IFD 258 · Edition 10.09
35
Glossary
12 .5 Safety time during operation t
SB
tSB
t
1
3
10
11
5
L1
04
04
88
13–14
8–9
ϑ
If the flame fails during operation, the valves are closed within
the safety time t
SB
.
The default safety time during operation t
SB
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 – p. 26]. Note the requirements of the Standards!
12 .6 Flame signal
If a flame is detected, the flame detector will supply a flame
signal.
12 .7 Flame detector
The flame detector detects and signals the presence of a flame.
The flame detector usually consists of a flame sensor, an ampli-
fier and a relay to produce the signal. These components, with
the exception of the flame sensor itself, are accommodated
within a single housing (IFW 50).
12 .8 Fault lock-out
In the event of a fault lock-out, all valves are closed and a
fault signalled. Resetting must take place manually following
a fault lock-out.
12 .9 Safety interlocks (Limits)
The limiters in the safety interlock (linking of all the relevant
safety control and switching equipment for the use of the ap-
plication, for example STB (safety temperature limiter), Gas
min
,
Gas
max
...) must isolate input 3 from the voltage supply.
12 .10 Gas valve V1
The start fuel flow rate is released by gas valve V1. The gas
valve V1 opens at the start of the safety time on start-up t
SA
.
It remains open until the burner is switched off again by a
controlled shut-down or fault lock-out.
12 .11 Continuous operation
The gas burner has been running for longer than 24 hours
and was not switched off during that time.
