Honeywell Krom Schroder PFU 780 Manual

6 Edition 02.12l
Industrial & Commercial Thermal
AGA
Technical Information · GB
Burner control unit PFU 780
• For pilot and main burners of unlimited capacity in
thermoprocessing equipment pursuant to EN 7462
• Separate flame control for pilot burner and main burner by UV,
ionisation or a further option of using the furnace chamber
temperature
• Display of the program status, unit parameters and flame signal;
Manual mode for burner adjustment and for diagnostic purposes

PFU 780 · Edition 02.12l 2
▼= To be continued
Table of contents
Burner control unit PFU 780.........................1
Table of contents ....................................2
1 Application ........................................4
1.1 Examples of application ...........................6
1.1.1 Stage-controlled main burner with alternating
pilot burner ..................................................6
1.1.2 Stage-controlled main burner with permanent
pilot burner ..................................................7
1.1.3 Modulating-controlled burner ........................8
1.1.4 PFU 780..D: High temperature equipment............9
2 Certification ..................................... 10
3 Function ..........................................11
3.1 Connection diagram ..............................11
3.1.1 PFU 780 ..............................................11
3.1.2 PFU 780..K2 .........................................12
3.2 PFU 780 program sequence......................13
3.3 Program status and fault messages..............16
4 Parameters .......................................18
4.1 Scanning the parameters.........................19
4.2 Flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.1 Flame signal, pilot burner ...........................20
4.2.2 Flame signal, main burner...........................20
4.2.3 Program status when the most recent fault
occurred . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.4 Switch-off threshold of the flame amplifier.........20
4.2.5 High temperature operation with PFU..D . . . . . . . . . . . .21
4.2.6 UVS check ...........................................24
4.3 Pilot and main burner monitoring ................25
4.3.1 Permanent pilot burner...............................27
4.3.2 Interrupted pilot burner .............................28
4.4 Behaviour in start-up position/standby ..........29
4.4.1 Flame simulation check in start-up position/
standby ....................................................29
4.4.2 Minimum burner pause time tBP ....................30
4.5 Behaviour during start-up ........................31
4.5.1 Safety time on start-up tSA ..........................31
4.5.2 Flame proving period tFS ........................... 32
4.5.3 Minimum combustion time tB...................... 32
4.5.4 Burner start-up attempts ...........................33
4.6 Behaviour during operation.......................35
4.6.1 Safety time during operation tSB for pilot and main
burners ....................................................35
4.6.2 Fault lock-out or restart, pilot burner ...............35
4.6.3 Fault lock-out or restart, main burner................37
4.7 Air valve control PFU..L ...........................39
4.7.1 Purge.................................................39
4.7.2 Cooling in start-up position/standby ...............39
4.7.3 Burner start ..........................................39
4.7.4 Air valve opens in the case of external activation
(not during start-up).......................................40
4.7.5 Air valve opens in the case of external activation
(even during start-up) ......................................41
4.7.6 Air valve opens with valve V2 ........................ 42
4.7.7 Air valve opens with operating signal ................43
4.7.8 Low fire over run time tKN after a normal shut-down44
4.7.9 Behaviour of the air valve in the event of a fault
lock-out....................................................45
4.8 Manual operation ................................ 46
4.8.1 Manual mode limited to 5 minutes..................46
4.9 Password .........................................47
5 Selection ........................................ 48
5.1 Calculating the safety time tSA .................. 48
5.2 Selection table ....................................49
5.2.1 Type code............................................49
6 Project planning information .................... 50
6.1 Cable selection .................................. 50
6.1.1 Ignition cable ........................................50
6.1.2 Ionisation cable .....................................50
6.1.3 UVLeitung ..........................................50
6.2 Ignition electrode ................................ 50
6.2.1 Electrode gap .......................................50

