PFU 760 Burner Control

PFU 760 Burner Control
Burner control unit PFU 760
Technical Information · GB
6.2.1.4 Edition 05.11
• For directly ignited burners of unlimited capacity in intermittent operation
or in continuous operation pursuant to EN 746-2
• Plug-in function unit for mounting in 19" module subracks
• Flame control by UV, ionization 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
• Visualization and adaptation to the specific application via the PC
programming and diagnostic software BCSoft to simplify logistics
management
• Air valve control relieves the furnace control
• Connection to PROFIBUS-DP via field bus interface PFA
• Certified for systems up to SIL 3 and compliant with PL e
www.kromschroeder.com
2
Contents
Burner control unit PFU 760 . . . . . . . . . . . . . . . . . . . . . . . . . 1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Examples of application . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.1 Staged On/Off burner control . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.2 Staged High/Low burner control . . . . . . . . . . . . . . . . . . . . . . 7
1.1.3 Two-stage-controlled burner . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.1.4 Modulating-controlled burner . . . . . . . . . . . . . . . . . . . . . . . . 9
1.1.6 PFU for PROFIBUS-DP with PFA 700 . . . . . . . . . . . . . . . . . . . 10
1.1.5 PFU 760..D: High temperature equipment . . . . . . . . . . . . . 10
2 Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 Connection diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1.1 PFU 760 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1.2 PFU 760..K1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1.3 PFU 760..K2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 PFU 760 program sequence . . . . . . . . . . . . . . . . . . . . . 15
3.3 Program status and fault messages . . . . . . . . . . . . . . 17
4 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 Scanning the parameters . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.1 Burner flame signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2 Program status when the most recent fault occurred . . . 20
4.2.3 Switch-off threshold of the flame amplifier . . . . . . . . . . . . 20
4.2.4 High temperature operation with PFU..D . . . . . . . . . . . . . 21
4.2.5 UVS check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.3 Behaviour in start-up position/standby . . . . . . . . . . . 25
4.3.1 Flame simulation check in start-up position/standby . . . . 25
4.3.2 Minimum burner pause time tBP . . . . . . . . . . . . . . . . . . . 26
4.4 Behaviour during start-up . . . . . . . . . . . . . . . . . . . . . . . 27
4.4.1 Safety time on start-up tSA . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.4.2 Flame proving period tFS . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.4.3 Minimum combustion time tB . . . . . . . . . . . . . . . . . . . . . . 27
4.4.4 Burner start-up attempts . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.5 Behaviour during operation . . . . . . . . . . . . . . . . . . . . 29
PFU 760 · Edition 05.11
4.5.1 Safety time during operation tSB for V1 and V2 . . . . . . . . . 29
4.5.2 Fault lock-out or restart . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.6 Switchable gas valve V2 on PFU..L . . . . . . . . . . . . . . . . 31
4.7 Air valve control PFU..L . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.7.1 Purge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.7.2 Cooling in start-up position/standby . . . . . . . . . . . . . . . . . 32
4.7.3 Burner start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.7.4 Air valve opens in the case of external activation (not
during start-up) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.7.5 Air valve opens in the case of external activation (even
during start-up) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.7.6 Air valve opens with valve V1 . . . . . . . . . . . . . . . . . . . . . . . 35
4.7.7 Air valve opens with valve V2 . . . . . . . . . . . . . . . . . . . . . . . 36
4.7.8 Low fire over run time tKN after a controlled shut-down . .37
4.7.9 Behaviour of the air valve in the event of a fault lock-out 38
4.8 Manual operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.8.1 Manual mode limited to 5 minutes . . . . . . . . . . . . . . . . . . 39
4.9 Password . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.10 Multi-flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5 Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.1 Safety time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.1.1 Calculating the safety time tSA . . . . . . . . . . . . . . . . . . . . . . 41
5.2 Selection table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.3 Type code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
6 Project planning information . . . . . . . . . . . . . . . . . . . . . 43
6.1 Cable selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.1.1 Ignition cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.1.2 Ionization cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.1.3 UV cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.2 Ignition electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.2.1 Electrode gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.2.2 Star electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.3 Minimum combustion time . . . . . . . . . . . . . . . . . . . . . 44
6.4 Safety interlocks (Limits) . . . . . . . . . . . . . . . . . . . . . . . . 44
6.5 Emergency stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
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= To be continued
3
6.5.1 In the event of fire or electric shock . . . . . . . . . . . . . . . . . . 44
6.5.2 Via the safety interlocks (limits) . . . . . . . . . . . . . . . . . . . . . 44
6.6 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
6.6.1 Parallel reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6.2 Permanent remote reset . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6.3 Automatic remote reset (PLC) . . . . . . . . . . . . . . . . . . . . . . .
6.6.4 Burner start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6.5 Restart and start-up attempts . . . . . . . . . . . . . . . . . . . . . .
45
45
45
45
45
6.7 Fault signalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.8 Protecting the burner from overload . . . . . . . . . . . . . 46
6.9 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.10 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.10.1 UVS sensor wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.11 PFU switched off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.12 Furnace control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.13 Note on EC type-examination . . . . . . . . . . . . . . . . . . . 47
6.14 Mains switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.15 Changing parameters . . . . . . . . . . . . . . . . . . . . . . . . . 47
7 Flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.1 With ionization sensor . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.2 With UV sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.3 Via the temperature in high temperature equipment 48
8 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.1 High-voltage cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.2 BCSoft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.3 Stickers for labelling . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.4 “Changed parameters” stickers . . . . . . . . . . . . . . . . . 49
8.5 Radio interference suppressed electrode adapters . 50
8.6 Socket connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
8.7 Module subracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
8.8 Power supply PFP 700 . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.9 Relay module PFR 704 . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.10 Flame detector PFF 704 . . . . . . . . . . . . . . . . . . . . . . . 53
8.11 Field bus interface PFA 700 . . . . . . . . . . . . . . . . . . . . . 54
PFU 760 · Edition 05.11
8.12 Impulse system MPT 700 . . . . . . . . . . . . . . . . . . . . . . 55
9 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
9.1 Safety-specific characteristic values . . . . . . . . . . . . . . 58
9.2 Operating controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
10 Maintenance cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
11 Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
12 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
12.1 Waiting time tW . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
12.2 Safety time on start-up tSA . . . . . . . . . . . . . . . . . . . . . 62
12.3 Ignition time tZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
12.4 Flame simulation/Flame simulation delay time tLV . 62
12.5 Safety time during operation tSB . . . . . . . . . . . . . . . 62
12.6 Flame signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
12.7 Fault lock-out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
12.8 Safety interlocks (Limits) . . . . . . . . . . . . . . . . . . . . . . . 63
12.9 Pilot gas valve V1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
12.10 Main gas valve V2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
12.11 Continuous operation . . . . . . . . . . . . . . . . . . . . . . . . 63
12.12 Air valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
12.13 Diagnostic coverage DC . . . . . . . . . . . . . . . . . . . . . . 64
12.14 Mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . 64
12.15 Safe failure fraction SFF . . . . . . . . . . . . . . . . . . . . . . . 64
12.16 Probability of dangerous failure PFHD . . . . . . . . . . 64
12.17 Mean time to dangerous failure MTTFd . . . . . . . . . 64
Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
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= To be continued
4
Module subrack
BGT for instance
serves to accommodate several
function units. It
is provided with
a backplane with
screw terminals
for simple, reliable
wiring.
1 Application
The burner control units PFU 760 control, ignite and monitor gas burners for intermittent or continuous operation. 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 760 can be used for directly ignited industrial burners.
The burners may be modulating or stage-controlled.
On industrial furnaces, the PFU 760 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 mechanical
combustion air supply where the fan is controlled by a separate
logic and for atmospheric burners.
PFU 760 · Edition 05.11
The air valve control on the burner control unit PFU 760L ­assists
the furnace control for cooling, purging and output control
tasks.
The program status, the unit parameters and the level of the
flame signal can be read directly from the unit. The burner
can be controlled manually for commissioning and diagnostic
purposes.
If the local requirements on the burner control unit change, the
PC software BCSoft can be adjusted to the unit parameters of
the application by using the optical interface.
The service personnel is supported by a convenient visualization system of the input and output signals and the error history.
To reduce the installation and wiring costs, Elster Kromschröder
offers the field bus interface PFA 700 to transfer the control
signals and feedbacks via PROFIBUS-DP.
Application
Bogie hearth forging furnace
in the metallurgical industry
PFU 760 · Edition 05.11
5
Intermittent shuttle kiln
in the ceramics industry
Walking beam furnace
with overhead firing
Application
6
1.1 Examples of application
1.1.1 Staged On/Off burner control
The burner can be started with reduced
capacity.
A UV sensor monitors the flame signal
from the burner. UV sensor UVD 1 is used
for continuous operation, UV sensor UVS
for intermittent operation.
