BCU 460, BCU 465 · Edition 11.19
11
Application
1 .1 .4 Modulating control with defined ignition
position
VAS
VAG
V1
V2
V3
UVS
VAS 1
BCU 460..F1
60 61 62
65 66
22
3
6
µC
81
82
95
96
35
2
Process control (PCC)
P
4
A
1
Start 1
HT
40 41
BVA
IC 40
4
12
16 DI 1
7
DI 2
M
µC
18
IN
mA
FCU 500
PLC
The central control system starts the pre-purge. Input
DI 2 is activated via the air valve output of the BCU and
the butterfly valve BVA is set to the pre-purge position.
In the event of a temperature demand, the burner con-
trol unit BCU activates input DI 1 via the output at ter-
minal 65 and moves the butterfly valve to the ignition
position (condition: the IC 40 must have reached the
ignition position on the instant of ignition). The burner
starts.
The burner application “Burner 1 with pilot gas” (pa-
rameter A078 = 1) is selected so that the burner can be
started with a limited start fuel flow rate.
During operation, the BCU activates DI 1 and DI 2 using
outputs 65 and 66. This enables the analogue input IN
on the actuator IC 40. Depending on the capacity de-
mand of the temperature controller, the butterfly valve
BVA moves steplessly between the low-fire rate and the
high-fire rate to the position specified by the analogue
input IN, see page 110 (Operating mode 27).
DI 1/V1
DI 2/Air valve
IC 40 position
Valve position
Off
Off
closed
Closed
On
Off
low
Ignition position/Low-
fire rate
On
On
analogue chart 1
In acc. with chart 1
Off
On
high
Pre-purge/High-fire rate