Spectrex 20/20U (UB) - UV Flame Detector - Manual (Page 11)

Spectrex Inc. - SharpEye™ UV Flame Detector Manual – TM 20/20UB Rev. E, August 2004
3
2.4 Alarm Signal Delay
The detector is adapted with an Alarm Signal delay selector, providing a user to
set a different delay between 0 to 30 seconds, mandatory for several specific
applications.
When Alarm level detection conditions are met, an internal time delay is initiated
as preset on the selector. Once the preset time delay has elapsed, detection
conditions are evaluated for 3 seconds. If during that evaluation period Alarm
level detection conditions persist, the Alarm signal is triggered. If no Alarm level
detection conditions endure, the Alarm signal Delay is reset.
2.5 Built-In-Test (BIT) Capabilities
The detector is adapted with BIT (Built-In-Test only in 20/20UB) capabilities. The
automatic BIT is performed at predetermined time intervals averaging 60
minutes. It performs automatic full-featured test of the detector’s internal
electrical circuits, checks the radiation sensors and the detector window’s
cleanliness.
The BIT circuits will generate response signals to indicate adequate operation of
the detector or a fault should it be detected during a BIT sequence.
The BIT sequence can also be initiated manually by the user at his preference,
upon a remote operation from a control unit.
The Auto BIT does not check the output stages and the connection to the control
system. Should you wish to check the output stages and wiring to the controller,
a manual BIT should be performed - refer to section 7.4.
2.6 Detector Structure
Figure 1 presents an outline drawing of the Flame Detector Assembly. Figure 2
presents a schematic section of the internal Flame Detector, and describes its
main components.
2.7 System Configuration
The Spectrex model 20/20U, 20/20UB is a self-contained Optical Flame Detector
that can function as a stand alone unit directly connected to external devices as
alarm systems or automatic fire extinguishing systems. The same detector can
form part of a more complex system where a plurality of detectors and other
devices are integrated through a dedicated control unit.