Honeywell BCU 465 - Bcu 460

BCU 460, BCU 465 · Edition 11.19 35
Air control
4.1.2 BCU..F3
VAS VAG
VR..L
V1 V2
UVS
BCU 460
LM..F3
60 61 65
22
µC
81
82
95
96
Process control (PCC)
FCU 500
2
4
A
1
Start 1
3 6
35
P
HT
PLC
The BCU with LM..F3 activates an air valve for purging,
cooling or starting the burner. The required air capacity
is released by the air valve.
As soon as there is a purge signal at terminal 3 of BCU..
F3, the air valve is activated by the output at terminal
65. The protective system (FCU500) starts the pre-
purge time if there is adequate air flow. After the elapse
of the pre-purge time, the air valve closes for ignition.
Once the protective system (terminal 35, safety inter-
locks) has issued the enable signal, the burner can be
started by the start-up signal at terminal1. The gas
valves for the 1
st
stage are opened and the burner is
ignited (on the BCU..C1 after a successful valve check).
After the operating signal has been received from the
burner, the gas valve for the 2
nd
stage opens.
Staged control
A048 = 0, 1 or 2
Depending on parameters A048 and A049, the con-
trol element may be activated either by the program
or externally via the input at terminal4, see also from
page93 (Air actuator control).