BFI Automation 3016, Original Operating Instructions

Page: 36 / 56

Description
5-2
A self-test rate is generated. The pulses (or digits) sup-
plied by the flame scanner are conditioned at first, to
eliminate cable loss and interference. Subsequent to this,
the signal path is split into two.
An analogue monitoring channel ensures a safe switch-off
in case of a failure of the parallel operating processor cir-
cuit. The flame relay is activated only if both, monitoring
channels as well as the processor circuit, have recog-
nised the flame-on signal.
5.4 Sensetivity adjustment
The unit can be sensitivity adjusted with the possibility to
pre-select one of the two channels externally. The proc-
ess control must furnish a predetermined signal for this
purpose. The selected channel is displayed on the two
green LED’s at the front plate.
At the same time the process control can receive a re-
information.
It has to be taken into consideration that the time between
channel selection and actual switch-over can be up to 1s.
Sensitivity adjustment is achieved by means of a 16-digit
(hexadecimal) turn switch at the front plate. There is one
turn-switch for each channel (the active sensitivity level
has to be taken care of for the adjustment). The 0 position
requires a stronger signal to activate the flame relay. The
sensitivity can be increased beyond step 9 (A, B, C, D, E,
F) up to switch position F. In this position a very weak
signal is sufficient already to activate the flame relay. The
sensitivity has to be chosen as such that during normal
operation all bar graphs of the intensity indication are il-
luminated, whereas a flickering on the first bar must be
recognisable. If the sensitivity is adjusted too high delays
in switch-off could be the result and should therefore be
avoided. A value between 4 and 6 is generally sufficient.
During the sensitivity adjustment it has to be borne in
mind, that the switches are scanned only once per sec-
ond, and an instant change is therefore not always possi-
ble.