L1, N, PE
P
DI
SPS
PLC
API
PFU 760L
22a 10c 26e
ϑ1
A
P
DI
30e
10a
10e
2e
4e
µC
2c
4c
22e 16c
28c
26a
TZI
UV
VAG
VR..R
PFU 760 · Edition 05.11
Application > Examples of application
7
1.1.2 Staged High/Low burner control
The burner starts at low-fire rate. When
the operating state is reached, the
PFU 760L advises the control unit. The
PLC can now pulse the air valve in order
to control the burner output.
L1, N, PE
P
DI
SPS
PLC
API
PFU 760L
22a 10c 26e
ϑ1
A
P
DI
30e
10a
10e
2e
4e
µC
2c
4c
22e 16c
28c
26a
TZI
GIK..B
VAS..N
VR..R
PFU 760 · Edition 05.11
Application > Examples of application
8
1.1.3 Two-stage-controlled burner
Control: ON/OFF with ignition via ­bypass
The burner starts at low-fire rate. When
the operating state is reached, the
PFU 760L issues the Enable signal for
the maximum burner output.
L1, N, PE
P
DI
SPS
PLC
API
PFU 760L
22a 10c 26e
ϑ1
A
P
DI
30e
10a
10e
µC
22e
18e 16c
28c
VBY
VAG
4
7
M
BVA + IC 40
PFU 760 · Edition 05.11
2c
4c
26a
TZI
2e
4e
Application > Examples of application
9
1.1.4 Modulating-controlled burner
Control: continuous
The external control system moves the
butterfly valve for air BVA to ignition
­position. The burner starts at low-fire
rate, and a controller in the PLC controls
the burner output via the butterfly valve
for air BVA after the operating state has
been signalled.
L1, N, PE
P
DI
SPS
PLC
API
mA
ϑ1
DI
PFU 760
22a 10c 26e
10e
2e
4e
µC
2c
4c
16c
28c
TZI
VAG
M
BVA+IC 20
PFU 760 · Edition 05.11
26a
BIO
BIC
Application > Examples of application
10
1.1.6 PFU for PROFIBUS-DP with PFA 700
The bus system transfers the control signals for starting, resetting and for controlling the air valve from the ­control system (PLC) to the PFU 760 via the PFA 700.
In the opposite direction it sends information on the operating status. Control
­signals that are relevant for safety, such
as the safety interlocks and digital input,
are transferred independently of the bus
communication by separate cables.
PROFIBUS-DP
L1, N, PE
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
BUS
PFA/PFP
SPS
PLC
API
P
BUS
DI
…
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFU 760
PFA/PFP
BUS
…
STW >750 °C
PFU 760..D
µC
L1
PFU 760..D
µC
18a
18a
22a
22a
DI
DI
PFU 760 · Edition 05.11
1.1.5 PFU 760..D: High temperature
equipment
Indirect flame control using the temperature. During the start-up process, as long
as the wall temperature is below auto
ignition temperature the flame must be
controlled by conventional methods.
When the working temperature has
­exceeded 750°C, the safety temperature monitor (STW) takes over the indirect
flame control.
11
2 Certification
AGA approved
Certified pursuant to SIL
AGA
Australian Gas Association, Approval No.: 5597
www.aga.asn.au/product_directory
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 conjunction
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.fmglobal.com  Products and Services  Product Certification  Approval Guide
PFU 760 · Edition 05.11
12
(
P
L1 (L1)
PFU 760
30e
sk1
16c
18e
26e
30a
32c
24c
2e
s 4e
28c
N
I
2c
m 4c
26a
PFF 704
24 V
8a
8c
0V
8e
A
8a
8c
8e
ϑ1
µC
S
SK
10e
12e
0V
A
10a
12a
10c
12c
1
UVS 2
3
N
28c
26a
PFU 760 · Edition 05.11
N
28c
26a
20c
24c
max. 1 A, 24 V
2a
a 4a
20c
230 V
24 V
V1
V2
22a
N (L2)
Z
N
22e
F1
DI
3 Function
PFU 760L)
3.1 Connection diagram
For cable selection and wiring, see page 43 (Project planning
information).
3.1.1 PFU 760
For the explanation of symbols, see page 61 (Legend).
Function > Connection diagram
(
P
L1 (L1)
30e
13
PFU 760L..K1)
PFU 760..K1
F2
F1
sk1
16c
18e
26e
DI
30a
32c
24c
2e
s 4e
28c
N
I
2c
m 4c
26a
PFF 704
8e
0V
24 V
A
8a
8c
8e
8a
8c
ϑ1
µC
S
SK
10e
12e
0V
A
10a
12a
10c
12c
1
UVS 2
3
N
28c
26a
PFU 760 · Edition 05.11
N
28c
26a
20c
24c
max. 1 A, 24 V
2a
a 4a
20c
230 V
24 V
V1
V2
22a
N (L2)
Z
N
22e
3.1.2 PFU 760..K1
As a replacement unit for burner control unit PFS/PFD 778.
For the explanation of symbols, see page 61 (Legend).
Function > Connection diagram
(
P
L1 (L1)
14
PFU 760L..K2)
PFU 760..K2
30e
F1
sk1
16c
18e
26e
DI
30a
32c
24c
2e
s 4e
28c
N
I
2c
m 4c
26a
PFF 704
8e
0V
24 V
A
8a
8c
8e
8a
8c
ϑ1
µC
S
SK
10e
12e
0V
A
10a
12a
10c
12c
1
UVS 2
3
N
28c
26a
PFU 760 · Edition 05.11
N
28c
26a
20c
24c
max. 1 A, 24 V
2a
a 4a
20c
230 V
24 V
V1
V2
22a
N (L2)
Z
N
22e
3.1.3 PFU 760..K2
As a replacement unit for burner control unit PFU 778.
For the explanation of symbols, see page 61 (Legend).
Function
15
Switch on PFU 760
PFU 760L
with air valve control features the
following additional functions.
In the event of fault signal:
Reset
Safety interlocks (Limits)
00
Start-up position/standby
In start-up position, the air valve
can be opened for ­cooling A .
If parameter P15 = 1:
Flame simulation check
01
Start-up with ϑ signal
Wait until
min. burner pause time tBP
has elapsed (P21)
Using parameter 31, it can be
determined whether the air
valve can be activated externally
­during start-up.
If parameter P15 = 0:
Flame simulation check
02
Safety time tSA
running (P22),
ignition in process,
V1 opens and
min. combustion time tB
starts to elapse (P20)
If no flame detected:
next start-up attempt (P10)
or fault lock-out
PFU 760 · Edition 05.11
03
Flame proving period t
The air valve can be set to open
together with V1 (display A2 ) via
parameter 30.
3.2 PFU 760 program sequence
Normal start-up
If an “old” fault is still being signalled
after switching on, it will be necessary
to reset this first.
When the safety interlocks are closed,
the PFU reverts to start-up position and
conducts a self-test. If it does not determine a malfunction of the internal electronic circuitry or of the flame sensor, the
burner can be started.
The flame simulation check is conducted
during start-up position or after applying
the start-up signal (ϑ), depending on
parameter 15.
After the min. burner pause time tBP has
elapsed, the PFU opens valve V1 and
ignites the burner. The ignition time tZ
is constant.
If a flame is detected during the safety
time tSA, the flame proving period tFS
starts after this safety time has elapsed.
Valve V2 opens and the operation
­signalling contact between terminals
2c and 4c closes. This completes startup. An adjustable min. combustion time
tB ensures that the burner burns for a
defined period even if the start-up signal
(ϑ) is switched off beforehand.
t
next start-up attempt (P10)
or fault lock-out
Function > PFU 760 program sequence
03
16
The burner can also be started manually
with the aid of the button on the PFU.
Voltage must be applied continuously
to terminals 10e, 26e and 30a in order
for this to occur.
The PFU can also be operated in Manual
mode for start-up.
Flame proving period tFS
running (P23)
In the event of flame failure:
fault lock-out
04
Operation signalling
contact closes
and V2 opens
In the event of flame failure:
restart or
fault lock-out
04
00
Controlled shut-down
via ϑ signal
If min. combustion time tB
has elapsed:
Operation signalling
contact opens,
V1 and V2 close,
min. burner pause time tBP
starts to elapse (P21)
PFU 760 · Edition 05.11
The air valve can also be set to
open with V2 or to be ­activated
externally (display A4 ) via
­parameter 30.
Start-up without flame signal
If no flame is detected during the safety
time tSA, either a fault lock-out occurs
or up to three further start-up attempts
occur. The required functions and, if
­applicable, the number of start-up
­attempts must be specified when ordering. (Parameter 10, “Burner start-up
attempts”).
Behaviour 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 procedure can be
set via the optical interface (parameter
12, “Burner restart”).
Function
17
3.3 Program status and fault messages
During operation, the 7-segment display shows the program
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.
