This article is for everyone to introduce the burglar alarm system false alarm analysis and troubleshooting, first introduced the definition of the next false alarm.
Regarding false alarms, there is currently no authoritative definition. In our country, it is generally accepted that “no alarm is issued when the alarm system is in danger.†According to this definition, the false alarm rate of the alarm system (in a certain period of time, the system The ratio of false alarms to the total number of alarms is generally above 95%. The definition of false alarms in some Western countries is: “False alarms are actual alarms that do not require* and cause the dispatch of alarm signals, which do not include those due to adverse natural climate and other special environments that cannot be manipulated by alarm companies and users. The alarm signal.†According to this definition, the US UL standard states: “Each alarm system can only have four false alarms per year.â€
The false alarm caused by the failure of the alarm equipment can't complete the specified function under the specified conditions and within the stipulated time, which is called fault. The types of failures are damaging and drifting.
Damaged failures include all failures of performance and abrupt failures. Such failures are usually caused by the damage of components or poor production processes (such as welding).
Drift fault refers to the fault caused by the drift of the parameters of the components and the supply voltage. For example, too high a temperature will cause a change in the resistance value of the resistor. At this time, the device will perform better or worse. In fact, factors such as ambient temperature, component manufacturing process, equipment manufacturing process, usage time, storage time, and power supply load may cause changes in the component parameters and cause drift faults.
Whether it is a damaging fault or a drift fault, it will make the system false alarms. To reduce the false alarms that result from this, efforts should be made from the following aspects.
(1) The production enterprise of alarm equipment must improve the design level and technological level of the product. At the same time as the system design, it must also be designed for reliability, such as redundant design, electromagnetic compatibility design, and three-proof design (moisture protection, salt protection) Fog, antifungal, drift reliability design, etc. On this basis, improve the reliability of product manufacturing processes, such as the strict screening of component quality; strict quality supervision and management of the production process, to ensure that product quality meets the requirements of the relevant standards.
Units or individuals that sell alarm equipment shall carry out strict incoming inspections. The contents of the inspection shall be: certification of product quality inspection; production license of industrial production enterprise or safety certification certificate or production registration approval letter.
(2) The management department shall regularly or irregularly organize inspections and random inspections of the security market, and discover that illegal activities in the production and sale of security product activities shall be handled in strict accordance with the provisions of the “Administrative Measures for the Prevention of Security Technology Productsâ€.
(3) The alarm system construction unit (user) shall clearly require the construction unit to use the products that have been inspected by the authorized testing agencies in the corresponding project documents; the foreign equipment shall use products that have been imported from the regular channels and inspected according to international advanced standards.
(4) In order to ensure the good working condition of the alarm system, a regular inspection and maintenance system must be established. By the way, at present, the maintenance methods of China's alarm system need to be resolved, and it is best to repair the variable-construction unit as the maintenance of a professional maintenance company. This will not only be beneficial to the use of maintenance resources (maintenance personnel, maintenance equipment, maintenance spare parts, etc.) The improvement of the maintenance level, more importantly, can improve the reliability of the security system.
The choice of false alarm caused by improper system design is the key to the system design. There are a wide variety of alarm devices and each has its own characteristics, application scope and limitations. Improper selection can cause false alarms. For example, the use of seismic detectors close to the source (airfield, railroad) can easily cause false alarms; the use of ultrasonic detectors in places where bats are frequent causes false alarms. This is because bats emit ultrasonic waves; High-frequency sounds, such as ring tones and metal impact sounds, can cause false alarms for single-technology glass break detectors. Therefore, to reduce false alarms caused by improper equipment selection, system designers must be familiar with the principles, characteristics, and scope of application of various alarm devices. And limitations. At the same time, we must also grasp the on-site environmental conditions, climate conditions, electromagnetic field strength, and changes in illuminance in order to select alarm equipment according to local conditions.
