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Building Technologies Division
Basic Documentation LME7...
CC1P7105en
Infrastructure & Cities Sector
4 Technical data
29.11.2011
4.10.2 Flame detector QRA2.../QRA4.U/QRA10...
Caution!
If flame detectors QRA2…/QRA4.U/QRA10... are used for flame supervision with
the LME7..., it must be ensured that the burner control is permanently
connected to power (conforming to EN 298), thus enabling the system to detect
flame detector failures during startup and shutdown.
Generally, the system works with QRA... flame detectors in intermittent
operation. If this is not observed, there is a risk of loss of safety functions.
Technical Data see
Data Sheet N7712, flame detector QRA2.../QRA10…!
Technical Data
see Data Sheet N7711, flame detector QRA4.U!
Threshold values when flame is supervised by QRA...
- Start prevention (extraneous light)
- Start prevention (extraneous light)
- Operation
- Operation
Operating voltage
AC 280 V ±15%
Mains frequency
50...60 Hz
6%
Required detector current
Min. 70 µA
Possible detector current
- Operation
Max. 700 µA
Perm. length of detector cable
- Normal cable, laid separately ¹)
Max. 100 m
¹)
Multicore cable not permitted
Flame detector QRA...
QRA...
Figure 5: Measuring circuit for QRA...
Legend
A
Exposure to light
C
Electrolytic condenser 100...470 µF; DC 10...25 V
M
Microammeter Ri max. 5,000
Warning!
Input QRA... is not short-circuit-proof!
Short-circuits of X10-06/2 against earth can destroy the QRA... input
Simultaneous operation of flame detector QRA... and ionization probe is not
permitted. If not observed, there is a risk of impairment of safety functions.
To make certain the age of the UV tube can be determined, the LME7...
basic unit must always be connected to mains supply. If not observed,
there is a risk of impairment of safety functions.
Measuring circuit for detector
current measurement