Bcu Switched Off; Note On Ec-Type Examination; Mains Switch; Sil/Pl Level For Thermoprocessing Equipment - Honeywell BCU 460 Technical Information

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6 .19 BCU switched off

In general, the BCU cannot be activated when no mains
voltage is applied or the burner control unit is switched
off.
The fault signalling contact is only closed when the unit
is supplied with voltage and switched on.

6 .20 Note on EC-type examination

Since EN 298 (1993) does not describe all functions of
the BCU, the operator is responsible for ensuring that
all parameters and functions are matched to the re-
spective application.

6 .21 Mains switch

The mains switch in the unit isolates the BCU on two
poles from the mains. It does not meet the require-
ments of EN 50156-1:2004 (5.2.2 Disconnecting
switch) set out in chapter 5 for a device to disconnect
the power supply.
Although the mains switch cannot be used for discon-
necting from the electrical power supply in accordance
with EN 50156, it does allow the burner to be isolated
functionally from the central control system. This func-
tion is required for manual operation and, in the case of
PROFIBUS units, to switch off the unit without causing
bus errors.
BCU 460, BCU 465 · Edition 03.16l
Disconnection for electrical maintenance work is to be
implemented with an external switch per unit or group
only, in accordance with Standard EN 50156.
6 .22 SIL/PL level for thermoprocessing
equipment
Since thermoprocessing installations include different
safety functions, it is not possible to determine a single
SIL/PL level for an entire installation, but this must be
determined separately for every safety function of the
installation.
See also page 86 (Safety-specific characteristic val-
ues).
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