356 Rockwell Automation Publication 750-PM001N-EN-P - February 2017
Chapter 6 Troubleshooting
PowerFlex 755 Lifting/
Torque Proving
Review the Attention statement that follows if you intend to use the TorqProve™
feature without an encoder. TorqProve only applies to PowerFlex 755 drives.
For more information on TorqProve applications, refer to Appendix
C on page
439
.
External Brake Resistor
Figure 4 - External Brake Resistor Circuitry
This circuit is designed to remove input voltage to the drive if the line voltage is
high and forces dynamic braking to operate continuously.
ATTENTION: You must read the following information before you can use
TorqProve with no encoder.
Encoderless TorqProve must be limited to lifting applications where personal safety
is not a concern. Encoders offer additional protection and must be used where
personal safety is a concern. Encoderless TorqProve cannot hold a load at zero speed
without a mechanical brake and does not offer additional protection if the brake
slips/fails. Loss of control in suspended load applications can cause personal injury
and/or equipment damage.
It is your responsibility to configure drive parameters, test any lifting functionality
and meet safety requirements in accordance with all applicable codes and
standards. If encoderless TorqProve is desired, you must certify the safety of the
application. To acknowledge that you have read this “Attention” and properly
certified their encoderless application, bit 3 (“EnclsTrqProv”) of [Mtr Options Cfg],
parameter 40 must be changed to a “1.” This action removes Alarm 28, “TP Encls
Config” and allow bit 1 of Parameter 1100 to be changed to a “1” enabling
encoderless TorqProve.
ATTENTION: The drive does not offer protection for externally mounted brake
resistors. A risk of fire exists if external braking resistors are not protected.
External resistor packages must be self-protected from over temperature or a
circuit equivalent to the one shown here must be supplied.
Power On
R (L1)
S (L2)
T (L3)
Power Source DB Resistor Thermostat
Power O
M
M
(Input Contactor) M
Three-Phase
AC Input
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