Rockwell Automation 1000 Safety Lockout System - Manual (Page 22)

Publication 1000-UM001B-US-P - July 2000
4-2 SLS Sequence of Operation
D. If an operator moves the SLS switch from ON to OFF, the following
will happen:
1. The safety relay circuit between terminals S10 and S11, and S21 and
S2 will open up to de-energize the safety relay, causing the safety
contacts terminals #13 and #14 between wires #1 and #3 to open
up. In addition, safety relay auxiliary contacts between terminals #33
and #34 and #43 and #44 will open dropping out 1CR. This will
cause IC to open up.
Note: If one of the contacts on the SLS switch does not open, or if
there is a short in the cable to the SLS switch, only one of the safety
relay contacts K1 or K2 will drop out IC. But, the safety relay will
lock up and not allow a re-start. Now, since one of the safety relay
auxiliary contacts K1 or K2 will remain closed, 1CR will remain
energized, preventing the SAFE pilot light from illuminating. Also, if
the contacts IC and 1CR between terminals S41 and S42 on the
safety relay have not re-closed, the safety relay will not allow a restart.
2. After IC has dropped out, the VSR will check for voltages greater
than 10V on the load side of IC through its redundant and broken
wire sensing circuit. The VSR will also check to see that the N.C.
positively guided auxiliary contact between wire #7 and #8 on IC is
closed. If these two conditions are met, the VSR will close the safety
contacts between its terminals #13 and #14.
3. Since the auxiliary contact of IC between ++ and wire #10 is closed,
the 1CR contact between wires #10 and #11 is closed, the safety
contacts between wire #11 and #12 are closed, and the SLS switch
contact between wire #12 and the SAFE pilot light is closed, the
SAFE pilot light will illuminate. The TB led between wire #12 and –
is on.
E. The SAFE pilot light will not come on with the SLS switch in the off
position if:
1. The VSR detects a voltage greater than 10V on the load side IC.
2. The VSR detects that the positively guided N.C. auxiliary IC contact
between wires #7 and #8 has not re-closed.
3. A safety relay auxiliary contact does not allow 1CR to drop out and
close circuit between wires #10 and #11.
4. The IC auxiliary contact between wires PLUS and #10 does not
re-close.