Rockwell Automation Publication 750-IN118A-EN-P - May 2021 109
Chapter 4 Power Wiring
Output Contactor Precaution
If your product includes a configured output bay with an output contactor, the
following precaution applies to that output contactor.
If you supplied an output contactor between the PowerFlex 755T Drives
Configured to Order Program product and the motor, the following
precaution applies to that output contactor.
ATTENTION: A contactor or other device that routinely disconnects and
reapplies the AC line to the drive to start and stop the motor can cause drive
hardware damage. The drive is designed to use control input signals that
start and stop the motor. If an input device is used, operation must not
exceed one cycle every 3 minutes or drive damage will occur.
ATTENTION: The drive start/stop/enable control circuitry includes solid-
state components. If hazards due to accidental contact with moving
machinery or unintentional flow of liquid, gas or solids exist, an additional
hardwired stop circuit may be required to remove the AC line to the drive. An
auxiliary braking method may be required.
ATTENTION: An auxiliary contact on the output contactor is wired to a drive
digital input that is programmed as “Enable.” This causes the drive to execute
a coast-to-stop (cease output) whenever the output contactor is opened. This
is a safety measure to guard against damage to the drive.
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 one or more motors for
the purpose of disconnecting or isolating certain motors/loads. If a
contactor is opened while the drive is operating, power is removed from the
respective motor, but the drive continues 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 causes the drive to
execute a coast-to-stop (cease output) whenever an output contactor is
opened.
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