Cause Analysis and Solution of False Alarm of Passive Infrared Detector

First, the principle of passive infrared detector
In nature, any object above the absolute temperature (-273 degrees) will produce an infrared spectrum. In the passive infrared warning zone, when no object moves, the pyroelectric infrared sensor senses only the background temperature when moving the object. Entering the warning zone, through the Fresnel lens, the pyroelectric infrared sensor senses the difference between the temperature of the moving object and the background temperature, and the alarm signal sent after the infrared signal change is converted into an electrical signal. The passive infrared detector itself does not emit in the infrared spectrum.
 
Second, the false alarm caused by equipment failure
1. Damaged faults. Including all failures and sudden failures of performance. Such failures are usually caused by damage to components or poor manufacturing processes (such as solder joints, false soldering, etc.).
2. Drift failure. It refers to the fault caused by the parameter of the component and the excessive drift of the power supply voltage. For example, if the temperature is too high, it will cause a change in the resistance value. At this time, the device behaves as good or bad.
Third, false alarms caused by environmental changes

1. The equipment is not installed securely and often moves to cause false alarms;
2. A false alarm is caused by the temperature change of the air conditioner and the ventilation fan;
3. Prevent the area door or window from being closed, and some people or animals may cause false alarms;
4. When the temperature difference between indoor and outdoor is large, the wind blows the curtain to cause false alarm;
5, multiple detectors simultaneously transmit signals, which can cause false negatives or interference (only wireless type);
6. The alarm system causes false alarms to other wireless infrared detectors. The device behaves as good or bad (only wireless).
Fourth, the solution
1. Install an infrared detector according to the installation requirements of the manual;
2. Avoid areas with strong temperature difference and air convection;
3. The doors and windows in the prevention area are closed, and the detector is normally turned on;
4. Close the doors and windows or bind the curtains;
5. Reduce the cross-detection range of the prevention area and avoid transmitting the alarm signal at the same time;
6, fast and accurate code, to prevent mis-recording information.
Five, the guarantee of low false positives
1. “0” misreported misleading products. To believe that PIR is a product of detecting sensors, there is no absolute “0” false positive product, and continuous optimization of technology can be used to reduce the frequency and frequency of false positives. The reason is that the infrared detector is only determined by the program set in the detector microprocessor in a specific environment and specific conditions. Sensitivity of detection is subject to changes in environment and conditions, and changes in the control environment are key to reducing false alarms.
2. CCC certification. CCC compulsory certification of qualified products is a must, and high-quality electronic components, strict quality system maintenance, credible quality commitment and perfect after-sales service are also selected.
3, multi-technology combination discrimination to improve the reliability of the detector, the current products are: passive infrared detector, microwave + passive infrared double detector, voice + vibration glass broken double detector, ultrasonic + passive infrared double detector Wait.
4. Special circumstances. Some environmental noise double detectors can't do anything, for example: mice in the guard zone; pets walking around the room. To this end, the scientific and technical personnel have introduced the micro-processing technology into the alarm system, so that it has certain identification and logical discriminating ability, and can judge to some extent whether it is an intruder or an environmental noise-caused alarm.

Boiler Auxiliary Equipment

Soot Blower 001 JpgBoiler auxiliary equipment mainly includes water supply equipment, ventilation equipment, fuel supply, slag removal and dust removal equipment, steam and water pipes and accessories, detection instruments and automatic control equipment.



1. Water supply equipment


It is composed of water treatment equipment, water supply tank and feed pump 24. Water treatment equipment is used to remove impurities in water, such as oxygen, calcium and magnesium ions, to avoid scaling and corrosion on the inner wall of steam boiler, and to ensure the quality of boiler water supply. The treated boiler feed water is lifted by the feed water pump and then sent to the upper drum through the economizer.




2. Ventilation


The ventilation equipment includes air supply fan, induced draft fan and chimney. Its function is to provide air for mule fuel combustion and lead out combustion product flue gas from the boiler, so as to ensure the normal combustion, and make the flue gas wash the heating surface at the necessary flow rate of 7a68696466fe78988e69d8331333433626465 to strengthen heat transfer. Finally, the stack with a certain height will exhaust the smoke to the atmosphere to reduce the smoke pollution and improve environmental health.



3. Fuel supply, slag removal and dust removal equipment

This is for conveying fuel to boiler, removing ash and purifying flue gas. Belt conveyor, ash conveyor, ash truck and dust remover, etc. For boilers that need to be pre processed with fuel, fuel preparation such as screening, crushing and coal grinding shall also be included. In addition, the dust remover or flue gas desulfurization and denitrification device installed in the flue at the tail of the boiler is an indispensable auxiliary equipment to reduce the smoke pollution and protect the environment.




4. Check instruments and automatic control equipment


In addition to water level gauge, pressure gauge, safety valve and other instruments installed on the boiler body, in order to supervise, regulate and control the safe and economic normal operation of the boiler equipment, a series of instruments, automatic boiler feed water regulating device, automatic fuel combustion control device, etc. are often installed. Some boiler rooms are also equipped with industrial television and remote control device and even more modern automatic control system, more Scientific supervision. Control boiler operation.


Boiler auxiliary equipment, not every boiler is equipped completely, but with the boiler capacity, type, fuel characteristics and combustion mode as well as water quality characteristics and many other factors to adapt to local conditions, adapt to the times, more practical requirements and objective conditions.



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