BCU 480 · Edition 06.07
55
BCU switched off
7 .10
In general, the BCU cannot be activated when no mains volt-
age 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.
If the unit is switched off, an immediate program abort with
switch-off of all outputs occurs (even during the safety time).
When the unit is switched on, the program run is restarted
in standby.
Furnace control
7 .11
Switch on the system to start up the furnace, then release the
burner start via the safety interlocks and afterwards start the
burner control so that the burner control unit may monitor the
burners as intended. To shut down the furnace, first disconnect
the burner control unit from the temperature control (burner
ON signal), then disconnect the safety interlocks and finally
switch off the system.
Mains switch
7 .12
The mains switch in the unit isolates the BCU on two poles
from the mains. It does not meet the requirements of EN
50156-1:2004 (5.2.2 Switch disconnectors) set out in chapter
5 for a device to disconnect the power supply.
Although the mains switch cannot be used for disconnecting
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 function is required for manual
operation and, in the case of PROFIBUS units, to switch off the
unit without causing BUS errors.
Disconnection for electrical maintenance work is to be im-
plemented with an external switch per unit or group only, in
accordance with Standard EN 50156.
Note on EC type-examination
7 .13
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 respective application.
Project planning information