Program status
Start-up position/standby
DISPLAY
00
Fault message (blinking*)
Cooling
A0
Waiting time/Pause time
1
Flame simulation, pilot burner
Burner safety time on start-up
2
Burner start-up without flame signal
Burner flame proving period
3
Flame failure during burner flame proving period
Burner operation
4
Flame failure during operation, pilot burner
Purge
P0
Air valve
A High temperature operation**
. .
10
Faulty remote reset
32
Supply voltage too low
33
Faulty parameterization
35
Short-circuit on a valve output
36
Short-circuit on ignition or valve output
51
Safety interlock failure
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 – 04.
** Optionally available.
PFU 760 · Edition 05.11
18
4 Parameters
Description
Burner flame signal
Program status when the most recent fault occurred
Burner switch-off threshold
Burner start-up attempts
Burner restart
Safety time during operation for V1 and V2 tSB
Flame simulation check in start-up position/standby
Minimum combustion time tB
Minimum burner pause time tBP
Burner safety time on start-up tSA
Burner flame proving period tFS
Switchable gas valve V2 (only on PFU..L)
Air valve control
Air valve can be activated externally on start-up
Air valve closed/can be activated in the event of malfunction
High temperature operation **
t
PFU 760 · Edition 05.11
Parameter
Value range
01
03
04
10
12
14
15
20
21
22
23
26
30
31
32
33
0 – 30 μA
x0 – x8
1 – 20 µA
1 – 4
0; 1
1; 2 s
0; 1
25 s
0 – 250 s
3; 5; 10 s
0 – 25 s
0; 1
0; 1; 2
0; 1
0; 1
2; 3
Factory default
setting
1 µA
1
0
1s
1
tSA
0s
Adjustable*








0s
0
0
0
1





Parameters
Description
19
Parameter
Value range
Manual mode limited to 5 minutes
UVS check (1 x in 24 hours)
34
35
Low fire over run time
36
Purge
Multi-flame control
Password
42
45
50
0; 1
0; 1
0; 3; 5; 10; 15;
25; 60 s
0; 1
0; 1
0000 – 9999
* Adjustable using BCSoft software and a PC opto-adapter.
** Please quote in your order.
0 = Function inactive,
1 = Function active.
On parameterization, ensure that the program sequence
matches the application. Select the parameters so that the
burner can be operated as intended in all operating ­phases.
4.1 Scanning the parameters
During operation, the 7-segment display shows the program
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 760 · Edition 05.11
Factory default
setting
1
0
Adjustable*


0s

1
0
1234



Parameters
4.2 Flame control
4.2.1 Burner flame signal
Parameter 01
Flame signal of the burner, display in µA, measuring range:
0 – 30 µA.
4.2.2 Program status when the most recent fault occurred
Parameter 03
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 position the
unit was in when the fault was detected (waiting time 01 or
standby 00 ).
Result: A flame simulation was detected during the waiting
time or standby.
PFU 760 · Edition 05.11
20
4.2.3 Switch-off threshold of the flame amplifier
Parameter 04, burner switch-off threshold
The sensitivity at which the burner control unit still detects 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 influenced by other
burners.
The set value can be incremented in parameter 04 so that only
the flame of the system’s “own” burner is detected.
The measured flame signal of the system’s “own” burner should
be at least 3 µA (empirical value) higher than the set switchoff threshold.
Parameters > Flame control
4.2.4 High temperature operation with PFU..D
Parameter 33
Operation of firing systems at temperatures above 750°C. The
PFU features a safety-relevant DI input (Digital Input). This input
supports the “High temperature operation” function. If firing
systems are operated above 750°C, the system is considered
to be a high temperature equipment (see EN 746-2). Flame
control must be in operation until the furnace wall temperature
has exceeded 750°C. Note the requirements of the Standards!
Flame control can be dispensed with during high temperature
operation to improve the system availability. This means that
no incorrect flame signals, e.g. signals from a UV sensor which
are interpreted as extraneous signals due to reflection of UV
radiation, may lead to faults.
When the DI input is activated, the burner control unit reverts
to High temperature mode. This means: the PFU operates
without evaluation of the flame signal. The safety function of the
device-internal flame control system is placed out of operation.
In High temperature mode, the gas valves are opened without
flame control.
The precondition for high temperature operation is that an
external flame safeguard ensures the presence of the flame
in fail-safe manner indirectly via the temperature. For this
purpose, we recommend a safety temperature monitor with
twin thermocouple (DIN 3440). Sensor discontinuity, sensor
short-circuit, failure of a component or mains failure must set
the installation to a safe state.
PFU 760 · Edition 05.11
21
The voltage may be applied to the DI input (terminal 22a) so as
to activate High temperature mode only when the temperature
at the furnace wall has exceeded 750°C. The PFU starts the
burner as usual, without monitoring the presence of the flame.
00
02
03
tZ
tFS
04
88
30a
26e
10e ϑ
28c
22a DI
16c V1
26a
2c–4c
18e V2
2e–4e
t
tSA
If the temperature in the furnace chamber drops below 750°C,
the DI input must be disconnected from the electrical power
supply and the furnace must be operated with the internal
flame control system.
t
Parameters > Flame control > High temperature operation with PFU..D
Parameter 33 = 2
The PFU then responds, depending on setting:
Parameter 33 = 1 (PFU 760..K2 only)
01 02
04
FA
tZ
tW
03
tFS
04
04
01 02
88
30a
26e
10e ϑ
28c
22a DI
16c V1
26a
2c–4c
18e V2
2e–4e
2a–4a
tZ
t
tW
03
tFS
04
88
30a
26e
10e ϑ
28c
22a DI
16c V1
26a
2c–4c
18e V2
2e–4e
2a–4a
t
tSA
tSA
If the flame fails during high temperature operation, the ready
contact opens for the duration of the flame failure (FA).
When High temperature mode is ended, the PFU switches off
the burner and restarts with flame simulation check (recommended in the case of UV control with UVS).
When High temperature mode is ended, the PFU switches off
the burner and restarts with flame simulation check (recommended in the case of UV control with UVS).
On programming parameter 33, ensure that the program
sequence matches the application. Select the parameters so
that the burner can be operated as intended in all operating
phases.
t
PFU 760 · Edition 05.11
22
Parameters > Flame control > High temperature operation with PFU..D
Parameter 33 = 3
04
04
Parameter 33 = 4 (PFU 760..K2 only)
88
30a
26e
10e ϑ
28c
22a DI
16c V1
26a
2c–4c
18e V2
2e–4e
t
When High temperature mode is ended, the burner remains
in operation and the PFU performs flame control again
­(recommended in the case of ionization control or UV control
with UVD).
If no flame signal is present when High temperature mode
is ended, the burner control unit performs a fault lock-out,
regardless of parameter 33.
04
04
PFU 760 · Edition 05.11
23
88
30a
26e
10e ϑ
28c
22a DI
16c V1
26a
2c–4c
18e V2
2e–4e
t
04
04
FA
88
30a
26e
10e ϑ
28c
22a DI
16c V1
26a
2c–4c
18e V2
2e–4e
2a–4a
t
If the flame fails during high temperature operation, the ready
contact is opened for the duration of the flame failure.
When High temperature mode is ended, the burner remains
in operation and the PFU performs flame control again
­(recommended in the case of ionization control or UV control
with UVD).
Parameters > Flame control
4.2.5 UVS check
Parameter 35
An automatic restart of the burner control unit can be activated
every 24 hours via this parameter. The time starts each time
the start-up signal (ϑ) is applied.
Parameter 35 = 0: Unlimited burner operation.
Parameter 35 = 1: An automatic restart is activated once every
24 hours.
It must be ensured in this case that the program sequence
started matches the application. This parameter may be set
in this way only if the burner can restart as intended in all
operating phases.
PFU 760 · Edition 05.11
24
Parameters
25
4.3 Behaviour in start-up position/standby
4.3.1 Flame simulation check in start-up position/standby
Parameter 15
This defines the instant for the flame simulation check.
00
01 02 . . .
88
00
01 02 . . .
tW
88
t
V1
02 . . .
V1
88
t
V1
t
Parameter 15 = 1: The flame simulation check is conducted
provided no start-up signal (ϑ) is applied (during the so-called
start-up position/standby). This allows fast start-up of the
burner since there is no waiting time tW.
The burner must have been switched off for at least 4 s before start-up in order for the flame simulation check to be
conducted correctly.
PFU 760 · Edition 05.11
00
01
V1
tW simulation checkt is conducted
Parameter 15 = 0: The flame
after applying00the start-up signal (ϑ) during
02 . . . the88waiting time tW.
00
What is an extraneous signal?
tLV
88
30a
26e
10e ϑ
28c
26a
16c V1
18e V2
2c–4c
2e–4e
t
An extraneous signal is an incorrect signal which is detected as
a flame signal out of sequence. If the PFU 760 notices such an
extraneous signal during the flame simulation check, it starts
the flame simulation delay time tLV. If the extraneous signal
is discontinued during this period, the burner can start up.
