BCU 370 · Edition 01.19
47
Parameters
4 .3 .7 2
nd
safety time on start-up, main burner t
SA2
Parameter 14
88
ϑ
t
21
24
1
16
3
30
29
31
13
19-20
4
V1
6
V3
5
V2
17-18
11
DG
max.
9
32
DG
min.
7
DL
90°
➔
0
0
➔
90°
t
SA1
06
H0
05
00
t
FS1
t
E
01
t
GV
P1 A2
t
PV
t
Z1
03 04
t
VZ
H8
07
t
FS2
A1
08
t
RF
t
SA2
The safety time on start-up t
SA2
determines when the
main burner valves will be closed in the event of flame
signal failure.
V3 is opened as the safety time t
SA2
starts to elapse.
One second before the end of the safety time t
SA2
, V2
is closed (parameter 27 = 0, “Interrupted pilot burner”)
or remains open (parameter 27 = 1, “Permanent pilot
burner”). If no flame signal is pending after elapse of
the safety time t
SA2
, the BCU performs a safety shut-
down. Valves V1, V2 and V3 are closed. The BCU carries
out up to 3 further start-up attempts, depending on
how parameter 07 “Burner start-up attempts” has been
set.
The setting of safety time t
SA2
is to be determined on
the basis of the burner capacity, the type of control and
the relevant application standard, e.g. EN 746-2, EN
676, NFPA 85 or NFPA 86.
4 .3 .8 2
nd
flame proving period, main burner t
FS2
Parameter 15
88
ϑ
t
21
24
1
16
3
30
29
31
13
19-20
4
V1
6
V3
5
V2
17-18
11
DG
max.
9
32
DG
min.
7
DL
90°
➔
0
0
➔
90°
t
SA1
06
H0
05
00
t
FS1
t
E
01
t
GV
P1 A2
t
PV
t
Z1
03 04
t
VZ
H8
07
t
FS2
A1
08
t
RF
t
SA2
Determines the flame proving period of the main burner
in pilot/main burner combinations.
This time elapses before the BCU starts the next pro-
gram step so as to give the flame time to stabilize.
The flame proving period t
FS2
starts to elapse once
safety time t
SA2
has expired.