PFU 780 · Edition 02.12l 3
▼= To be continued
6.2.2 Star electrodes ......................................50
6.3 Minimum combustion time.......................51
6.4 Safety interlocks (Limits) .........................51
6.5 Emergency stop ..................................52
6.5.1 In the event of fire or electric shock . . . . . . . . . . . . . . . . . 52
6.5.2 Via the safety interlocks (limits)..................... 52
6.6 Reset ..............................................52
6.6.1 Parallel reset......................................... 52
6.6.2 Permanent remote reset ............................ 52
6.6.3 Automatic remote reset (PLC) ...................... 52
6.6.4 Burner start ......................................... 52
6.6.5 Restart and start-up attempts ...................... 52
6.7 Fault message ....................................53
6.8 Protecting the pilot burner from overload ........53
6.9 Installation........................................53
6.10 Wiring............................................53
6.10.1 UVS sensor wiring..................................53
6.11 PFU switched off ................................53
6.12 Furnace control .................................54
6.13 Note on EC type-examination...................54
6.14 Mains switch ....................................54
6.15 Changing parameters ...........................54
7 Flame control .....................................55
7.1 With ionisation sensor ............................55
7.2 With UV sensor ....................................55
7.3 Via the temperature in high temperature
equipment ............................................55
8 Accessories ...................................... 56
8.1 High-voltage cable ...............................56
8.2 BCSoft ............................................56
8.3 Stickers for labelling ..............................56
8.4 “Changed parameters” stickers ..................56
8.5 Radio interference suppressed electrode
adapters ..............................................57
8.6 Socket connectors ................................57
8.7 Module subrack ...................................57
8.8 Power supply PFP 700............................58
8.9 Relay module PFR 704 ...........................59
8.10 Field bus interface PFA 700.................... 60
8.11 Impulse system MPT 700 .......................61
9 Technical data ....................................62
9.1 Safety-specific characteristic values .............64
9.2 Operating controls................................65
10 Maintenance cycles ............................ 66
11 Legend ..........................................67
12 Glossary ........................................ 68
12.1 Waiting time tW..............................68
12.2 Safety time on start-up tSA ..................... 68
12.3 Ignition time tZ................................. 68
12.4 Flame simulation/Flame simulation delay
time tLV ..........................................68
12.5 Safety time during operation tSB .............69
12.6 Flame signal .....................................69
12.7 Fault lock-out ....................................69
12.8 Safety interlocks (Limits) ........................69
12.9 Pilot gas valve V1 ................................69
12.10 Main gas valve V2 ..............................69
12.11 Continuous operation ..........................70
12.12 Air valve.........................................70
12.13 Diagnostic coverage DC .......................70
12.14 Mode of operation..............................70
12.15 Safe failure fraction SFF .......................70
12.16 Probability of dangerous failure PFHD........70
12.17 Mean time to dangerous failure MTTFd.......70
Feedback ...........................................71
Contact.............................................71

PFU 780 · Edition 02.12l 4
Application
Module subrack
BGT for instance
serves to accom-
modate several
function units. It
is provided with
a backplane with
screw terminals
for simple, reliable
wiring.
1 Application
The burner control units PFU 780 control, ignite and
monitor gas burners for intermittent or continuous op-
eration. As a result of their fully electronic design they
react quickly to various process requirements and are
therefore also suitable for frequent cycling operation.
The PFU 780 can be used for industrial burners of un-
limited capacity which are ignited by pilot burners. Pilot
and main burners are controlled and monitored inde-
pendently. This reduces the main burner start-up time.
The pilot burner can burn permanently or be switched
off. The main burners may be modulating or stage-
controlled.
On industrial furnaces, the PFU 780 reduces the load
on the central furnace control by taking over tasks that
only relate to the burner, for example it ensures that
the burner always ignites in a safe condition after it has
been restarted.
The burner control unit is used for burners with me-
chanical combustion air supply where the fan is con-
trolled by a separate logic and for atmospheric burners.
The air valve control on the PFU 780L assists the fur-
nace control for cooling, purging and capacity control
tasks.
The program status, the unit parameters and the level
of the flame signal can be read directly from the unit.
Pilot and main burners can be controlled manually for
commissioning and diagnostic purposes.
▼

