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Electrical connection of flame detectors
Commissioning notes
4/24
Building Technologies Division
Infrastructure & Cities Sector
It is important to achieve practically disturbance- and loss-free signal transmission:
Never run the detector cable together with other cables
– Line capacitance reduces the magnitude of the flame signal
– Use a separate cable
Observe the permissible detector cable lengths (see Technical data)
It is not permitted to connect 2 flame detectors QRA53.../QRA55... in parallel
When using the QRA53.../QRA55..., earthing of terminal 22 is mandatory
The ionization probe is not protected against electric shock hazard
Locate the ignition electrode and ionization probe such that the ignition spark
cannot arc over to the ionization probe (risk of electrical overloads) and that it
cannot adversely affect the supervision of ionization
Supervision with ionization probe and QRA... flame detector is possible but, for
safety reasons, both must not be active at the same time, with the exception of the
second safety time (t9). At the end of the second safety time, one of the detected
flames must extinguish, e.g. by shutting down the pilot gas valve connected to
terminal 17
When commissioning the plant or when doing maintenance work, make the
following safety checks:
Safety check to be carried out
a)
Burner startup with flame detector
darkened
b)
Burner startup with simulated
flame
c)
Burner operation with simulated
loss of flame; for that purpose,
darken the flame detector in
operation and leave it in that state
d)
Burner startup with response of air
pressure switch
e)
Burner operation with simulated air
pressure failure
Anticipated response
Lockout at the end of safety time
Lockout after no more than 40 seconds
LOK16... with wire link cut: Start
repetition followed by lockout at the end
of safety time
LGK16... and LOK16... with wire link
closed: Immediate lockout
Prevention of startup/lockout during
prepurge time
Immediate lockout
CC1N7785en
06.03.2012
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