C-6 Application Notes
Torque Proving
When the drive receives a start command to begin a lifting operation, the
following actions occur:
1. The drive first performs a transistor diagnostic test to check for
phase-to-phase and phase-to-ground shorts. A failure status from
either of these tests will result in a drive fault and the brake relay will
NOT be energized (brake remains set).
2. The drive will then provide the motor with flux as well as perform a
check for current flow through all three motor phases. This ensures
that torque will be delivered to the load when the mechanical brake is
released. When torque proving is enabled, open phase loss detection
is performed regardless of the setting of Bit 12 of [Fault Config 1],
parameter 238.
3. If the drive passes all tests, the brake will be released and the drive
will take control of the load after the programmed time in [Brk
Release Time], parameter 604 which is the typical mechanical
release time of the brake.
Brake Proving
When the drive receives a stop command to end a lifting operation, the
following actions occur:
1. The brake is commanded closed when the speed of the motor reaches
zero.
2. After the time period programmed in [Brk Set Time], parameter 607,
the drive will verify if the brake is capable of holding torque. It will
do this by ramping the torque down at a rate set in [TorqLim
SlewRate], parameter 608. Note that the drive can be started again at
any time without waiting for either of the above timers to finish.
3. While the torque is ramping down, the drive will perform a brake slip
test. If movement exceeds the limit set in [BrkSlip Count], parameter
609, then an alarm is set and the drive will start a brake slip
procedure. The drive will allow the motor to travel the distance
programmed [Brk Alarm Travel], parameter 610. Another slip test
will be performed and will repeat continuously until; A) the load
stops slipping, or B) the load reaches the ground. This feature keeps
control of the load and returns it to the ground in a controlled manner
in the event of a mechanical brake failure.
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