34
Adjusting Instructions
Flame Monitor
Sensor Current Measurement
Flame monitor with photoresistor
A photoresistor is used as the light-sen-
sitive element of the QRB series. The
resistance of this element will decrease
with rising illumination intensity. In the
dark condition the element will develop
a high resistance, i.e. a resistance in the
M range, while under the influence of
light the element will develop a low resi-
stance, i.e. in the K range. The after-
glow of the furnace lining will be detec-
ted.
Flame monitor with photocell
A selenium cell is used as the light-sen-
sitive element of the RAR series. In illu-
minated condition this cell will generate
a DC voltage and thus cause a current
to flow to the input of the flame signal
amplifier. Thus, the selenium photocell
sensor is an active sensor. The cell is
insensitive in the infrared range so that
light glowing parts of the furnace refrac-
tory lining will not be detected.
Application
The LAL 2... automatic furnace control-
ler with its QRB1/3 flame sensor is
mounted to burners with intermittent
mode of operation which are shut down
within 24 hours.
Application
Burners operated in continuous or inter-
mittent mode for periods in excess of 24
hours (e.g. boiler sequential control) or
burners operated in steam boilers must
be equipped with the LOK 16... automa-
tic furnace controller with its RAR flame
sensor.
Cleaning the sensor
Check the sensor window for possible
accumulation of dirt at regular intervals
and clean if required.
Take care the sensor window is kept
free of dust at any time.
If upon cleaning the sensor does not
properly work it will be required to
replace it by a new one.
Sensor currents
The sensor current is measured to
check the intensity of the light radiation
at the place of installation of the sensor.
Automatic furnace controller
Photoresistor sensor QRB 1/3
QRB 1/3
LAL 2...
Automatic furnace controller
Photocell sensor RAR
LAL 2 / LOK 16
Recommended instrument range:
0 - 100
µ
A
* See technical data for automatic furnace controller LAL 2 / LOK 16
Automatic controller
Minimum
required
Maximum
possible
Monitor
with sensor
with sensor
* LAL 2.25 (QRB 1/3)
8
µ
A
35
µ
A
* LAL 2.25 (QRC 1)
3,9
µ
A
0,8
µ
A (without flame)
* LOK 16 (RAR...)
6,5
µ
A
25
µ
A