Honeywell Krom Schroeder BCU 480 - High Temperature Operation in the Case of BCU; D2 or BCU

BCU 480 · Edition 03.16l 32
Parameters
4.2.5 High temperature operation in the case of
BCU..D2 or BCU..D3
Parameter 33
Operation of firing systems at temperatures above
750°C. The BCU features a safety-relevant DI input
(Digital Input). This input supports the “High tempera-
ture operation” function. If firing systems are operated
above 750°C, the system is considered to be an item
of high temperature equipment (see EN 7462). Flame
control must be in operation until the furnace wall tem-
perature has exceeded 750°C. Note the requirements
of the Standards!
Frequently, flame control is dispensed with so as to
achieve a particularly high flexibility of the installation.
This means that no incorrect flame signals, e.g. signals
from a UV sensor which are interpreted as extraneous
signals due to reflection of UV radiation, may lead to
faults.
When the DI input is activated, the burner control unit
reverts to high temperature operation. This means: the
BCU operates without evaluation of the flame signal.
The safety function of the device-internal flame con-
trol system is placed out of operation.
In High temperature mode, the gas valves are opened
without flame control.
The precondition for high temperature operation is that
an external flame safeguard ensures the presence of
the flame in fail-safe manner indirectly via the tempera-
ture. For this purpose, we recommend a safety temper-
ature monitor with double thermocouple (DIN 3440).
Sensor discontinuity, sensor short-circuit, failure of a
component or mains failure must set the installation to
a safe state.
The voltage may be applied to the DI input (terminal
6) so as to activate high temperature operation only
when the temperature at the furnace wall has exceeded
750°C. The BCU starts the burner as usual, without
monitoring the presence of the flame.
t
SA
t
Z
88 04 02 03 00
t
t
FS
4
5
1
7
9
18-19
12
V1
14 V2
16-17
6
DI
1
ϑ1
If the temperature in the furnace chamber drops below
750°C, the DI input must be disconnected from the
electrical power supply and the furnace must be oper-
ated with the internal flame control system.
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