FCU 500, FCU 505 · Edition 02.17 11
Application
1.1.3 Safety limits (LDS) for
modulating burner control
The centrally checked safety func-
tions such as pre-purge, setting the
valve to ignition position via a but-
terfly valve control system, tight-
ness test, flow detector and pres-
sure switch check (gas
min.
, gas
max.
,
air
min.
) are provided by the FCU 500.
The capacity can be adjusted con-
tinuously by activating the control
element (analogue or 3-point step
signal).
To ensure that the correct air vol-
ume is available for ignition (start
fuel flow rate) when starting the
burners, the FCU sends the burner
start enable signal to the BCUs via
the “LDS (limits during start-up)”
output.
The circuit design of the safety
interlock and LDS outputs on the
FCU and the corresponding in-
puts on the BCUs ensures that the
burners can only start if the safety
interlocks and the LDS output have
enabled burner start-up.
FCU 500..F1
µC
P
DG DG DG
VAS
VAS
VCG
VCG
DG
min
DG
max
49 15 131450
53
45
47 4858
p
u
/2
M
PZL PZH PZ
PZL PDZ
TE
BCU 560..F0
M
M
TC
90°➔0°
0°➔90°
54
55
VAS
DGDG
>750°
ϑ
1
2
3
DL
min
DL
Purge
66
BCU 560..F0
66
16
57
STM
To Next Page
