Low Fire Over-Run Time T; Down - Honeywell Krom Schroeder BCU 480 Manual

Parameters

4 .7 .8 Low fire over-run time t

shut-down
A8
L1
A
P
VG..N
Parameter 36
Settings: 0; 5; 15 or 25 (low fire over-run time in sec-
onds)
BCU 480 · Edition 03.16l
after a controlled
KN
00 88
1
5
4 1
7
V1
12
1
9
16-17
1
21
2
14 V2
24 2
28-29
2
23
A
26
18-19
t
t
KN
BCU 480..L
1
SPS
2
PLC
CPE
VAS 1
GIK..B
1
2
VR..R
This parameter is applicable to systems with a pneu-
matic
air/gas ratio control system and On/Off control.
Parameter 36 = 0 (low fire over-run time t
Without low fire over-run, the gas circuit is closed im-
mediately owing to the quick-closing gas valve in the
case of On/Off control. The air circuit closes more slow-
ly. The air flowing in during the closing time increases
the O content in the combustion chamber.
2
Parameter 36 = 5; 15 or 25 (low fire over-run time
t = 5, 15 or 25 s):
KN
The air valve closes slowly after the activation signal has
been switched off. The gas valve remains open for t
This means that the burner, after deactivation of the
start-up signal (ϑ), is initially adjusted down to low fire
and then switched off completely.
Using the low fire over-run function reduces the O
content in the furnace atmosphere.
Flame control is still operational. Can be used only in
the case of a pneumatic air/gas ratio control system
and On/Off control. It must be ensured that no excess
gas occurs.
The low fire over-run time has an effect on the behav-
iour of the main burner only.
Background: the pilot burner is only used in single-
stage operation.
= 0 s):
KN
.
KN
2
53