PFU 780 · Edition 02.12
53
Project planning information
6 .12 Furnace control
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.
6 .13 Note on EC type-examination
Since EN 298 (1993) does not describe all functions of the PFU,
the operator is responsible for ensuring that all parameters
and functions are matched to the respective application.
6 .14 Mains switch
The mains switch in the unit isolates the PFU 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 implemented with an external switch per unit or
group only, in accordance with Standard “EN 50156”.
6 .15 Changing parameters
In certain cases, it may be necessary to change the default
settings. Using a separate software package and a PC opto-
adapter, it is possible to modify certain parameters on the
PFU, such as the switch-off threshold of the flame amplifier,
the behaviour in the event of a flame failure or if the pilot
burner is to burn permanently in the case of pilot and main
burner monitoring.
The software package with PC opto-adapter, as well as
“Changed parameters” stickers, are available as accesso-
ries – see section entitled page 55 (Accessories) .
The unit parameters set at the factory are specified in the
delivery note.
Document changed parameters in BCSoft using the protocol
function and enclose the protocol with the plant documentation.
If a replacement is ordered for a PFU with changed parameters,
refer to the protocol for details.