PFU 780 · Edition 02.12l 5
Application
If the local requirements on the burner control units
change, the PC software BCSoft can be adjusted to the
unit parameters of the application by using the optical
interface.
To support service personnel, BCSoft offers a conveni-
ent visualisation system of the input and output signals
and the error history.
Bogie hearth forging furnace in the metallurgical industry
Intermittent shuttle kiln in the ceramics industry
Walking beam furnace with overhead firing

PFU 780 · Edition 02.12l 6
VR..L
VAG
SPS
PLC
CPE
DI
L1, N, PE
P
2
1
t
1
2
ϑ1
ϑ2
A
P
DI
UV
02–0402–04 06–08 06–08
VBY
PFU 780 10e
2c
4c
18a
26e10c
22e
22a
28c16c18e
6a
6e
2e
4e
14a30e 10a
TZI
2
1
ϑ1 ϑ2
µC
Application
1.1 Examples of application
1.1.1 Stage-controlled main burner
with alternating pilot burner
Control: Main burner ON/OFF.
The main burner can be started with
reduced capacity after the operat-
ing signal from the pilot burner has
been detected. The pilot burner is
switched off automatically after the
main burner has started up. When
the main burner is switched off, the
pilot burner automatically switches
on again.
A UV sensor monitors the flame sig-
nal from pilot and main burners. UV
sensor UVD 1 is used for continu-
ous operation, UV sensor UVS for
intermittent operation.

PFU 780 · Edition 02.12l 7
VR..R
VAG
SPS
PLC
CPE
DI
L1, N, PE
P
2
1
A
P
DI
VBY
PFU 780 10e
2c
4c
18a
26e10c
22e
22a
28c16c18e
6a
6e
2e
4e
14a30e 10a
TZI
t
1
2
0402–04 06–08 06–08 04
2
1
ϑ1 ϑ2
µC
ϑ1
ϑ2
26a
Application
1.1.2 Stage-controlled main
burner with permanent pilot
burner
Control: Main burner ON/OFF.
The main burner can be started with
reduced capacity after the operat-
ing signal from the pilot burner has
been detected. Pilot and main burn-
ers can be operated simultaneously.
Both are ionisation-controlled inde-
pendently.

PFU 780 · Edition 02.12l 8
VAG
VBY
SPS
PLC
CPE
DI
L1, N, PE
2
1
P
DI
BV+IC
mA
PFU 780 10e 2e
4e
2c
4c
6a
6e
26a
26e10c
TZI
22a
28c
16c18e
14a
18a
M
2
1
ϑ1 ϑ2
µC
Application
1.1.3 Modulating-controlled burner
Control: Main burner continuous
The butterfly valve for air BV is
moved to ignition position in order
to start the main burner. The main
burner can be started at low-fire
rate after the operating signal from
the pilot burner has been detected.
The control system controls the
burner capacity via the butterfly
valve for air BV after the operating
state has been signalled. Pilot and
main burners can be operated si-
multaneously.

PFU 780 · Edition 02.12l 9
STW
L1
>750 °C
µC
PFU 780..D
18a
26a
DI
22a
µC
PFU 780..D
18a
26a
DI
22a
Application
1.1.4 PFU 780..D: High
temperature equipment
The flame is controlled indirectly on
the basis of the temperature. During
the start-up process, as long as the
wall temperature is below auto igni-
tion temperature the flame must be
controlled by conventional meth-
ods. When the working temperature
has exceeded 750°C, the safety
temperature monitor (STW) takes
over the indirect flame control.

