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3
Functional Description
3.3
Mode of operation
The compact flame detector converts the flame radiation pulsing of the burner flame into elec-
trical signals. These signals are routed to an electronic changeover switch, which alternately
applies them to one of the independently working processing channels, where the signals are
digitised. This reduces the initial signal quantity to the information ’pulse period’ (information
carrier: pulse frequency of the flame radiation).
The digitised signals are compared with the related reference signals by means of a digital
frequency evaluation unit. This ensures that only those flame signals that are within the pre-
selected frequency transmission range will be included in a continued processing, irrespective
of their original amplitude. A control switch (for the F200K2 only) located below the removable
cover allows the operator to change the lower frequency limit if required. After evaluation, the
flame signal is routed to the switching amplifier, which also controls the related shut-down
time.
A safe monitoring of the antivalent control states as well as the response and shut-down pe-
riods is performed at the output of the signal processing channels, before an activation of the
output relays at the end of each signal processing channel is carried out. Antivalence faults
and deviation in time delays going beyond the admissible limit values result in the control state
’Flame out’.
The control states ’Flame out’ and ’Flame in’ are indicated on the rear side of the device by
means of a red and/or green LED. The change-over between the two signal processing chan-
nels is indicated by pulsing of the green LED during the ’Flame in’ control state.
Additionally one or two six-step control switches provide for a sensitivity adjustment to adapt
the system to the flames to be monitored, this being indicated by means of a six-step chain of
green LEDs designed to be the device's flame intensity indicator.
Miscellaneous
Self-monitoring principle
Signal processing is carried out by means of two transmission channels working independent-
ly of each other and alternately triggered. The output levels are permanently checked for an-
tivalence within a given time grid.
Parameter adjustment, combustion system type
monitoring equipment
Using the control rotary switch on the F200K/F200K2 compact flame detectors enables be-
tween 6 and 12 sensitivity levels to be set. The F200K2 version allows an increased sensitivity
in range II to be set. A six-step green LED indicator indicates the evaluated flame intensity on
the rear side of the device. The transmission range of the digital flame frequency evaluation
allows for signal passage between10 ... 190 Hz (F200K1) and/or 10 / 20 / 30 ... 190 Hz
(F200K2).