Otherwise, a fault lock-out occurs. 01 blinks on the display.
The flame simulation check of the burner is active until valve
V1 is enabled.
Parameters > Behaviour in start-up position/standby
4.3.2 Minimum burner pause time tBP
Parameter 21
Programmable time between 0 and 250 s.
04 00 01 02
tBP
03
tZ
tFS
04
88
1
5
4 ϑ
7
9
12 V1
14 V2
16-17
18-19
t
tSA
An immediate restart of the main burner after a controlled
shut-down, a start-up attempt, restart, cooling or purging
is prevented by the pause time. The pause time starts when
the air valve is switched off. If a start-up signal (ϑ) is applied
before expiry of this time, the start-up is delayed until the end
of the pause time.
After the pause time, the burner is started if the start-up signal
(ϑ) is applied.
The minimum burner pause time tBP serves to adapt the program sequence to the requirements of the application.
The time should be set such that the system can be moved to
ignition position, i.e. butterfly valves can be closed and, possibly, gas can be flared off, before a restart occurs.
See examples of application Staged On/Off burner control,
Staged High/Low burner control oder Two-stage-controlled
burner.
PFU 760 · Edition 05.11
26
Parameters
27
4.4 Behaviour during start-up
4.4.1 Safety time on start-up tSA
Parameter 22
00
02
03
tZ
04
88
30a
26e
10e ϑ
28c
26a
16c V1
18e V2
2c–4c
2e–4e
t
tFS
tSA
Safety time on start-up tSA for the burner.
4.4.2 Flame proving period tFS
Parameter 23
00
02
03
tZ
tFS
04
88
30a
26e
10e ϑ
28c
26a
16c V1
18e V2
2c–4c
2e–4e
t
tSA
Programmable time between 0 and 25 s.
This time elapses before the PFU starts the next program step
so as to give the flame time to stabilize.
PFU 760 · Edition 05.11
4.4.3 Minimum combustion time tB
Parameter 20
Programmable time in the range from minimum safety time
start-up tSA to maximum 25 s during which the burner remains
in operation.
In the case of brief activation of the start-up signal input (ϑ)
(e.g. with a pulse), the combustion time tB is started, and the
burner remains in operation for at least this period.
Parameters > Behaviour during start-up
28
4.4.4 Burner start-up attempts
Parameter 10
This indicates the number of possible start-up attempts of
the burner.
In accordance with EN 746-2, three start-ups are permitted in
specific cases in the event of flame failure during start-up, if
the safety of the installation is not impaired. Note the requirements of the Standards!
If no flame is detected during start-up, either a fault lock-out
is performed or further start-up attempts in accordance with
EN 746-2 occur.
Pursuant to NFPA 86, only one start-up attempt is permitted in
the event of flame failure during start-up. For units approved
by FM Approval (see type label), it is only possible to select
one start-up attempt.
1 start-up attempt
Parameter 10 = 1
00
02
02
88
30a
26e
10e ϑ1
28c
26a
16c V1
18e V2
2c–4c
2e–4e
t
tZ
t SA
If no flame forms during start-up, a fault lock-out is performed
after expiry of time tSA. The display blinks and shows the cause
of the fault.
PFU 760 · Edition 05.11
2 or 3 start-up attempts
Parameter 10 = 2, 3
00
88
30a
26e
10e ϑ
28c
26a
16c V1
18e V2
2c–4c
2e–4e
t
02
tZ
tZ
tSA
tSA
If several start-up attempts are set and if the PFU detects a
flame failure during start-up, it closes valve V1 after the safety
time tSA has expired and attempts to start up again. After the
last programmed start-up attempt has been completed, the
burner control unit conducts a fault lock-out. The display blinks
and shows the cause of the fault.
Parameters
4.5 Behaviour during operation
4.5.1 Safety time during operation tSB for V1 and V2
Parameter 14
This indicates the safety time during operation tSB for valves V1
and V2. The default in accordance with EN 298 is 1 s. The PFU
has also the available option of a safety time during ­operation
tSB of 2 s. Prolonging the time increases the installation availability in the case of brief-duration signal fades (e.g. fades of
the flame signal). In accordance with EN 746-2, the safety time
of the installation during operation (including closing time of
the valves) may not exceed 3 seconds (note the requirements
of the Standards).
29
4.5.2 Fault lock-out or restart
Parameter 12
This parameter determines whether the PFU starts a one-off
restart or performs an immediate fault lock-out for the burner
after a flame failure (see also Project planning information).
Immediate fault lock-out following flame failure
Parameter 12 = 0:
04
04
tSB
88
30a
26e
10e ϑ
28c
26a
16c V1
18e V2
2c–4c
2e–4e
t
After a fault lock-out, the burner control unit can be reset,
either with the button on the front panel or using an external
button. Several burner control units can be reset in parallel
using the external button.
The PFU cannot be reset by mains failure. The fault signalling
contact does, however, open as soon as the mains voltage fails.
See also parameter 32, Behaviour of the air valve in the event
of a fault lock-out.
t
PFU 760 · Edition 05.11
Parameters > Behaviour during operation > Fault lock-out or restart
Restart following flame failure
Parameter 12 = 1:
Restart following flame failure.
1x
04
01
03
>2 s
tSB
tFS
tZ
tW
04
88
30a
26e
10e ϑ
28c
26a
16c V1
2c–4c
2e–4e
t
tSA
If the PFU detects a flame failure after a minimum operating
time of 2 s, the valves are closed and the operation signalling
contact is opened within time tSB.
The burner control unit now attempts to restart the burner
once. If the burner does not function, a fault lock-out occurs.
The display blinks and shows the cause of the fault.
In accordance with EN 746-2, a restart may be conducted
only if the safety of the installation is not impaired. Restart is
recommended for burners which occasionally display unstable
behaviour during operation.
The precondition for a restart 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.
PFU 760 · Edition 05.11
30
Parameters
31
4.6 Switchable gas valve V2 on PFU..L
Parameter 26
Parameter 26 = 0: Gas valve V2 opens with the operating
signal.
Parameter 26 = 1: Gas valve V2 opens with the air valve ­during
operation
L1, N, PE
P
DI
SPS
PLC
API
22a 10c 26e
ϑ1
A
P
DI
PFU 760L
30e
10a
10e
µC
22e
18e 16c
28c
2e
4e
2c
4c
26a
TZI
VBY
VAG
4
7
M
BVA + IC 40
A switchable gas solenoid valve V2 can be activated with the
PFU..L. If Parameter 26 is set to 1, gas valve V2 can be activated
synchronously with the air valve during operation via the input
for the external activation of the air valve (terminals 10a/12a).
PFU 760 · Edition 05.11
Parameters
4.7 Air valve control PFU..L
Parameter 30, Behaviour of the air valve during operation
Parameter 31, Behaviour of the air valve during start-up
Parameter 32, Behaviour of the air valve in the event of a
fault lock-out
The PFU..L features an adjustable air valve control. The display
shows that purging is currently being carried out with P 0 .
A indicates that the air valve is being activated for cooling
or heating.
The PFU..L supports the following functions:
– Purge
– Cooling in start-up position/standby
– Switching of the burner between low and high burner
­output during operation via the air valve
– To start up the burner as intended, external activation of
the air valve can be blocked during start-up (prevents
synchronization problems between the PFU and the
­central control system).
– Controlling the air valve so that it
– opens with valve V1
– opens with valve V2
– Low fire over run time tKN after a controlled shut-down
PFU 760 · Edition 05.11
32
4.7.1 Purge
Parameter 42 = 0: The air valve is closed when voltage is
applied to terminal 30e.
Parameter 42 = 1: The air valve is opened when voltage is
applied to terminal 30e.
In the case of multiple burner applications, burners with
­mechanical combustion air supply are used. The air for combustion and pre-purge is supplied by a central fan controlled
by a separate logic. This logic determines the purging time.
The PFU..L supports centrally-controlled pre-purge or postpurge. The PFU..L is informed that purging is currently being
performed by input 30e. It then opens the air valve, regardless of the status of the other inputs (purging has priority). The
display indicates P 0 .
4.7.2 Cooling in start-up position/standby
The air valve can be activated externally via input 10a for cooling in the start-up position. During activation of the air valve
the display shows A 0 , indicating that cooling is currently
being carried out.
4.7.3 Burner start
Parameters 30 and 31 determine the behaviour of the air valve
during burner start.
Parameters > Air valve control PFU..L
33
4.7.4 Air valve opens in the case of external activation (not
during start-up)
00
A0
02
03 A4
tZ
88
30a
26e
10e ϑ
28c
26a
16c V1
18e V2
10a A
22e
2c–4c
2e–4e
t
tFS
tSA
L1
ϑ
PFU 760L
A
SPS
PLC
API
P
TZI
GIK..B
VAS..N
VR..R
PFU 760 · Edition 05.11
Parameter 30 = 0: The air valve opens if it is activated externally by input 10a.
