Pilz PSS SB HYD, Basic license - Manual (Page 38)

4-8
Intended Use
Modular Block System: Hydraulic Presses
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 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.