BCU 580 · Edition 11.15
57
10 .2 .3 High temperature operation
Parameter 06
Operation of firing systems at temperatures above 750°C
The BCU..D1 and BCU..D2 have a fail-safe input with the func-
tion “High temperature operation”. If firing systems are oper-
ated above 750°C, the system is considered to be an item
of high temperature equipment (see EN 746-2). Here, flame
control must be in operation until the furnace wall temperature
has exceeded 750°C.
Below 750°C, the flame is monitored by conventional means
(UV sensor or ionization electrode). In High temperature mode
(> 750°C), the flame may be controlled via the temperature
using a safety temperature monitor (STM) in order to increase
the system’s availability. This means that no incorrect flame
signals, e.g. signals from a UV sensor which interprets reflected
UV radiation as extraneous signals, may lead to faults.
FCU 500..H1
M
HT
18
HT
HT
BCU 580..D
49
5
8
µC
BCU 580..D
49
5
8
µC
5-8
STW
When the HT input is activated (terminal 49), the burner control
unit reverts to High temperature mode, i.e.:
the BCU operates
without evaluation of the flame signal. The safety function
of the device-internal flame control system is deactivated.
In High temperature mode, the gas valves are opened and
the burners are started as usual without monitoring the pres-
ence of a flame.
The precondition for this operating mode is that an external
flame supervision device ensures the presence of the flame
in a fail-safe manner indirectly via the temperature. For this
purpose, we recommend a safety temperature monitor with
double thermocouple (DIN 3440). The flame must be moni-
tored again by conventional means (UV sensor or ionization
electrode) in the event of sensor discontinuity or short-circuit,
failure of the safety temperature monitor or power failure.
Only if the temperature at the furnace wall has exceeded
750°C may voltage be applied to the HT input (terminal 49)
so as to activate High temperature mode.
t
SA1
t
Z
04
06
02
03
00
t
t
FS1
t
SA2
07
08
t
FS2
5
13
V1
1
14
V2
2
ϑ
1
ϑ
2
8
4
88
1
46
11
9
41
42
L1
1
43
2
49
HT
Parameters > Flame control
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