Parameter 31 = 0: The air valve remains closed during start-up
even if it is activated externally.
These settings are required on burners on which the gas/air
ratio is controlled by a pneumatic ratio control system and
which also need to be started at low fire, e.g. on two-stagecontrolled burners. In this case, activation of the air valve during
burner start via input 10a must be prevented.
External control allows switchover between low fire and high
fire during operation.
The air valve can be activated externally via input 10a for cooling the burner in the start-up position/standby.
Parameters > Air valve control PFU..L
34
4.7.5 Air valve opens in the case of external activation (even
during start-up)
00 A0 00 A0 A2
A3 A4
tZ
tFS
tSA
L1
ϑ
PFU 760L
A
SPS
PLC
API
P
TZI
EKO
VG..L
GEH
BICR
VR..R
LEH
PFU 760 · Edition 05.11
EKO
88
30a
26e
10e ϑ1
28c
26a
16c V1
18e V2
10a A
22e
2c–4c
2e–4e
t
Parameter 30 = 0: The air valve opens if it is activated externally via input 10a.
Parameter 31 = 1: The air valve can be activated even during
start-up.
These settings may be selected only if the burner can start
with full air capacity.
The air valve can be activated externally via input 10a for cooling the burner in the start-up position/standby.
Parameters > Air valve control PFU..L
35
4.7.6 Air valve opens with valve V1
00 A0 00 A0 A2
A3 A4
tZ
tFS
tSA
L1
ϑ
PFU 760L
A
SPS
PLC
API
P
TZI
EKO
VG..L
GEH
BICR
VR..R
LEH
PFU 760 · Edition 05.11
EKO
88
30a
26e
10e ϑ1
28c
26a
16c V1
18e V2
10a A
22e
2c–4c
2e–4e
t
Parameter 30 = 1:
The air valve opens simultaneously with valve V1.
Application: Single-stage-controlled burner is switched
ON/OFF via the ϑ input.
The air valve can be activated externally via input 10a for cooling the burner in the start-up position/standby.
Parameters > Air valve control PFU..L
36
4.7.7 Air valve opens with valve V2
00 A0 00
02
03 A4
tZ
88
30a
26e
10e ϑ
28c
26a
16c V1
18e V2
10a A
22e
2c–4c
2e–4e
t
tFS
tSA
L1
ϑ
PFU 760L
A
SPS
PLC
API
P
TZI
UV
VAG
VR..R
PFU 760 · Edition 05.11
Parameter 30 = 2:
The air valve opens simultaneously with valve V2.
Application: Two-stage-controlled burner is switched ON/OFF
via the ϑ input.
The air valve can be activated externally via input 10a for cooling the burner in the start-up position/standby.
Parameters > Air valve control PFU..L
37
4.7.8 Low fire over run time tKN after a controlled shut-down
A4
00
tKN
L1
ϑ
88
30a
26e
10e ϑ
28c
16c V1
26a
2c–4c
18e V2
22e
2e–4e
t
PFU 760L
A
SPS
PLC
API
P
TZI
UV
VAG
VR..R
PFU 760 · Edition 05.11
Parameter 36
Settings: 0; 3; 5; 10; 15; 25 or 60 (low fire over run time in
seconds)
This parameter is applicable to systems with a pneumatic ratio
control system and On/Off control.
Parameter 36 = 0 (low fire over run time tKN = 0 s): Without low
fire over run, the gas side is closed immediately owing to the
quick-closing gas valve in the case of On/Off control. The air
side closes more slowly. The air flowing in during the closing
time increases the O2 content in the combustion chamber.
Parameter 36 = 3; 5; 10; 15; 25 or 60 (low fire over run time
tKN = 3, 5, 10, 15, 25 or 60 s):
The air valve closes slowly after the activation signal has been
switched off. The gas valve remains open for tKN. This means
that the burner, after deactivation of the start-up signal (ϑ),
is initially adjusted down to low fire and then switched off
completely.
Using the low fire over run function reduces the O2 content in
the furnace atmosphere.
Flame control is still operational. Can be used only in the case
of a pneumatic air/gas ratio control system and On/Off control.
Its must be ensured that no excess gas occurs.
Parameters > Air valve control PFU..L
4.7.9 Behaviour of the air valve in the event of a fault lock-out
Parameter 32
This determines whether the air valve can be activated in the
case of a fault lock-out.
Parameter 32 = 0:
The air valve is closed in the event of a fault. It cannot be
activated externally via terminal 10a.
Parameter 32 = 1:
The air valve can be activated externally via input 10a even
during a fault, e.g. for cooling.
PFU 760 · Edition 05.11
38
Parameters
4.8 Manual operation
For convenient setting of the burner or analyzing faults.
The parameter display is not available in Manual mode.
­Manual mode can be accessed only if the unit was not in
Fault state before switching off. The following times/functions
are not active in Manual mode: start-up attempts, restart,
minimum combustion time and cycle lock.
If the Reset/Information button is pressed for 2 s during switchon, the PFU reverts to Manual mode. Two dots blink on the
display.
In this operating mode, the burner control unit operates independently of the status of the inputs (apart from the pre-purge
input and the safety interlocks. These are of higher priority and
will be processed first).
Each time after the button is pressed again, the PFU moves
to the next section of the program sequence and stops there.
After approx. 3 s, the flame signal will be displayed instead of
the program parameter. Briefly pressing the Reset/Information button (< 1 s) displays the relevant Manual mode step. If
there is flame simulation during the start-up, the flame signal
is displayed immediately.
On units with air valve control, the air valve can be opened
and closed repeatedly by pressing the button during operation.
Manual mode can be terminated by switching off the PFU
(On/Off button).
PFU 760 · Edition 05.11
39
4.8.1 Manual mode limited to 5 minutes
Parameter 34
Parameter 34 determines when Manual mode is terminated.
Parameter 34 = 0: Manual mode is not limited in time. If this
function has been selected, operation of the furnace may
be continued manually in the event of failure of the central
control system.
Parameter 34 = 1: Manual mode ends automatically five
­minutes after the last time the button was pressed. The PFU
then moves abruptly back to start-up position/standby.
4.9 Password
Parameter 50
(Four-digit) password saved to protect parameter settings.
To prevent unauthorized changes to parameter settings, a
password is stored in parameter 50. Changes to parameter
settings can only be made once this number has been entered.
The password can be changed using BCSoft.
Note the effect of parameter settings on the safe functioning
of your system.
The password set at the factory can be found in the delivery
note supplied.
Parameters
40
4.10 Multi-flame control
Parameter 45
(
30a
N
32c
L1 (L1)
30e
26a
20c
24c
2a
230V
1
2 UVS
3
2e
Z
L1
N
N
1
2 UVS
3
8e
N
N
18a
230V
18e
Z
N
N
24e
24a
30e
L1
Z
1
2 UVS
3
24e
N
N
L1
Z
10c
PFF 704
2e
s 4e
N
I
2c
m 4c
26a
20c
8a
8c
8e
0V
24 V
28e
ϑ1
10e
12e
0V
A
26c
Parameter 45 = 0: Multi-flame control is switched off.
Parameter 45 = 1: Multi-flame control is switched on. The
parameter must be set to 1 to ensure that the flames are
monitored.
PFU 760 · Edition 05.11
2a
a 4a
22a
28a
10a
12a
24 V
V1
V2
28c
26e
I
16c
18e
32c
24c
20c
230 V
12a
22e
24a
230V
sk1
30a
N (L2)
Z
N
22e
22a
N
28c
20e
I
L1
Z
DI
12e
1
2 UVS
3
30e
F1
10e
I
L1
18e
18a
30e
L1
Z
PFU 760L)
PFU 760
26e
4c
6e
8a
230V
Z
3
4e
I
L1
8e
8a
30e
L1
Z
1
UVS 2
6a
P
10c
12c
A
µC
S
SK
max. 1 A, 24 V
2e
2a
30e
L1
41
5 Selection
5.1 Safety time
Please quote the safety time tSA when ordering.
EN 746-2
t SA
PN
≤ 70 kW
5s
> 70 kW*
3s
≤ 350 kW
10 s
5s
> 350 kW**
0 ➔ ∞*
10 s
* P Z 0,1 x P N , P Zmax = 350 kW
** P Z 0,33 x P N , P Zmax = 350 kW
tSA = 3 s, 5 s or 10 s
PN = Rated heat output
PZ = Ignition capacity
The safety time of the burner control unit depends on the
burner type, the burner output and the respective application.
PFU 760 · Edition 05.11
5.1.1 Calculating the safety time tSA
Burner with mechanical
combustion air supply
Natural draught burner with direct ignition
Natural draught burner with pilot burner
Burner output
Safety time
on start-up tSA
1.00 kW
3 s
Ignition burner input rating at a level of 10 % of nominal
heat input with a maximum of 350 kW.
