BCU 370 · Edition 01.19
48
Parameters
4 .4 Behaviour during operation
4 .4 .1 Minimum operating time t
B
Parameter 10
Defines the minimum burner operating time.
To stabilize the burner operation, a minimum operating
time can be set independently of the central control
system.
If the start-up signal (
ϑ
) drops once the first safety time
t
SA1
has started to elapse, the burner remains in opera-
tion for at least time t
B
. The minimum operating time
t
B
starts to elapse following controller enable. If the
start-up signal drops before the first safety time t
SA1
,
e.g. during pre-purge, the control unit reverts directly to
standby and the burner is not ignited.
4 .4 .2 Controller enable signal delay time t
RF
Parameter 29
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
Defines the time between start-up of the burner and
controller enable.
The controller enable signal delay time ensures a stable
combustion process, e.g. through uniform heating of
the entire combustion chamber.
The time t
RF
starts to elapse
after expiry of
if
t
SA1
t
FS1
= 0, t
SA2
= 0
t
FS1
t
SA2
= 0
t
SA2
t
FS2
= 0
t
FS2
t
FS1
> 0, t
SA2
> 0, t
FS1
> 0
The BCU shows program status
H8
. After time t
RF
has elapsed,
the BCU closes the operation signalling contact (terminals
17/18) and activates controller enable (terminal 25).
4 .4 .3 Safety time during operation t
SB
Parameter 09
Defines the safety time during operation t
SB
for valves
V1, V2 and V3.
If there is a flame failure while the burner is operating, the
BCU closes the valves within the safety time during op-
eration t
SB
. The default in accordance with EN 298 is 1 s.
The safety time during operation t
SB
can also be set to 2 s.
Prolonging the time increases the installation availability
in the case of brief-duration fades of the flame signal.
The safety time of the installation during operation (in-
cluding closing time of the valves) may not exceed 3 s in
accordance with EN 746-2 or 4 s in accordance with NF-
PA 85 and NFPA 86. Please note application standards.