Rockwell Automation Allen-Bradley Kinetix 5500

Rockwell Automation Publication 2198-UM001M-EN-P - November 2022 159
Chapter 9 Kinetix 5500 Safe Torque Off - Hardwired Safety
Description of Operation The Safe Torque Off feature provides a method, with sufficiently low
probability of failure, to force the power-transistor control signals to a disabled
state. When disabled, or any time power is removed from the safety enable
inputs, all drive output-power transistors are released from the ON-state. This
results in a condition where the drive performs a Category 0 Stop. Disabling
the power transistor output does not provide mechanical isolation of the
electrical output that is required for some applications.
Under normal operation, the Safe Torque Off inputs are energized. If either of
the safety enable inputs are de-energized, then all output power transistors
turn off. The Safe Torque Off response time is less than 12 ms.
Figure 72 - System Operation when Inputs are Meeting Timing Requirements
ATTENTION: If there are two simultaneous faults in the IGBT circuit,
permanent magnet motors can result in a rotation of up to 180 electrical
degrees.
ATTENTION: If any of the safety enable inputs de-energize, the Start Inhibit
field indicates SafeTorqueOffInhibit and GuardStopRequestStatus bit of
AxisGuardStatus tag set to 1. Both inputs must be de-energized within 1
second and re-energized within 1 second to avoid GuardStopInputFault
conditions.
24V DC
24V DC
0V DC
0V DC
1
1
0
0
100 ms
1 Second
1
23 4
5
6
GuardStopRequestStatus
GuardStopInputFault
SS_IN_CH0
SS_IN_CH1
Event Description
1 At least one input is switched-off. GuardStopRequestStatus bit is set to 1.
2
Second input is switched-off within 1 second. This event must always occur before event 3 to prevent
GuardStopInputFault.
3 First input is switched-on.
4 Second input is switched-on within 1 second of event 3.
5
Both inputs are in OFF state simultaneously within 1 second. As a result, GuardStopInputFault is not
posted.
6
The GuardStopRequestStatus bit sets back to 0 if event 4 occurs within a 100 ms interval after event 3.
If event 4 is outside of the 100 ms interval, but within the 1 second interval after event 3, then the
GuardStop RequestStatus bit sets back to 0 after the 1 second interval following event 3 (not
immediately following event 4).