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BCU 560, BCU 565 · Edition 02.16
60
Parameters > Flame control
11 .2 .3 High temperature operation
Parameter 06
Operation of firing systems above 750°C. The BCU..D1 and
BCU..D2 have a fail-safe input with the function “High tempera-
ture operation”. If firing systems are operated 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 op-
eration 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 56x..D
49
5
µC
BCU 56x..D
49
5
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
88
04
02
03
00
ϑ
t
t
FS1
1
46
11
9
5
13
V1
14
V2
49
HT
11
L1
42
41
If the temperature in the furnace chamber drops below 750°C,
the HT input must be disconnected from the electrical power
supply and the furnace must then be operated with flame control.
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