Siemens LMV5 Series Manual page 14

Technical data (cont'd)
Flame supervision
QRB... (for intermittent
operation only)
Indication of flame
AZL5...
14/39
Building Technologies Division
Industry Sector
No-load voltage at the QRB... terminal
(X10–02, terminal 1)
Detector current required (with flame)
Permissible detector current (dark current
with no flame)
Permissible detector current
Permissible length of QRB... detector ca-
ble (lay separately)
Note!
A detector resistance value of RF <5 kΩ is identified as a short-circuit and, in opera-
tion, will lead to safety shutdown as if loss of flame had occurred. Measurement of the
voltage at terminal QRB... during burner operation gives a clear indication: If voltage
drops below 1 V, safety shutdown will probably occur. For that reason, before using a
highly sensitive photoresistive flame detector (QRB1B, QRB3S), it should be checked
whether such a detector is really required! Increasing line capacitance between the
QRB... terminal and mains live «L» adversely affects the sensitivity and increases the
risk of damaged flame detectors due to mains overvoltages. Separate routing of detec-
tor cables as specified in Data Sheet 7714 must be observed.
Configuration
extraneous light
In the case of incinerator plant or other types of plant operating at combustion chamber
temperatures of >650 °C, an extraneous light test must not be made.
Caution!
Observe the relevant standards and regulations (e.g. extra supervision of the
combustion chamber temperature)!
Caution!
QRB... must not be used when extraneous light suppression is activated since
detector tests will not be made in that case!
For indication of flame (on the AZL5...), observe the following general rules:
The above percentage values are obtained when, for parameter «Standardize» (stan-
dardization of flame signal), the default setting is used. The accuracy of the display is a
maximum of ±10 %, depending on the tolerances of the components. It should also be
noted that, for physical reasons, there is no linear relationship between the display and
the detector signal values. This is especially obvious with ionization current supervision.
For more detailed information, refer to Data Sheet N7714.
Approx. DC 8 V
Min. DC 30 µA
Display flame 35 %
Max. DC 5 µA
Max. DC 70 µA
Display flame approx. 100 %
100 m (wire-wire 100 pF/m)
CC1N7550en
24.05.2011