PFU 780 · Edition 02.12l 10
Certification
2 Certification
Certified pursuant to SIL
For systems up to SIL 3 pursuant to EN 61508
Pursuant to EN ISO 138491:2006, Table 4, the PFU
can be used up to PL e.
EC type-tested and certified
pursuant to
– Gas Appliances Directive (2009/142/EC) in conjunc-
tion with EN 298:200401,
Meets the requirements of the
– Low Voltage Directive (2006/95/EC),
– EMC Directive (2004/108/EC).
PFU..T is FM approved
Factory Mutual Research Class: 1997.
Suitable for applications pursuant to NFPA 86.
www.approvalguide.com
AGA approved
AGA
Australian Gas Association, Approval No.: 5597
www.aga.asn.au/product_directory

PFU 780 · Edition 02.12l 11
N (L2)
22e
16c
N
26e
30a
32c
230 V
F1
18e
2a
4a
a
2e
4e
s
2c
4c
m
sk1
V2
V1
L1 (L1)
max. 1 A, 24 V
v2
v1
6a
6e
n
c1
24 V
0 V
c2
10c
12c
10a
12a
30e
22a
P
DI
A
2
1
1
N
2
28c
26a
ϑ1
ϑ214a
14e
10e
12e
24c
20c
18a
l
20c
18a
N
26a
26a
N
28c 28c
18a
Z
I
UVS 1
2
324c
L
N
M
V2
V1
C
µC
SK
A
S
PFU 780
Function
3 Function
3.1 Connection diagram
For cable selection and wiring, see page 50 (Project
planning information).
3.1.1 PFU 780
For the explanation of symbols, see page 67 (Legend).

PFU 780 · Edition 02.12l 12
N (L2)
22e
16c
N
26e
30a
32c
230 V
F1
18e
2a
4a
a
2e
4e
s
2c
4c
m
sk1
V2
V1
L1 (L1)
max. 1 A, 24 V
v2
v1
6a
6e
n
c1
24 V
0 V
c2
10c
12c
10a
12a
30e
22a
P
DI
A
2
1
1
N
2
28c
26a
ϑ1
ϑ214a
14e
10e
12e
24c
20c
18a
l
20c
18a
N
26a
26a
N
28c 28c
18a
Z
I
UVS 1
2
324c
L
N
M
V2
V1
C
µC
SK
A
S
PFU 780..K2
Function
3.1.2 PFU 780..K2
As a replacement unit for burner control unit PFU 798.
For the explanation of symbols, see page 67 (Legend).

PFU 780 · Edition 02.12l 13
Function
3.2 PFU780programsequence
Normal start-up
If an “old” fault is still being sig-
nalled after switching on, it will be
necessary to reset this first.
The safety interlocks (terminal 26e)
must be closed and the burner con-
trol unit must be switched on.
The PFU 780 conducts a self-test
when in the start-up position (the
burner is switched off). If it does
not determine a malfunction of the
internal electronic circuitry or of the
flame sensors, the burner can be
started. The pilot burner start-up is
activated via the signal input “Start-
up signal ϑ1” (terminal 10e). Once
the start-up signal ϑ1 has been
applied, the PFU 780 opens valve
V1 and ignites the burner. The igni-
tion time tZis constant. If a flame
is detected during the safety time
tSA1, the flame proving period tFS1
starts after the safety time tSA1 has
elapsed.
If the pilot burner has been started
successfully and its flame has
stabilised, the burner control unit
issues the Enable signal for main
burner operation. The operation sig-
nalling contact for the pilot burner
(terminals 2c/4c) closes.
01
02
03
04
08
00
00
08
05
06
07
Switch on PFU 780
Pilot burner start-up
with ϑ1 signal
Safety interlocks (Limits)
In the event of fault signal:
Reset
If parameter P15 = 1:
flame simulation check
Wait until
waiting time tW
has elapsed
If parameter P15 = 0:
Flame simulation check
If no flame detected:
next start-up attempt (P10)
or fault lock-out
Start-up position/standby
Safety time tSA1
running (P22),
ignition in process,
V1 opens and min.
combustion time tB
starts to elapse (P20)
In the event of flame failure:
restart or fault lock-out
Operating signal
Pilot burner closes
Flame proving period tFS1
running (P23)
In the event of flame failure:
restart or fault lock-out
Main burner start-up
with ϑ2 signal
Wait until
min. burner pause time tBP
has elapsed (P21)
If parameter P15 = 0:
Flame simulation check
If no flame detected:
next start-up attempt (P11)
or fault lock-out
Safety time tSA2 running (P24),
V2 opens and
min. combustion time tB
starts to elapse (P20)
Normal shut-down
via ϑsignal for
pilot and main burners
If min. combustion time t
B
has elapsed:
Operation signalling contact
opens,
V1 and V2 close,
min. burner pause time t
BP
starts to elapse (P21)
In the event of flame failure:
restart or fault lock-out
Operating signal
Main burner closes
Flame proving period
tFS2 running (P25)
In the event of flame failure:
restart or fault lock-out
PFU 780
If the air valve control is used,
the unit offers the following
additional functions:
In start-up position, the air
valve can be opened for cool-
ing
A
(display A0).
Using parameter 31, it can be
determined whether the air
valve can be activated exter-
nally during start-up (display
A1).
The air valve can be set to open
together with V1 (display A2 )
via parameter 30.
▼

