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Building Technologies Basic documentation LMV37.4... CC1P7546en
HVAC Products 4 Technical Data 01.12.2009
4.4.3 Photoresistive detectors QRB…
No-load voltage at QRB... terminal
(X10–05 terminal 3)
Approx. DC 5 V
Max. perm. length of QRB... detector
cable (laid separately)
3 m (wire – wire 100 pF/m)
&
Note
A detector resistance of RF <500 Ω is identified as a short-circuit and leads to safety
shutdown in operation as if the flame had been lost.
For this reason, before considering the use of a highly sensitive photoresistive detector
(QRB1B... or QRB3S), it should be checked whether this type of flame detector is really
required! Increased line capacitance between QRB... connection and mains live wire L
has an adverse effect on sensitivity and increases the risk of damaged flame detectors
due to overvoltage. Always run detector cables separately!
Threshold value flame supervision QRB… with LMV37.4...
Start prevention (extraneous light)
with R
QRB
<400 kΩ
Intensity >10%
Operation with RQRB <230 kΩ
Intensity >16%
Short-circuit detection with RQRB <0.5 kΩ
QRB... input
Detector resistor in kOhm
Flame intensity in %
100
90
80
70
60
50
40
30
20
10
0
0,1 1 10 100 1000
7540d04e/0508
Figure 3: QRB… input at AC 120 V / AC 230 V
4.4.4 Blue-flame detectors QRC…
Check the flame intensity via AZL2...
For system specific reasons, the display by AZL2... of maximum intensity is limited to
approx. 55 %.
Caution!
QRC… flame detectors are only suited for operation at AC 230 V.
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