Selection
42
5.2 Selection table
Type
PFU 760
L*

T

5.3 Type code
N

* If “none”, this specification is omitted.
 = standard,  = available
Order example
PFU 760LT
D*

U*

K1*

K2*

Code
L*
T
N
D*
U*
K1*
K2*
Description
Air valve control
Mains voltage
220 – 240 V AC, -15/+10%, 50/60 Hz
110 – 120 V AC, -15/+10%, 50/60 Hz
Digital input to interrupt flame control
Preparation for UV sensor for continuous operation UVD 1
Compatible with PFS/PFD
PFU 778
* If “none”, this specification is omitted.
PFU 760 · Edition 05.11
43
6 Project planning information
6.1 Cable selection
Use mains cable suitable for the type of operation and complying with local regulations. Do not route PFU cables in the
same cable duct as frequency converter cables or cables
emitting strong fields.
6.1.1 Ignition cable
Use unscreened high-voltage cable see page 49 (Accessories).
Cable length: max. 5 m, recommended < 1 m. Screw the ignition cable securely into the ignition transformer and run to the
burner by the shortest possible route.
The longer the ignition cable, the lower the ignition capacity.
Only use radio interference suppressed electrode adapters
(with 1 kΩ resistor) for ignition electrodes see page 49 (Accessories). Do not lay UV/ionization cable and ignition cables
together and lay them as far apart as possible.
6.1.2 Ionization cable
Use unscreened high-voltage cable see page 49 (Accessories).
­Cable length: max. 100 m. Avoid external electrical interference. Install as far as possible from mains and ignition cables
and interference from electro-magnetic sources. If possible,
do not lay in a metal conduit. Several ionization cables can
be routed together.
PFU 760 · Edition 05.11
6.1.3 UV cable
Cable length: max. 100 m. Avoid external electrical interference.
Install as far as possible from mains and ignition cables and
interference from electro-magnetic sources. If possible, do
not lay in a metal conduit. Several UV cables can be routed
together.
6.2 Ignition electrode
6.2.1 Electrode gap
Gap between electrode and burner ground:
2 mm ± 0.5 mm.
6.2.2 Star electrodes
We recommend using 7.5 kV ignition transformers on burners
with star electrodes.
Project planning information
6.3 Minimum combustion time
Even if the start-up signal (ϑ) is applied only briefly, the time
set under parameter 20 elapses before the burner control
unit shuts down the burner or signals a fault.
The minimum combustion time tB can be extended beyond
the safety time tSA to max. 25 s.
6.4 Safety interlocks (Limits)
The limiters in the safety interlock (linking of all the relevant
safety control and switching equipment for the use of the
application, e.g. safety temperature limiter, minimum and
maximum gas pressure, tightness control) must isolate terminal 26e from the voltage supply. If the safety interlock is
interrupted, this is indicated by a blinking 51 on the display.
If the safety interlocks fail, an immediate program abort with
switch-off of all outputs occurs (even during the safety time).
If the safety interlocks are operational again or the unit is
switched back on, the program run is restarted in standby.
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.
PFU 760 · Edition 05.11
44
Project planning information
6.6 Reset
6.6.1 Parallel reset
Several burner control units can be reset in parallel using 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, 52
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, error 10
(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 malfunction
can not be remedied by changing the method of activation.
PFU 760 · Edition 05.11
45
6.6.4 Burner start
A furnace start may only be initiated, if it has been ensured
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 before ignition or within the period specified in the operating instructions.
In the case of multiple burner applications, pre-purge is not
necessary after a controlled 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.
Project planning information
46
6.7 Fault signalling
6.9 Installation
The fault signalling contact opens, as soon as the mains voltage fails.
Installation position: any.
Installation in 19" module subracks only, see page 50 (Module
subracks).
Install in clean environment ensuring enclosure IP 54 or higher,
whereby no condensation is permitted.
Cable length between PFU and burner: max. 100 m.
6.8 Protecting the burner from overload
To protect the unit against overload by frequent cycling, the
maximum number of start-ups per minute is limited for the
PFU. Excessive cycling triggers a fault message (blinking 53 ).
The max. number of start-ups per minute depends on the
safety time tSA:
tSA [s]
3
5
10
Ignition transformer TZI
5-15/100
5-15/100
5-15/100
Max. start-ups/min.
6
5
4
6.10 Wiring
The PFU is suitable for hard wiring only. Do not reverse phase
and neutral conductor. Different phases of a three-phase
­current system must not be installed at the PFU. No voltage
may be connected to the valve and ignition outputs.
6.10.1 UVS sensor wiring
Connect the UVS sensor directly to the PFU. Operating the
sensor with incorrect polarity or voltage can lead to destruction of the sensor.
6.11 PFU switched off
The PFU cannot be activated when no mains voltage is applied
or when it 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.
PFU 760 · Edition 05.11
Project planning information
47
6.12 Furnace control
6.15 Changing parameters
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.
In certain cases, it may be necessary to change the default
settings. Using a separate software package and a PC optoadapter, it is possible to modify certain parameters on the PFU,
such as the switch-off threshold of the flame amplifier or the
behaviour in the event of a flame failure.
The software package with PC opto-adapter, as well as
“Changed parameters” stickers, are available as accessories – see section entitled “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.
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 501561:2004 (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 by removing the unit or with an
external switch per unit or group only, in accordance with
Standard EN 50156.
PFU 760 · Edition 05.11
48
7 Flame control
7.1 With ionization sensor
The PFU generates an alternating voltage (230 V AC) between
the sensing electrode and burner ground. The flame rectifies
this voltage. Only the DC signal (depending on the switch-off
threshold) is recognized by the burner control unit as a flame
signal.
A flame cannot be simulated. Ignition and monitoring with a
single electrode is possible.
7.2 With UV sensor
A UV tube inside the UV sensor detects the ultraviolet light of
a flame. It does not respond to sunlight, incandescent bulb
light or infrared radiation emitted by hot workpieces or redhot furnace walls.
In the event of incident UV radiation the UV sensor rectifies
the supplied alternating voltage. As with ionization control,
the burner control unit only detects this DC signal.
When using UV sensors of Type UVS, the burner control unit
may be used for intermittent operation only. This means that
operation must be interrupted at least once every 24 hours.
This can be programmed using parameter 35.
For further information, see brochure UVS.
The burner control unit PFU..U is prepared for UV sensor UVD 1.
This enables continuous operation. For further information, see
Technical Information Bulletin UVD.
PFU 760 · Edition 05.11
7.3 Via the temperature in high temperature
equipment
High temperature equipment is defined as a thermoprocessing
installation, in which the wall temperature of the combustion
chamber and/or the processing chamber exceeds 750°C.
Burner control unit PFU..D features a special “High temperature
operation” function. During heating up, standard monitoring
methods (ionization or UV) must be used for flame control.
When the working temperature has exceeded 750°C, indirect
flame control can be taken over by a central monitoring device.
When the DI input (terminal 22a) is activated, the burner control
unit reverts to this operating mode.
Important: In “High temperature operation”, i.e. with the DI
input being activated, burner control unit PFU..D does not
evaluate the flame signal. The safety function of the burner
control unit’s flame control is deactivated during this operating phase.
49
8 Accessories
8.3 Stickers for labelling
For printing with laser printers, plotters or engraving
machines, 27 × 18 mm or
28 × 17.5 mm.
Colour: silver
8.1 High-voltage cable
FZLSi 1/7 up to 180°C,
Order No.: 04250410.
FZLK 1/7 up to 80°C,
Order No.: 04250409.
Brenner
Zone 3
1
8.2 BCSoft
8.4 “Changed parameters” stickers
D-49018 Osnabrück, Germany
Achtung, geänderte Parameter!
Die Angaben auf dem Typenschild
gelten nicht mehr in vollem Umfang.
Aktuelle Parameter direkt auslesen.
Opto-adapter including BCSoft CD-ROM,
Order No.: 74960437.
The current software can be downloaded from our Internet site at
www.docuthek.com. To do so, you need to register in the
DOCUTHEK.
PFU 760 · Edition 05.11
Important, changed parameters!
The details on the type label are no
longer completely accurate. Read the
current parameters direct from the
unit.
Attention, paramètres modifiés !
Les informations figurant sur la plaque
signalétique ne sont plus valables
dans leur intégralité. Veuillez vous
référer directement aux paramètres
actualisés.
Affix on the connection diagram of
the PFU following changes to unit
parameters set at the factory.
100 pcs,
Order No.: 74921492.
Accessories
8.5 Radio interference suppressed electrode adapters
Plug cap, 4 mm, interference-suppressed,
Order No. 04115308.
Straight adapter, 6 mm, interference-suppressed,
Order No. 04115306.
8.6 Socket connectors
Type
Order No.
