Pilz PSS SB FT, Basic license - Manual (Page 78)

6-34 Modular Block System: Burner Management
Standard Function Blocks
Timing diagrams
Burner start-up without automatic start after a controlled shutdown
Failure of safety sequence, flame monitor sequence and general faults
Failure of one of the followign criteria
• Safety sequence CHAI = 0,
• Flame monitor sequence FLAs = 0,
• Error sequence ERR = 0
The ENBL output is set with a start pulse,
provided all criteria are fulfilled ( ERR,
GUAR, CHAI, FLAs).
With each burner start-up, a pulse at the
STEP output is created, with which all
SB149 blocks and SB 157 are reset.
Failure of air pressure during
burner operation (
RUN =1 ):
ENBL is reset.
Only after a reset signal can the ENBL-output
be set again via a start pulse. No automatic
restart is enabled.
With a pulse at NEXT,
air pressure monitoring
is activated
If the monitor sequence is energised
(
GUAR = 0), the behaviour is identical
to that of air pressure monitoring.
SB152