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Building Technologies Basic Documentation LME7... CC1P7105enr
4 Technical data 17.04.2018
4.12.2 Flame detector QRA2 / QRA4 / QRA10
Caution!
If flame detectors QRA2 / QRA4 / 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!
Threshold values when flame is supervised by QRA
- Start prevention (extraneous light) Intensity (parameter 954) approx. 12%
- Operation Intensity (parameter 954) approx. 13%
Operating voltage AC 280 V ±15%
Mains frequency 50...60 Hz °6%
Required detector current Min. 70 µA
Possible detector current during operation
Max. 700 µA
Perm. length of detector cable
(normal cable, laid separately) ¹)
Max. 100 m, unshielded
¹) Multicore cable not permitted
Flame detector 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 ς
Warning!
∂ Input QRA is not short-circuit-proof!
Short-circuits of terminal X10-06 pin 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 ensure that the age of the UV tubes can be determined, the LME basic
unit must always be connected to mains supply. If this is not observed, the
safety functions may be impaired.
Measuring circuit for detector
current measurement
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