors listed in Catalog A111 can be used for the 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 output line reactors, it is recommended
that the drive PWM frequency be set to its lowest value to
minimize losses in the reactors.
IMPORTANT: 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 the motor torque.