Siemens LMV5 Series Manual page 13

Technical data (cont'd)
Flame supervision
QRB (for intermittent
operation only)

Flame signal display
AZL5
Building Technologies Division
No-load voltage at the QRB terminal
(X10–02, pin 1)
Detector current required (with flame)
Permissible detector current (dark current
with no flame)
Permissible detector current
Permissible length of QRB detector cable
(lay separately)
Note!
A detector resistance value of RF <5 k is identified as a short-circuit and, in
operation, 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 detector cables as specified in Data Sheet 7714 must be observed.
For more detailed information, refer to Data Sheet N7714.
Caution!
Flame detectors QRB must not be used when extraneous light suppression is
activated since detector tests are not made in that case (parameter
ExtranLightTest = deactivated)!
Caution!
Observe the relevant standards and regulations (e.g. extra supervision of the
combustion chamber temperature)!
The following applies in general to the flame signal display (AZL5 display and
operating unit):
The percentages values listed above result from the factory setting of the parameter
Standardize (standardization of flame signal display).
The display is subject to various component tolerances, with the result that deviations
of 10 % are perfectly possible.
It should furthermore be noted that for physical reasons, there is no linear connection
between the display and detector signal values.
This is especially apparent in supervision of ionization.
Approx. DC 8 V
Min. DC 30 µA
Display flame 35 %
(at factory setting of StandardFactor
parameter)
Max. DC 5 µA
Max. DC 70 µA
Display flame approx. 100 %
(at factory setting of StandardFactor
parameter)
100 m (wire-wire 100 pF/m)
)
)
13/29
CC1N7550en
22.05.2017