Socket connector E, 48-pin solder tag connection 04120148
Socket connector E, 48-pin wire-wrap connection 04120158
8.7 Module subracks
Module subracks BGT S-9U/1 for PFP 700, PFU 760
comprising: module subrack, printed-circuit board with rear
terminal strip, function-tested, standard documentation, guide
rails, without partial front plates, screw terminals at the rear.
Slots 1–9 for PFU 760, slot 10 for PFP 700
Order No. 84402281.
PFU 760 · Edition 05.11
50
Module subrack BGT SM-8/1/1 for MPT 700, PFU 760
comprising: module subrack, printed-circuit board with rear
terminal strip, function-tested, standard documentation, guide
rails, without partial front plates, screw terminals at the rear,
single-zone operation for MPT 700 operating modes 1-4, twozone operation for MPT 700 operating modes 1-4, but max.
4 burners per zone.
Slot 1 for MPT 700, slots 2–9 for PFU 760, slot 10 for PFP 700
Order No. 84402282 (no illustration provided).
Module subrack BGT SA-9U/1DP for PFA 700, PFU 760
comprising: module subrack, printed-circuit board with rear
terminal strip, function-tested, standard documentation, guide
rails, without partial front plates, screw terminals at the rear,
relays and screw terminals for four free inputs and four free
outputs.
Slot 1 for PFA 700, slots 2–10 for PFU 778 without digital input,
connection to PROFIBUS-DP with D-Sub socket.
Order No. 84402283 (no illustration provided).
Accessories
51
8.8 Power supply PFP 700
For supplying the control inputs of burner control unit PFU or
for supplying the auxiliary voltage to relay module PFR 704.
Operating status display on the front plate. PFP switches off
in the event of an output overload.
Output voltage 24 V, output rating 14 VA.
PFP 700
L1
30a
N
32c
F1
S0
S1
O
115 V
8ace
I
12ace
U
PFU 760 · Edition 05.11
230 V
I
24 V=
600 mA
0V
Accessories
52
8.9 Relay module PFR 704
For contact multiplication, e.g. if several air valves are activated
via one control signal for pre-purge, or for heating/cooling
switchover when using an MPT. Switching status display on
the front plate.
Input voltage:
110/120 V AC, -15/+10%, 50/60 Hz,
220/240 V AC, -15/+10%, 50/60 Hz,
24 V AC/DC, ± 10%.
Current per relay: 25 mA.
Contact rating of floating outputs: max. 2 A, 264 V (not fused
internally).
8a
8e
0V
4e
8c
6c
230 V~
115 V~
24 V=/~
10e
10a
10c
16a
16e
2
14a
14e
0V
12e
14c
16c
230 V~
115 V~
24 V=/~
18e
18a
18c
24a
24e
3
0V
20e
230 V~
115 V~
24 V=/~
26e
26a
26c
PFU 760 · Edition 05.11
28e
22c
24c
32a
32e
4
0V
22a
22e
30a
30e
30c
32c
max. 2 A, 264 V
1
max. 2 A, 264 V
6a
6e
max. 2 A, 264 V
2e
2a
2c
max. 2 A, 264 V
PFR 704
230 V~
115 V~
24 V=/~
Accessories
53
8.10 Flame detector PFF 704
For flame detection or multi-flame control in conjunction with
PFU, with 4 independent flame detectors. For intermittent operation with ionization or UV control.
Power consumption: 10 VA.
Ionization voltage: 230 V AC.
Max. flame signal cable length: 100 m.
Cut-off sensitivity of the flame amplifiers: adjustable between
1 µA and 10 µA (factory default setting: 1 µA).
Contact rating: max. 2 A.
Mains voltage: 110 – 240 V AC, 15/10%, 50/60 Hz.
Further information can be found in brochure PF 19”.
PFF 7x4
1
8a
230V
8e
1
2 UVS
3
Z
N
N
Z
18e
18a
30e
18a
230V
18e
N
N
1
2 UVS
3
Z
N
N
L1
PFU 760 · Edition 05.11
Z
F4
12e
20a
20c
P3
F6
F5 20e
22e
28a
28c
- +
26a
26c
I
4
F3 10e
22a
22c
- +
24a
230V
24e
6e
10a
10c
P2
3
4e
12a
12c
I
L1
L1
24e
24a
30e
Z
F2
- +
2
1
2 UVS
3
Z
P1
I
L1
L1
L1
F1
L1
8e
8a
30e
4a
4c
I
P4
F8
F7 26e
28e
max. 2 A, 264 V
N
N
L1
Z
6a
6c
- +
2e
Z
230 V
115 V
max. 2 A, 264 V
2a
230V
1
2 UVS
3
S1
max. 2 A, 264 V
2e
2a
30e
S0 O
I
max. 2 A, 264 V
30a
32c
30e
L1
N
P1–P4: PFF 704
Accessories
54
8.11 Field bus interface PFA 700
For connection of up to nine automatic burner control
units PFU 760 to industrial communication networks using
PROFIBUS-DP, in order to transfer measuring, control and
regulation signals as a bundle.
4 digital inputs:
24 V DC, ± 10%, < 10 mA,
4 digital outputs:
relay contact, max. 1 A, 264 V (not fused internally).
Mains voltage: 110 – 240 V AC, -15/+10%, 50/60 Hz.
Further information can be found in brochure PFA.
PFA 700
15b 24 V=
16b 0 V
18b
1a
9a
1
21b
4
22b
10a
…
24 V
24 V
23b
26b
18a
I/O
19a
1
23a
…
24 V
0V
4
20c
23c
19c
…
9. PFU
1. PFU
…
18c
1. PFU
9. PFU
1. PFU
…
2
…
…
24 V
9c
10c
PROFIBUS DP
8b
RxD/TxD-P 11b
RxD/TxD-N 12b
14b
DGND
VP
ϑ
9. PFU
1. PFU
…
1c
µC
9. PFU
1. PFU
…
N
5. PFU
6. PFU
…
32b
30a
L1
9. PFU
PFU
17b
1
L1
24 V
30c
30e
26e
PFU
PFU 760 · Edition 05.11
Accessories
55
8.12 Impulse system MPT 700
MPT 700
L1
30z
30b
30d
N
28z
28b
28d
PE
32z
32b
32d
mA
mA
1
GND
2
8888
88
18z
18b
18d
0 – 100%
GND
100% – 0
12–24 V
20z
20b
20d
F1
E1
E2
E3
0V
PFU 760 · Edition 05.11
14z
14d
16z
14b
16b
µC
2b
4b
12–24 V
10b
12b
0V
2z
A1
2d
A2
4z
A3
4d
A4
6z
A5
6d
A6
8z
A7
8d
A8
10z
/
1
10d
/
2
12z
6b
8b
COM
With 11 outputs for activation of burner control units PFU 780.
The furnace atmosphere is circulated thanks to intermittent
operation, and thereby constant temperature distribution and
shorter heating-up periods for all gas-fired heat treatment
furnaces are ensured.
Mains voltage: 95 – 240 V AC, ± 10%, 50/60 Hz.
Power consumption: 10 VA.
Additional auxiliary voltage: 12 – 24 V DC, ± 10%, max. 1.1 A.
Controller inputs: 2 x 0(4) – 20 mA with common ground, floating, load impedance approx. 225 Ω.
Three-point step input: floating, 12 – 24 V DC, load impedance
approx. 2.7 kΩ.
Digital inputs E1 – E3: with common ground, floating, 12 –
24 V DC, load impedance approx. 2.7 kΩ.
Further information can be found in brochure MPT.
56
9 Technical data
Output voltage for voltage-related outputs = mains voltage
Mains voltage:
220/240 V AC, -15/+10%, 50/60 Hz or
110/120 V AC, -15/+10%, 50/60 Hz,
for grounded and ungrounded mains.
Power consumption: < 8 VA.
Control inputs:
Input voltage/current:
Burner, air valve, multi-flame control and remote reset:
24 V DC, ± 10%, < 7 mA per input.
Input voltage for safety interlocks, digital input DI and purge
= mains voltage.
Input voltage of signal inputs:
Rated value
110/120 V AC
220/240 V AC
Signal “1”
80 – 132 V
160 – 264 V
Signal “0”
0 – 20 V
0 – 40 V
Frequency
50/60 Hz
50/60 Hz
Contact rating
Gas valve V1, V2
Max. 1 A resistive
Max. 1 A cos ϕ 0.3
Air valve
Max. 1 A resistive
Max. 1 A cos ϕ 0.3
Ignition
Number of operating cycles
Max. 1 A resistive
Max. 1,000,000,
­typically 400,000
Max. 1 A cos ϕ 0.3
Max. 250,000,
­typically 100,000
Rated value
Signal “1”
Signal “0”
Inherent current:
Signal “1”
PFU 760 · Edition 05.11
24 V DC
24 V, ±10%
<1V
typ. 5 mA
Output current: max. 2 A per output, but total current for valves
and ignition transformer max. 2.5 A.
