BCU 460, BCU 465 · Edition 11.19
87
Parameters
11 .7 Safety limits
Parameters A016 and A019 can be used to adjust the
safety limits (low air pressure protection and safety
time during operation) to the system requirements.
11 .7 .1 Delayed low air pressure protection
Parameter A016
This parameter defines whether the gas enable is sent
with or without an air pressure switch signal at termi-
nal 36. The parameter can be adjusted if low air pres-
sure protection is active (e.g. parameter I069 = 1 and
A101 = 1 to 7).
The minimum air pressure is ensured using the air
min.
air
pressure switch connected to terminal 36, for example,
while the air actuator for the combustion air is switched
on. Activation of the low air pressure protection device
and the shut-down properties can be set using param-
eter A016. If the air pressure falls below the value set on
the air
min.
air pressure switch, the signal to terminal 36
is interrupted and the BCU initiates a reaction depend-
ing on the parameter setting. When the air actuator is
switched off, the “no flow” state (default position) of the
air pressure switch (PDZ) is checked.
BCU
µC
P
62
60
61
38
p
e
/2
TC
PZ
36
PDZ
If air flow monitoring is active, the “no flow” state of
the air flow monitoring pressure switch (PDZ) is also
checked.
Parameter A016 = 0: Off. Air pressure monitoring takes
place immediately. The gas is only released when the
signal is received from the air pressure switch. Param-
eter A048 (Air actuator control) must be set to 1 for this
function (air with 1
st
gas stage).
Parameter A016 = 1: On. The air pressure is monitored
after a delay of up to the maximum running time set in
parameter A042 or until the position for maximum ca-
pacity is confirmed by the actuator.