PFU 780 · Edition 02.12l 14
Function
01
02
03
04
08
00
00
08
05
06
07
Switch on PFU 780
Pilot burner start-up
with ϑ1 signal
Safety interlocks (Limits)
In the event of fault signal:
Reset
If parameter P15 = 1:
flame simulation check
Wait until
waiting time tW
has elapsed
If parameter P15 = 0:
Flame simulation check
If no flame detected:
next start-up attempt (P10)
or fault lock-out
Start-up position/standby
Safety time tSA1
running (P22),
ignition in process,
V1 opens and min.
combustion time tB
starts to elapse (P20)
In the event of flame failure:
restart or fault lock-out
Operating signal
Pilot burner closes
Flame proving period tFS1
running (P23)
In the event of flame failure:
restart or fault lock-out
Main burner start-up
with ϑ2 signal
Wait until
min. burner pause time tBP
has elapsed (P21)
If parameter P15 = 0:
Flame simulation check
If no flame detected:
next start-up attempt (P11)
or fault lock-out
Safety time tSA2 running (P24),
V2 opens and
min. combustion time tB
starts to elapse (P20)
Normal shut-down
via ϑsignal for
pilot and main burners
If min. combustion time t
B
has elapsed:
Operation signalling contact
opens,
V1 and V2 close,
min. burner pause time t
BP
starts to elapse (P21)
In the event of flame failure:
restart or fault lock-out
Operating signal
Main burner closes
Flame proving period
tFS2 running (P25)
In the event of flame failure:
restart or fault lock-out
The PFU coordinates the correct
program run for the pilot and main
burners. The main burner can be
started via the signal input “Start-
up signal ϑ2” (terminals 14a/14c) if
required.
Once the start-up signal ϑ2 has
been applied (terminals 14a and
14e), the PFU 780 opens valve V2.
The main burner is ignited by the
pilot burner.
If a flame is detected during the
safety time tSA2, the flame proving
period tFS2 starts after the safety
time tSA2 has elapsed. If the main
burner has been started success-
fully and its flame has stabilised,
the operation signalling contact
(terminals 6a/6e) closes.
Start-up of the pilot burner
without flame signal
If no flame is detected during the
safety time tSA1, either a fault lock-
out occurs or up to three further
start-up attempts occur. (Param-
eter 10, “Pilot burner start-up at-
tempts”).
The air valve can be set to open
together with V1 (display A4 )
via parameter 30.
The air valve can be set to open
together with V1 (display A3 )
via parameter 30.
The air valve can be set to open
together with V1 (display A5 )
via parameter 30.
The air valve can be set to open
with V2 or to be activated ex-
ternally (display A6 )via param-
eter 30.
▼

