Passive infrared detectors are a type of detector that is most commonly used in security engineering. However, for its normal use, it is necessary to prevent omissions, but also to reduce false positives, mainly to minimize false positives. To achieve this, we must first understand some of the basic concepts and technical characteristics of passive infrared detectors, so that in accordance with these basic technical characteristics, from the installation, debugging, use and other aspects, in accordance with the basic technical characteristics of the detector, In order to maximize the detector's maximum efficiency.
First of all, we must understand the following information, which will be of great help to the correct use of passive infrared detectors.
1. Determine the mounting height according to the instructions
The installation height of the detector is not random, and it will directly affect the sensitivity of the detector and the effect of preventing animals. Generally, the installation height of the wall-mounted infrared detector is 2.0-2.2 meters.
2. Should not face glass doors and windows
There are two problems facing the glass doors and windows: First, white light interference, although the passive infrared detector (PIR) has a strong suppression of white light, but after all, is not 100% inhibition, do not face the glass doors and windows, you can avoid glare The second is to avoid complex environmental disturbances outside the doors and windows, such as direct sunlight, crowds, and mobile vehicles.
3. Should not be on the hot and cold vents or cold and heat sources
The induction effect of the passive infrared detector is closely related to the temperature change. Both the cold and hot vents and the cold and hot sources may cause false alarms for the detector. For some low-performance detectors, air convection through windows and doors sometimes occurs. Caused false positives.
4. Should not be facing large swingable objects
A large swing of a large object can momentarily cause sudden changes in the air flow in the detection area. It can also cause false alarms; for example, the outdoor detectors must avoid large trees and tall shrubs.
5. Reasonable position
There should be no screens, furniture, large bonsai or other partitions within the detection range; it is best not to install two wireless infrared detectors in the same space to avoid the phenomenon of interference caused by simultaneous triggering; infrared detectors should be The indoor walking line is at a certain angle. The detector is least sensitive to radial movements, and most sensitive to movement in the tangential direction (ie, perpendicular to the radius). Selecting the proper installation location on site is an extremely important step to avoid false alarms for infrared detectors and to obtain the best detection sensitivity.
6. Reasonable selection
Passive infrared detectors have a variety of models, from indoor to outdoor, from wired to wireless, from single infrared to three infrared, from wall-mounted to ceiling-mounted, so the detectors to be installed must consider the size of the prevention space , the surrounding environment, the characteristics of the entrance and exit and other actual conditions.
After installing the detector, the commissioning of the detector is the last thing to do. The commissioning of passive infrared detectors is usually step-by-step. That is, the commissioning personnel walks the S-type line in the alert zone to sense the length and width of the alert range to test whether the entire alarm system meets the requirements. The instructions can be consulted to properly adjust the detector's sensitivity. Excessively high or low sensitivity will affect the preventive effect.
First of all, we must understand the following information, which will be of great help to the correct use of passive infrared detectors.
1. Determine the mounting height according to the instructions
The installation height of the detector is not random, and it will directly affect the sensitivity of the detector and the effect of preventing animals. Generally, the installation height of the wall-mounted infrared detector is 2.0-2.2 meters.
2. Should not face glass doors and windows
There are two problems facing the glass doors and windows: First, white light interference, although the passive infrared detector (PIR) has a strong suppression of white light, but after all, is not 100% inhibition, do not face the glass doors and windows, you can avoid glare The second is to avoid complex environmental disturbances outside the doors and windows, such as direct sunlight, crowds, and mobile vehicles.
3. Should not be on the hot and cold vents or cold and heat sources
The induction effect of the passive infrared detector is closely related to the temperature change. Both the cold and hot vents and the cold and hot sources may cause false alarms for the detector. For some low-performance detectors, air convection through windows and doors sometimes occurs. Caused false positives.
4. Should not be facing large swingable objects
A large swing of a large object can momentarily cause sudden changes in the air flow in the detection area. It can also cause false alarms; for example, the outdoor detectors must avoid large trees and tall shrubs.
5. Reasonable position
There should be no screens, furniture, large bonsai or other partitions within the detection range; it is best not to install two wireless infrared detectors in the same space to avoid the phenomenon of interference caused by simultaneous triggering; infrared detectors should be The indoor walking line is at a certain angle. The detector is least sensitive to radial movements, and most sensitive to movement in the tangential direction (ie, perpendicular to the radius). Selecting the proper installation location on site is an extremely important step to avoid false alarms for infrared detectors and to obtain the best detection sensitivity.
6. Reasonable selection
Passive infrared detectors have a variety of models, from indoor to outdoor, from wired to wireless, from single infrared to three infrared, from wall-mounted to ceiling-mounted, so the detectors to be installed must consider the size of the prevention space , the surrounding environment, the characteristics of the entrance and exit and other actual conditions.
After installing the detector, the commissioning of the detector is the last thing to do. The commissioning of passive infrared detectors is usually step-by-step. That is, the commissioning personnel walks the S-type line in the alert zone to sense the length and width of the alert range to test whether the entire alarm system meets the requirements. The instructions can be consulted to properly adjust the detector's sensitivity. Excessively high or low sensitivity will affect the preventive effect.
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