Number of operating cycles:
Mains switch: 1000,
Reset/Information button: 1000.
t
Technical data
Signalling contacts:
max. 24 V, 1 A.
Flame control:
Sensor voltage: approx. 230 V AC.
Sensor current: > 1 μA,
Length of sensor cable: max. 100 m.
Fuse in unit:
F1: 3.15 A, slow-acting, H pursuant to IEC 127-2/5,
F2: 3.15 A, slow-acting, H pursuant to IEC 127-2/5.
Ambient temperature:
-20 to +60°C (-4 to +140°F),
Climate: no condensation permitted.
Enclosure: IP 00 pursuant to IEC 529,
after installing in a 19" module subrack according to the instructions, e.g. type BGT, the front corresponds to IP 20.
Input/Output safety circuit:
All the inputs and outputs marked “ ” (see connection diagrams) may be used for safety tasks.
Weight: approx. 650 g (23 oz)
PFU 760 · Edition 05.11
57
Technical data
58
9.1 Safety-specific characteristic values
In the case of ionization
control, suitable for Safety
Integrity Level
Diagnostic coverage DC
Type of subsystem
Mode of operation
Mean probability of dangerous failure PFHD
Mean time to dangerous
failure MTTFd
Safe failure fraction SFF
SIL 3
97.9%
Type B to EN 61508-2,
7.4.3.1.4
High demand mode pursuant to EN 61508-4, 3.5.12
1.34 x 10-8 l/h
99.2%
The specified values apply for the combination with ionization
electrode (sensor) and PFU 760 (logic).
Relationship between the Performance Level (PL) and the
Safety Integrity Level (SIL)
PL
SIL
a
–
b
1
c
1
d
2
e
3
Pursuant to EN ISO 13849-1:2006, Table 4, the PFU can be
used up to PL e.
PFU 760 · Edition 05.11
Max. service life under operating conditions:
20 years after date of production, plus max. 1/2 year in storage prior to first use.
For a glossary of terms, see page 62 (Glossary).
Technical data
59
9.2 Operating controls
A
B
00
C
F1
D
E
PFU 760 · Edition 05.11
F2
A: 2-digit 7-segment display
B: Reset/Information button to reset the system after a fault
or to scan parameters on the display.
C: Mains switch
D: Optical interface
E: Type label
60
10 Maintenance cycles
Burner control unit PFU requires little servicing.
PFU 760 · Edition 05.11
61
11 Legend
88 Display
88 Blinking display
Ready
Safety interlocks (Limits)
Burner start-up signal
DI
Digital input
Ignition transformer
Gas valve
Air valve
P
A
Purge
Ext. air valve control
Flame signal
1
Burner operating signal
Fault signal
Reset
Input signal
Output signal
Flame simulation check
tW Waiting time ≥ 2 s
tSA Safety time on start-up 3 s, 5 s or 10 s
tSB Safety time during operation < 1 s or < 2 s
tZ Ignition time 2 s, 3 s or 6 s
tLV Flame simulation delay time 25 s
tFS Flame proving period 0 – 25 s
tB Minimum combustion time tSA up to max. 25 s
tBP Minimum burner pause time 0 – 250 s
PFU 760 · Edition 05.11
tKN Low fire over run time 0 s, 5 s, 15 s or 25 s
Input/Output safety circuit
62
12 Glossary
12.4 Flame simulation/Flame simulation delay time
tLV
12.1 Waiting time tW
01 02
tW
02
30e
10e
28c
16c
26a
18e
2c–4c
2e–4e
tZ
01
01
88
L1
ϑ
V1
V2
tW
t
30e
10e
28c
16c
26a
18e
2c–4c
2e–4e
88
L1
ϑ
V1
V2
t
tLV
tSA
Once the start-up signal ϑ has been applied, the waiting time
tW starts to elapse. During this time, a self-test is conducted
to detect errors in internal and external circuit components. If
no malfunction is detected, the burner will start up.
12.2 Safety time on start-up tSA
This refers to the period of time between switching on and
switching off of the gas valve, when no flame signal is detected.
The safety time on start-up tSA (3, 5 or 10 s) is the minimum
operating time of the burner and burner control unit.
An extraneous signal (flame simulation) is a flame signal that
is detected, although there should be no flame according
to the program sequence. If such an extraneous signal is
­detected, the flame simulation delay time tLV starts to elapse.
If the flame simulation is discontinued during the flame simulation ­delay time tLV, start-up can be initiated or operation
continued. ­Otherwise, a fault lock-out occurs.
12.5 Safety time during operation tSB
04
04
12.3 Ignition time tZ
If no malfunction is detected during the waiting time tW, the
ignition time tZ then starts to elapse. Voltage is supplied to
the pilot gas valve V1 and the ignition transformer and the
burner is ignited. The duration of the ignition time is either 2,
3 or 7 seconds (depending on safety time tSA selected).
tSB
30e
10e
28c
16c
26a
18e
2c–4c
2e–4e
88
L1
ϑ
V1
V2
t
If the flame fails during operation, the valve outputs are disconnected within the safety time tSB.
t
PFU 760 · Edition 05.11
Glossary
12.10 Main gas valve V2
Once the safety time on start-up tSA has elapsed, the main
gas valve V2 is opened. It remains open until the burner is
switched off or a fault is signalled.
12.6 Flame signal
If a flame is detected, the flame detector will supply a flame
signal.
(
P
L1 (L1)
In the event of a fault lock-out, all valves and the ignition transformer are disconnected from the electrical power supply,
and a fault is signalled. Resetting must take place manually
following a fault lock-out.
DI
12.9 Pilot gas valve V1
The start fuel flow rate for the burner is released by pilot gas
valve V1. It opens when the safety time on start-up tSA starts to
elapse. It remains open until the burner is switched off again
by a normal shut-down or fault lock-out.
sk1
16c
18e
V1
V2
22a
30a
N (L2)
32c
24c
20c
230 V
12.11 Continuous 28c
operation
2a
a 4a
2e
s 4e
N
The gas
burner runs
continuously for more than
24 hours.
Z
2c
I
12.12 Air valve
26a
m 4c
PFF 704
The air valve can be used
A
8a
8a
24 Vcooling,
– for
8c
8c
S
µC
– for purging,
8e
8e
0V
SK
– to control theϑ1burner output in ON/OFF mode and in High/
10e
24 V
Low mode when using a pneumatic air/gas ratio control
12e
0V
system.
A
10a
12a
10c
12c
1
UVS 2
3
PFU 760 · Edition 05.11
N
22e
26e
12.8 Safety interlocks (Limits)
The limiters in the safety interlock (linking of all the relevant
safety control and switching equipment for the use of the
­application, e.g. safety temperature limiter, minimum/maximum gas pressure) must isolate input
from the voltage
supply.
PFU 760
30e
F1
12.7 Fault lock-out
PFU 760L)
max. 1 A, 24 V
The default safety time during operation tSB in accordance with
EN 298 is 1 second. In accordance with EN 746-2, the safety
time of the installation during operation (including closing time
of the valves) may not exceed 3 seconds (see “Project planning information”). Note the requirements of the Standards!
63
26a
20c
24c
Glossary
64
12.13 Diagnostic coverage DC
12.17 Mean time to dangerous failure MTTFd
Measure of the effectiveness of diagnostics, which may be
determined as the ratio between the failure rate of detected
dangerous failures and the failure rate of total dangerous
failures
NOTE: Diagnostic coverage can exist for the whole or parts
of a safety-related system. For example, diagnostic coverage could exist for sensors and/or logic system and/or final
elements. Unit: %.
Expectation of the mean time to dangerous failure
from EN ISO 13849-1:2008
from EN ISO 13849-1:2008
12.14 Mode of operation
High demand mode or continuous mode
Operating mode, where the frequency of demands for operation made on a safety-related system is greater than one per
year or greater than twice the proof-test frequency
from EN 61508-4:2001
12.15 Safe failure fraction SFF
Fraction of safe failures related to all failures, which are assumed to appear
from EN 13611/A2:2011
12.16 Probability of dangerous failure PFHD
Value describing the likelihood of dangerous failure per hour
of a component for high demand mode or continuous mode.
Unit: 1/h
from EN 13611/A2:2011
PFU 760 · Edition 05.11
65
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Kromschröder AG
Michael Rehkamp
m.rehkamp@kromschroeder.com
Osnabrück
(Adobe Reader 7 or higher required)
www.adobe.com
Elster GmbH
Postfach 2809 · 49018 Osnabrück
Strotheweg 1 · 49504 Lotte (Büren)
Germany
T +49 541 1214-0
F +49 541 1214-370
info@kromschroeder.com
www.kromschroeder.com
www.elster.com
PFU 760 · Edition 05.11
The current addresses of our international
agents are available on the Internet:
www.kromschroeder.de/index.php?id=718&L=1
We reserve the right to make technical
modifications in the interests of progress.
Copyright © 2007 – 2011 Elster Group
All rights reserved.
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