PFU 780 · Edition 02.12l
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Project planning information
6 .5 Emergency stop
6 .5 .1 In the event of fire or electric shock
If there is a risk of fire, electric shock or similar, inputs
L1, N and 26e (safety interlocks) of the PFU should be
disconnected from the electrical power supply – this
should be reflected in the wiring on site.
6 .5 .2 Via the safety interlocks (limits)
The safety interlock turns off the power to input 26e,
such as in the event of air deficiency or similar.
6 .6 Reset
6 .6 .1 Parallel reset
Several burner control units can be reset in parallel us-
ing the external button. The PFU cannot be reset by
mains failure.
6 .6 .2 Permanent remote reset
Permanent remote reset gives rise to a malfunction. If a
remote reset signal is permanently applied to terminals
10c/12c,
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flashes on the display to indicate a fault.
Reset with a pulse < 1 s.
6 .6 .3 Automatic remote reset (PLC)
In the case of automatic remote reset (PLC), the reset
pulse duration should not exceed 1 second. Check
compliance with standards.
If a fault is acknowledged by remote reset too often, er-
ror
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(Too many remote resets) is displayed. The error
can only be acknowledged with the Reset/Information
button on the unit.
The burner malfunction must be remedied. The mal-
function can not be remedied by changing the method
of activation.
6 .6 .4 Burner start
A furnace start may only be initiated, if it has been en-
sured using an appropriate procedure that there is no
combustible mixture in the combustion/processing
chamber, in the connected areas or in the exhaust gas
system (heat exchanger, dust collector). This can be
achieved by pre-purge, which occurs immediately be-
fore ignition or within the period specified in the operat-
ing instructions.
In the case of multiple burner applications, pre-purge is
not necessary after a normal burner shut-down.
Note the requirements of the Standards. For exceptions,
see Standards.
6 .6 .5 Restart and start-up attempts
The precondition for a restart/start-up attempt is that
activation of the restart allows the burner to restart as
intended (in all operating phases). In this case, it must
be ensured that the program sequence started by the
PFU matches the application.
Note the requirements of the Standards. For exceptions,
see Standards.