Rockwell Automation 20C-DG01 PowerFlex 700H AC Drive Safe Torque Off Option - Manual (Page 19)

Rockwell Automation Publication 20C-UM001B-EN-P - June 2011 19
Installation and Wiring Chapter 2
Application Considerations – When the hazard analysis for the overall machine
determines the need for external mechanical brakes or other stopping means, the
external means shall be activated after the removal of power for Stop Category 0.
When used, the E-stop button must utilize direct-opening contacts. The button
must latch to an open state when the contacts open. The button must be red with
a yellow background.
Fault Detection – A redundant (two) set of double break contacts on the Trojan
gate interlock are designed to ensure that at least one signal is sent to the Safe
Torque Off option board when the gate is opened. A single fault detected on the
safety input circuits will result in the lock-out of the system to a safe state (off ) at
the next operation and will not cause loss of the safety function.
Each of the inputs on the Safe Torque Off option board independently monitors
the status of the safety circuit and the status of the other input on the board.