Pilz PSS SB NOT, Basic license - Manual (Page 27)

4-5 Modular Block System: Emergency Stop Circuits
• If wiring is to be laid outside the control cabinet, feedback loops must use
test pulses.
• Feedback loops must use test pulses if the possibility of a short-circuit
cannot be excluded.
• If only one contactor is used to switch a potentially dangerous drive, it
must be possible to switch this off via a group contactor within the
current path (selective shutdown).
• The group contactor must also be monitored through a feedback loop.
SB067: Feedback loop monitoring
SB067 is a standard function block for the direct control and monitoring of
contactors up to category 4, in accordance with EN 954-1, 03/97.
Features and application areas:
• Feedback loop is monitored during the change in the enable flag and
while the contactor is in a static condition.
• Feedback loop can be monitored on two separate feedback loops of
main contactors connected in series.
• Feedback loop can be monitored on group contactors.
INFORMATION
Input circuitry:
• To achieve category 4, two independent shutdown routes must be
provided within the current path of the potentially dangerous drive.
• If wiring is to be laid outside the control cabinet, feedback loops must use
test pulses.
• Feedback loops must use test pulses if the possibility of a short-circuit
cannot be excluded.
• If only one relay is used to switch a potentially dangerous drive, it must
be possible to switch this off via a group contactor located within the
current path (selective shutdown).
• The group contactor must also be monitored through a feedback loop.