246 Rockwell Automation Publication 520-UM001K-EN-E - August 2021
Appendix G Safe Torque Off Function
Example 3 – Safe-Torque-Off Connection with Coast-to-Stop Action
Using External +24V supply, SIL 3/PL e
Stop Category 0 – Coast
(1) Enclosure Recommended. External wiring failure modes must be considered as described in EN ISO 13849-2. Enclosure or
other measure to exclude these failure modes should be used.
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 &
23-24 & 33-34) will cause the output contact and Safe-Torque-Off Enable circuit
to trip and the motor 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.
PowerFlex 525 Certification
for Safe-Torque-Off
Certification information can be viewed at
rok.auto/certifications
.
Closed
Open
External +24V DC
24V DC COM
MSR127TP
Reset
+24V DC
PF 525
Stop
Start
COM
Gate control
power supply
Gate control
circuit
AC line
input power
S1
S2
X1 AUX
X2
A1 Coil
A2
External
contactor
100-C
100S-C
13 23 33
14 24 34
M
A1 S11 S52 S12 13 23 33 41
S21 S22 S34 A2 14 24 34 42
(1)
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