Detector Current Measurement; Flame Supervision With Ionization Probe; Flame Supervision With Flame Detector; Measuring Circuit For Detector Current Measurement - Siemens LFL1.133 Manual

Technical data (cont'd)
Flame supervision with
ionization probe
Flame supervision with
flame detector QRA2 /
QRA4 / QRA10

Detector current measurement

Measuring circuit for
detector current
measurement
Legend
Building Technologies Division
Voltage at the ionization probe
- Operation
- Test
Short-circuit current
Recommended range of measuring
instrument
Perm. length of detector cable
- Normal cable, laid separately ²)
- Shielded cable
Required detector current in operation
Possible detector current in operation
Supply voltage
- Operation
- Test
Required detector current
Possible detector current
- Operation
- Test
Perm. length of detector cable
- Normal cable, laid separately ²)
- Shielded cable
¹)
During the prepurge time with higher test voltage: Self-ignition and extraneous light test
²)
Multicore cable not permitted
Ionization probe
M
+ -
+
LFL1... 24
C
7451v01/0204
For detector currents, refer to «Technical data».
C Electrolytic condenser 100...470 µF; DC 10...25 V
ION Ionization probe
Microammeter Ri max. 5,000 
M
AC 330 V ±10 %
AC 380 V ±10 %
max. 0.5 mA
0...50 µA
max. 80 m
max. 140 m (e.g. high-frequency cable;
shielding connected to terminal 22)
min. 6 µA
max. 200 µA
AC 330 V ±10 %
AC 380 V ±10 %
min. 70 µA
max. 700 µA
max. 1000 µA ¹)
max. 100 m
max. 200 m (e.g. high-frequency cable;
shielding connected to terminal 22)
Flame detector QRA2 / QRA4 / QRA10
M
-
A
ION
-
+
QRA...
LFL1...
23 22
+
C
7451v02/0204
11/25
CC1N7451en
20.11.2017