Operation - Bosch D296 Installation Instructions Manual

Long-range Beam Smoke Detectors
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2.2

Operation

Each transmitter sends an invisible infrared beam of a specific frequency and intensity. Each
receiver detects and measures the beam's intensity (see the following figure).
Figure 2.1: Infrared Transmission
As smoke obscures the beam, the receiver senses a decrease in the signal strength and
measures that decrease. The receiver compares the signal level with two preset thresholds: an
alarm threshold that is set using the sensitivity switch and a trouble threshold that is preset at
approximately 10%. If the signal falls below the alarm threshold for the programmed alarm
period, the receiver signals an alarm (see the following figure).
Figure 2.2: Beam Obscuration
If the signal falls below the trouble threshold for more than 20 sec (caused by an object
blocking the beam for example), the receiver signals a trouble condition (see the following
figure).
Bosch Security Systems, Inc.
A D306 Remote Indicator Plate, a D1005 Test Cable, and a set of four plastic sensitivity
test filters are included with each detector.
A D307 Remote Test and Indicator Plate (not supplied) is required for remote alarm
testing.
A D308 Test Kit (not supplied) is needed for field testing.
A D309 Alignment Light is also available to aid in transmitter/receiver alignment.
1 Transmitter
2 Beam
1 Transmitter
2 Beam
Installation Instructions
3 Receiver
3 Obscuring matter
4 Receiver
2014.01 | 06 | F.01U.068.899
Notices | en 5