Allen-Bradley PowerFlex 525 User Manual page 215

Safe-Torque-Off Function Appendix G
Circuit Status
Circuit shown with guard door closed and system ready for normal drive
operation.
Operating Principle
This is a dual channel system with monitoring of the Safe-Torque-Off circuit and
drive. Opening the guard door will switch the input circuits (S11-S12 & S21-
S22) to the Minotaur monitoring safety relay unit. The output circuits (13-14)
will issue a Stop command to the drive and cause a controlled deceleration. After
the programmed delay, the timed output circuits (47-48 & 57-58) will cause the
Safe-Torque-Off Enable circuit to trip. If the motor is rotating when the trip
occurs, it will coast to stop. To restart the drive, the Minotaur safety relay must
first be reset followed by a valid start command to the drive.
Fault Detection
A single fault detected on the Minotaur safety input circuits will result in the
lock-out of the system at the next operation and will not cause loss of the safety
function.
A single fault detected on the PowerFlex 525 safety enable redundant inputs will
result in the lock-out of the drive and will not cause the loss of the safety
function.
Rockwell Automation Publication 520-UM001A-EN-E - February 2013 215