OHD64 3
23
.
08
.202
1
2 Basic Technical Data
2.1 The detector sensitivity − 0.12 dB/m.
2.2 The detector ensures the generation of the «Actuation» signal upon reaching the response
temperature 58 °C.
2.3 The detector interference protection is adjustable in the range from 1 to 10 s.
2.4 The operating range of supply voltage of OHD64 from the ACL is (24 – 36) V. The current
consumption of OHD64 from the ACL in the indicated voltage range is 0.28 mA, max.
2.5 Overall dimensions of the detector without a base – 94 × 44 mm, max.
Overall dimensions of the detector with bases:
– W1.02, W1.03 – 94 × 46.5 mm, max;
– W2.02, W2.03 – Ø142 (on the flange) × 66 mm, max.
2.6 Detector weight without a base – 80 g, max.
Detector weight with bases:
– W1.02, W1.03 – 120 g, max;
– W2.02, W2.03 – 160 g, max.
2.7 Protection rating provided by the detector enclosure according to IEC 60529 − IP40.
2.8 Average service life - 10 years.
2.9 Mean time between failures - at least 60,000 hours.
2.10 Probability of no-failure operation for 1,000 hours - at least 0.98.
3 Detector Design and Principle of Operation
3.1 The detector is a combination of the electro-optical device and the direct temperature measurement
device. Information is processed by the built-in microcontroller. The microcontroller and other electronic
components are located on the printed circuit board and placed within the plastic enclosure.
3.2 The detector is installed in the base (types of bases − see 1.9). The detachable connection of the
detector to the base ensures easy installation, assembly and maintenance of the detector.
The
appearance of the detector is shown in Figure 1. The appearance of bases is shown in Figures 2 and 3.
3.3 The operating principle of the detector's optical channel is based on tracing the optical
(infrared)
radiation reflected from smoke particles. In the absence of smoke in the sensitive area of the optical system,
the detector is in standby mode. When smoke appears in the sensitive area of the optical system, the detector
processor generates an «Actuation» signal.
To reduce the probability of false alarms due to the dust accumulation in the smoke chamber, the detector
uses an algorithm of automatic compensation of sensitivity in case of the dustiness of the optical system. The
sensitivity is compensated before reaching the specified threshold at which the detector transmits the
information about this event to the fire alarm control panel, while the detector continues to perform all its
functions.
Upon reaching the “Preliminary dustiness threshold” it is necessary to provide the maintenance of the
detector (see Section 6). Upon reaching the “Critical dustiness threshold” the algorithm of automatic
compensation of sensitivity is switched off, the probability of false alarms increases, the maintenance of the
detector becomes vital. These events are shown in the event log and in the device status window
.
After cleaning the optical system, the detector automatically restores its serviceability in the full scope.
3.4 The temperature is measured by the microcontroller by the change in resistance of the temperature-
sensitive element. The rate of temperature change is calculated by the microcontroller.
3.5 If the smoke concentration in the room, the temperature or the rate of temperature change exceeds the
values set during configuration, the «Actuation» signal is generated. The signal may be reset from the
Device.