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Rockwell Automation Publication PFLEX-UM003D-EN-P - June 2021
Description of Operation
Example 2 - Safe Torque Off Connection with Time Controlled Stop Action, Dual
Channel
Figure 11 - Stop Category 1 - Time Controlled
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 and S21…S22) to the
Minotaur monitoring safety relay unit. The output circuits (13…14) issue a Stop
command to the drive and cause a controlled deceleration. After the programmed
delay, the timed output circuits (47…48 and 57…58) will cause the Safe Torque Off
option and the drive 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. If
the Safe Torque Off option sticks On, the motor will stop on command due to the
enable input. The system cannot be reset when this fault condition exists.
The function is considered Safe Stop 1 time controlled (SS1-t per IEC 61800-5-2;
4.2.3.3). The controlled deceleration can fail undetected. The safety function will only
guarantee a coast to stop after the programmed delay. This function cannot be used
if a failure to initiate a controlled deceleration can cause a hazard in the final
application.
+24V DC
Common
+24V DC
GuardMaster
Trojan
Stop
Start
A1
S21 S11 S52 S12
A2
X1 X2
13 23
14 24
S33
Y2
S34
Y1
X3
37 47 57
38 48 58
X4
S22
Y39 Y40
Minotaur
MSR138DP
Gate
+24V DC
PowerFlex
AC Drive
Stop
Start
AC Line
Input Power
Common
Enable
*
M
1
2
3
4
Safe Off Option
IMPORTANT
The drive Enable digital input is a solid
state circuit. The safety outputs on safety
module must not be configured for
Pulsed/Safety Pulse Test.
