104 Rockwell Automation Publication 750-RM100A-EN-P - August 2019
Chapter 11 Application References
Bus Regulation
When you use a PowerFlex 755T drive in a lifting application, a PowerFlex
755TR drive is used to allow full line regeneration capabilities. You do not need
to use a dynamic braking resistor in this configuration. The PowerFlex 755TL
drive is not recommended for lifting applications. Typical bus regulation
parameter settings that are associated with regeneration are:
• 10/11:229 [Regen Power Lmt] = -200%
• 10/11:116 [Bus Reg Mode A] = Disabled
Brake Proving Configuration
By default, the drive is testing for brake slip only during Brake Slip Test Step 7
(see Brake Slip Test
on page 102). If the brake fails while the drive is stopped, the
load can suddenly drop to the floor. To have the drive monitor for brake slip
while the drive is stopped, set 9:50 [Trq Prove Cfg] bit 6 ‘BrkSlipStart’. With this
bit set, if the drive detects a brake slip while the drive is stopped, the drive starts
up and takes control of the load, goes into a brake slip test, and lowers the load to
the floor. When the drive detects a brake slip in this manner (from a stopped
state), the drive allows one start after the load reaches a safe position to move the
load. After this point, the drive enunciates a Brake Slipped alarm and a power
cycle is required to restart the drive.
If the drive is set up for encoderless torque proving, there is no brake slip test.
After stopping, the drive engages the brake when the motor speed falls below the
setting in 9:70 [Float Tolerance].
Tuning the Motor for Torque Prove Applications
It is important that you enter all motor data correctly. When using PowerFlex
755T Autotune features, it is recommended to disconnect the motor from the
hoist/crane equipment during the tests. It is recommended that Parameter 10 of
the I/O card that is wired to the brake control is set to 10/11:354 [Motor Side Sts
1] Bit 1, so that the brake releases when the motor starts to run.
Torque Proving is only supported on induction motors. PowerFlex 755T motor
control modes Induction Sensorless Vector (SV) and Induction Flux Vector (FV)
are supported.
ATTENTION: To guard against personal injury and/or equipment damage due
to an unexpected brake release, verify that the digital output that is used for
brake connections and/or programming. The PowerFlex 755T drive does not
control the mechanical brake until TorqProve is enabled
. If the brake is
connected to a digital output, it could be released. If necessary, disconnect the
digital output until wiring/programming can be completed and
verified.
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