PFU 780 · Edition 02.12l 15
Function
Behaviour of the pilot burner in
the event of flame failure during
operation
If the flame fails during operation,
either an immediate fault lock-out
occurs or a restart occurs. This pro-
cedure can be set via the optical in-
terface (parameter 12, “Pilot burner
restart”).
Behaviour of the main burner in
the event of flame failure during
start-up
If no flame is detected during the
safety time tSA2, either a fault lock-
out occurs or up to three further
start-up attempts occur. (Param-
eter 11, “Main burner start-up at-
tempts”).
Behaviour of the main burner in
the event of flame failure during
operation
If the flame fails during operation,
either an immediate fault lock-out
occurs or a restart occurs. This pro-
cedure can be set via the optical in-
terface (parameter 13, “Main burner
restart”).
01
02
03
04
08
00
00
08
05
06
07
Switch on PFU 780
Pilot burner start-up
with ϑ1 signal
Safety interlocks (Limits)
In the event of fault signal:
Reset
If parameter P15 = 1:
flame simulation check
Wait until
waiting time tW
has elapsed
If parameter P15 = 0:
Flame simulation check
If no flame detected:
next start-up attempt (P10)
or fault lock-out
Start-up position/standby
Safety time tSA1
running (P22),
ignition in process,
V1 opens and min.
combustion time tB
starts to elapse (P20)
In the event of flame failure:
restart or fault lock-out
Operating signal
Pilot burner closes
Flame proving period tFS1
running (P23)
In the event of flame failure:
restart or fault lock-out
Main burner start-up
with ϑ2 signal
Wait until
min. burner pause time tBP
has elapsed (P21)
If parameter P15 = 0:
Flame simulation check
If no flame detected:
next start-up attempt (P11)
or fault lock-out
Safety time tSA2 running (P24),
V2 opens and
min. combustion time tB
starts to elapse (P20)
Normal shut-down
via ϑsignal for
pilot and main burners
If min. combustion time t
B
has elapsed:
Operation signalling contact
opens,
V1 and V2 close,
min. burner pause time t
BP
starts to elapse (P21)
In the event of flame failure:
restart or fault lock-out
Operating signal
Main burner closes
Flame proving period
tFS2 running (P25)
In the event of flame failure:
restart or fault lock-out
The air valve can be set to open
with V2 or to be activated ex-
ternally (display A7 ) via param-
eter 30.
The air valve can be set to open
with the operating signal or to
be activated externally (display
A8 ) via parameter 30.

PFU 780 · Edition 02.12l 16
Function
Program status DISPLAY Fault message (blinking*)
Start-up position/standby 00
Cooling A0
Waiting time/Pause time 1 Flame simulation, pilot burner
Safety time on start-up, pilot burner 2 Start-up without flame signal, pilot burner
Flame proving period, pilot burner 3 Flame failure during flame proving period, pilot burner
Operation, pilot burner 4 Flame failure during operation, pilot burner
Waiting time, main burner 5 Flame simulation, main burner
Safety time on start-up, main burner 6 Start-up without flame signal, main burner
Flame proving period, main burner 7 Flame failure during flame proving period, main burner
Operation, main burner 8 Flame failure during operation, main burner
Purge P0
Air valve A
High temperature operation** . .
10 Faulty remote reset
32 Supply voltage too low
33 Faulty parameterisation
35 Short-circuit on a valve output
36 Short-circuit on ignition or valve output
51 Safety interlock failure
3.3 Program status and fault messages
During operation, the 7-segment display shows the pro-
gram status. In the event of a fault, the PFU halts the
program run, the display blinks and it then displays the
cause of the fault.
The burner control unit can be reset using the Reset
button or the remote reset.
▼

PFU 780 · Edition 02.12l 17
Function
Program status DISPLAY Fault message (blinking*)
52 Permanent reset
53 Time between two start-ups is too short
In Manual mode, two dots will blink on the display in program status 01–08.
** Optionally available.

