Cable burglar alarm should catch "four defenses"

In recent years, the theft of cables has been very serious. Whether it is the city street lamp cable or the overhead aerial cable of the mining area, theft has occurred in an endless stream. This has seriously affected the effectiveness of urban public facilities and directly or indirectly caused personal safety damage. In order to effectively carry out anti-theft work on cables, many cities have even started to set up daily inspection systems for the lines. On the one hand, they started the cable alarm system, and on the other hand, they also strengthened the prevention and control of frequent-fire areas.

The cable anti-theft alarm is designed to compare the fixed value with the impedance value of the street light cable. When someone cuts a section of cable, the cable impedance value will change. When the change value is larger than the artificially set fixed value, the instrument will send an alarm signal. The "four defenses" in cable theft, namely "human defense, soil defense, technical defense, and joint defense", effectively mitigated the theft of cables.

The common cable anti-theft technology 1, power carrier communication monitoring system anti-theft power carrier belongs to a concept derived from the cross-discipline of power and communications. The power carrier communication method utilizes signal transmission means in the wire and cable anti-theft system to load the detection carrier signal on the cable in the detection range. The alarm center of the monitoring center is connected to the carrier signal on the monitored cable. Once the cable outlet cross section causes signal transmission interruption If the alarm can't receive the signal, it will automatically alarm and play an alert role. The power carrier communication method is currently the most widely used anti-theft measure because it transmits carrier signals on the monitored cable and does not require extra lines. Therefore, the power carrier communication method is easy to install, conceals detection, and has a wide monitoring range. A few kilometers or more) and so on. However, since the cable can only be stolen when the cable is stolen, it cannot be deterred to criminals, and video video forensics is not available. The single power carrier communication is facing challenges of integration and systematization.

2. Capacitance detection and monitoring system The principle of the anti-theft capacitance detection method is to first use a pair of empty cables to short the cable terminals and the other end to connect the multivibrator of the alarm. When the cable works normally, the oscillator of the alarm device will not generate vibration; When the cable outlet cross-section, the empty cable becomes a simple capacitor, the oscillator will output a signal, causing an alarm, and the frequency of the oscillator output signal varies with the cable cut-off position.

3, current detection type monitoring system anti-theft system to determine the integrity of the cable system to determine whether there is a transmission current in the cable loop. In other words, when the cable works normally, the detection system will not respond; when there is no current transmission in the cable, the detection system will start the alarm system. The current detection system can not be used for voltage anti-theft systems with no current, such as subway tunnels or highway tunnel blower power cables. In addition, the system can only alarm when all branch cables of the circuit system are cut off (because the total current of the cable circuit is zero when the cable branch is completely disconnected). Therefore, the current detection type monitoring system has hidden dangers of “not reporting”.

The technical anti-theft requirement of the common stolen cable is as follows: 1. The anti-theft alarm of buried cables for street lamps is rapidly developed with the integration of urban and rural areas in the country, accelerating the pace of rapid development of municipal construction. The street lamp is the main part of the city's night landscape lighting, and plays an important role. The cable for the street lamp has now been converted from overhead installation to underground laying. The underground laying of street lamp cables mainly includes: direct laying, pipe laying, and cable trench laying. No matter which kind of laying, there are hidden dangers of being stolen, leading to serious consequences such as economic loss and disorderly public order.

The ideal road buried cable anti-theft system, the most important requirement is in the off period, the alarm anti-theft system requires the end of the power without any form; turn on the light when the alarm is working in the normal anti-theft system and circuit status (cable length, street lamp model Etc.) No direct relationship. When possible, multiple lines are used to communicate with the control room through a communication device through a master device.

2. Expressway power cable anti-theft alarm The highway mainly uses power cables, and one of the core issues in the development of highway cable anti-theft alarm systems is signal detection when cables are abnormal. For highway cable requirements, the main requirements of the anti-theft system are: availability, reliability (low false alarm rate), advanced (alarm discrimination), scalability (and high-speed traffic police system networking) and so on.

Conclusion In recent years, China's economy has grown rapidly, and the process of industrialization and urbanization has further accelerated. As a result, the wire and cable industry in China has been rapidly developing, and its output value has become the second largest industry in the electrical and electronic industry, second only to the automobile manufacturing industry. According to the results of the joint quality inspection of wire and cable products conducted by the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) in 2012, the average pass rate of wire and cable products in the production field reached 88.2%. In the situation where the wire and cable are continuously improving safety and quality, the security and anti-theft system must not be ignored!