In addition to the selection of equipment and equipment, the improper design of the system also manifests itself in the equipment installation location, installation angle, protective measures, and system wiring. For example, laser intruder detectors are not fixedly installed. Strong winds or other vibrations may cause the laser to deflect the receiving end, which will cause false alarms for the system. If the active infrared detectors for outdoor use do not provide proper sun protection (with sun shields) The best is also for protection), it will inevitably cause the system to false alarm; when the distance between the alarm circuit and power lines, lighting lines and other strong electric circuit is less than 1.5m, without the protection against electromagnetic interference, the system will also generate false alarms.
This part of the problem of false alarms caused by improper construction is mainly manifested in the following aspects:
(1) No strict construction according to design requirements.
(2) Improperly installed equipment or improper inclination.
(3) Solder joints have vacant welds, burrs, or shielding measures.
(4) The sensitivity of the device is poorly adjusted.
(5) Inspection equipment for construction does not meet the measurement requirements.
The solution to the above problems is to strengthen the supervision and management of the construction process and implement the safety supervision system as soon as possible. This will help improve the quality of the project and reduce the number of false alarms due to construction.
The false alarm caused by the environmental nuisance The false alarm caused by the environmental nuisance refers to that the alarm system is generated under the normal working condition. It is unavoidable from the principle, but the fact is not necessary and it belongs to false alarm. For example, thermal airflow causes false alarms from passive infrared intrusion detectors; high-frequency sounds cause false alarms from single-technology glass break detectors; and ultrasonic sources cause false alarms from ultrasonic detectors. The most effective measure to reduce such false alarms is to use dual detectors (two different detectors detect the “target†at the same time, and the alarm only sends an alarm signal). The current products include: microwave-passive infrared double detector, voice-activated glass broken double detector, ultrasonic-passive infrared double detector and so on. However, some environmental noise detectors can't do anything, such as: rats infestation areas; pets walking in the room and so on. For this reason, scientists and technicians introduced laser technology into the alarm system. The laser adopts a certain frequency of wavelengths to avoid any unnecessary light interference from the surroundings. At the same time, multiple light alarms can be blocked to avoid false alarms caused by small animals crossing the defense zone.
Regarding false alarms, there is currently no authoritative definition. In our country, it is generally accepted that “no alarm is issued when the alarm system is in danger.†According to this definition, the false alarm rate of the alarm system (in a certain period of time, the system The ratio of false alarms to the total number of alarms is generally above 95%. The definition of false alarms in some Western countries is: “False alarms are actual alarms that do not require* and cause the dispatch of alarm signals, which do not include those due to adverse natural climate and other special environments that cannot be manipulated by alarm companies and users. The alarm signal.†According to this definition, the US UL standard states: “Each alarm system can only have four false alarms per year.â€
The false alarm caused by the failure of the alarm equipment can't complete the specified function under the specified conditions and within the stipulated time, which is called fault. The types of failures are damaging and drifting.
Damaged failures include all failures of performance and abrupt failures. Such failures are usually caused by the damage of components or poor production processes (such as welding).
Drift fault refers to the fault caused by the drift of the parameters of the components and the supply voltage. For example, too high a temperature will cause a change in the resistance value of the resistor. At this time, the device will perform better or worse. In fact, factors such as ambient temperature, component manufacturing process, equipment manufacturing process, usage time, storage time, and power supply load may cause changes in the component parameters and cause drift faults.
Whether it is a damaging fault or a drift fault, it will make the system false alarms. To reduce the false alarms that result from this, efforts should be made from the following aspects.
(1) The production enterprise of alarm equipment must improve the design level and technological level of the product. At the same time as the system design, it must also be designed for reliability, such as redundant design, electromagnetic compatibility design, and three-proof design (moisture protection, salt protection) Fog, antifungal, drift reliability design, etc. On this basis, improve the reliability of product manufacturing processes, such as the strict screening of component quality; strict quality supervision and management of the production process, to ensure that product quality meets the requirements of the relevant standards.
Units or individuals that sell alarm equipment shall carry out strict incoming inspections. The contents of the inspection shall be: certification of product quality inspection; production license of industrial production enterprise or safety certification certificate or production registration approval letter.