PFU 780 · Edition 02.12l 18
Parameters
4 Parameters
Description Parameter Value range Factory default
setting Adjustable*
Flame signal, pilot burner 01 0–30 µA
Flame signal, main burner 02 0–30 µA
Program status when the most recent fault occurred 03 x0–x8
Switch-off threshold, pilot burner 04 1–20 µA 1 µA
Switch-off threshold, main burner 05 1–20 µA 1 µA
Start-up attempts, pilot burner 10 1–4 1
Start-up attempts, main burner 11 1–4 1
Restart, pilot burner 12 0; 1 0 
Restart, main burner 13 0; 1 0 
Safety time during operation for V1 and V2 tSB 14 1; 2 s 1 s 
Flame simulation check in start-up position/standby 15 0; 1 1 
Permanent pilot burner 16 0; 1 1 
Minimum combustion time tB20 25 s tSA 
Minimum burner pause time tBP 21 0–250 s 0 s 
Pilot burner safety time on start-up tSA1 22 3; 5; 10 s 
Pilot burner flame proving period tFS1 23 0–25 s 0 s 
Main burner safety time on start-up tSA224 3; 5 s 
Main burner flame proving period tFS2 25 0–25 s 0 s 
Air valve control 30 0; 2; 3 0 
Air valve can be activated externally on start-up 31 0; 1 0 
Air valve closed/can be activated in the event of malfunction 32 0; 1 1 
High temperature operation** 33 2; 3
▼

PFU 780 · Edition 02.12l 19
Parameters
Description Parameter Value range Factory default
setting Adjustable*
Manual mode limited to 5 minutes 34 0; 1 1 
UVS check (1 x in 24 hours) 35 0; 1 0 
Low fire over run time 36 0; 5; 15; 25 s 0 s 
Purge 42 0; 1 1 
Multi-flame control 45 0; 1 0 
Password 50 0000–9999 1234 
* Adjustable using BCSoft software and a PC opto-adapter
** Please quote in your order.
0 = Function inactive
1 = Function active
On parameterisation, ensure that the program se-
quence started matches the application. Select the
parameters so that the burner can restart as intended
in all operating phases.
4.1 Scanning the parameters
During operation, the 7-segment display shows the pro-
gram status.
The flame signal and all following parameters of the
PFU can be scanned one after the other by repeatedly
pressing the Reset/Information button (for 2 s).
In the event of a fault, the PFU halts the program run,
the display blinks and it then displays the cause of the
fault in coded form.

PFU 780 · Edition 02.12l 20
Parameters
4.2 Flame control
4.2.1 Flame signal, pilot burner
Parameter 01
Flame signal of the pilot burner, display in μA, measur-
ing range: 0–30 μA.
4.2.2 Flame signal, main burner
Parameter 02
Flame signal of the main burner, display in μA, measur-
ing range: 0–30 μA.
4.2.3
Programstatuswhenthemostrecentfaultoccurred
Parameter 03
Program status when the most recent fault occurred
This indicates the program status in which the last
burner fault occurred (e.g. the unit indicates that a
flame simulation has been detected with a blinking
01 ).
In parameter 03, it is now shown which program posi-
tion the unit was in when the fault was detected (wait-
ing time 01 or standby 00 ).
Result: A flame simulation was detected during the
waiting time or standby.
4.2.4 Switch-off threshold of the flame amplifier
Parameter 04, pilot burner switch-off threshold
Parameter 05, main burner switch-off threshold
The sensitivity at which the burner control unit still de-
tects a flame can be set between 1 and 20 μA.
Example: In the case of UV control with the UV sensor
UVS, the signal of the burner to be monitored is influ-
enced by other burners.
The set value can be incremented in parameter 04 so
that only the flame of the system’s “own” burner is de-
tected.
The measured flame signal of the system’s “own” burner
should be at least 3 μA (empirical value) higher than the
set switch-off threshold.