(2) The management department shall regularly or irregularly organize inspections and random inspections of the security market, and discover that illegal activities in the production and sale of security product activities shall be handled in strict accordance with the provisions of the “Administrative Measures for the Prevention of Security Technology Productsâ€.
(3) The alarm system construction unit (user) shall clearly require the construction unit to use the products that have been inspected by the authorized testing agencies in the corresponding project documents; the foreign equipment shall use products that have been imported from the regular channels and inspected according to international advanced standards.
(4) In order to ensure the good working condition of the alarm system, a regular inspection and maintenance system must be established. By the way, at present, the maintenance methods of China's alarm system need to be resolved, and it is best to repair the variable-construction unit as the maintenance of a professional maintenance company. This will not only be beneficial to the use of maintenance resources (maintenance personnel, maintenance equipment, maintenance spare parts, etc.) The improvement of the maintenance level, more importantly, can improve the reliability of the security system.
The choice of false alarm caused by improper system design is the key to the system design. There are a wide variety of alarm devices and each has its own characteristics, application scope and limitations. Improper selection can cause false alarms. For example, the use of seismic detectors close to the source (airfield, railroad) can easily cause false alarms; the use of ultrasonic detectors in places where bats are frequent causes false alarms. This is because bats emit ultrasonic waves; High-frequency sounds, such as ring tones and metal impact sounds, can cause false alarms for single-technology glass break detectors. Therefore, to reduce false alarms caused by improper equipment selection, system designers must be familiar with the principles, characteristics, and scope of application of various alarm devices. And limitations. At the same time, we must also grasp the on-site environmental conditions, climate conditions, electromagnetic field strength, and changes in illuminance in order to select alarm equipment according to local conditions.
In addition to the selection of equipment and equipment, the improper design of the system also manifests itself in the equipment installation location, installation angle, protective measures, and system wiring. For example, laser intruder detectors are not fixedly installed. Strong winds or other vibrations may cause the laser to deflect the receiving end, which will cause false alarms for the system. If the active infrared detectors for outdoor use do not provide proper sun protection (with sun shields) The best is also for protection), it will inevitably cause the system to false alarm; when the distance between the alarm circuit and power lines, lighting lines and other strong electric circuit is less than 1.5m, without the protection against electromagnetic interference, the system will also generate false alarms.
This part of the problem of false alarms caused by improper construction is mainly manifested in the following aspects:
(1) No strict construction according to design requirements.
(2) Improperly installed equipment or improper inclination.
(3) Solder joints have vacant welds, burrs, or shielding measures.
(4) The sensitivity of the device is poorly adjusted.
(5) Inspection equipment for construction does not meet the measurement requirements.
The solution to the above problems is to strengthen the supervision and management of the construction process and implement the safety supervision system as soon as possible. This will help improve the quality of the project and reduce the number of false alarms due to construction.
The false alarm caused by the environmental nuisance The false alarm caused by the environmental nuisance refers to that the alarm system is generated under the normal working condition. It is unavoidable from the principle, but the fact is not necessary and it belongs to false alarm. For example, thermal airflow causes false alarms from passive infrared intrusion detectors; high-frequency sounds cause false alarms from single-technology glass break detectors; and ultrasonic sources cause false alarms from ultrasonic detectors. The most effective measure to reduce such false alarms is to use dual detectors (two different detectors detect the “target†at the same time, and the alarm only sends an alarm signal). The current products include: microwave-passive infrared double detector, voice-activated glass broken double detector, ultrasonic-passive infrared double detector and so on. However, some environmental noise detectors can't do anything, such as: rats infestation areas; pets walking in the room and so on. For this reason, scientists and technicians introduced laser technology into the alarm system. The laser adopts a certain frequency of wavelengths to avoid any unnecessary light interference from the surroundings. At the same time, multiple light alarms can be blocked to avoid false alarms caused by small animals crossing the defense zone.
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