Summary of design technology for explosion-proof cameras for coal mines

The coal mine is a limited space and is a limited space with high gas, high dust, high temperature, high humidity and high danger. Therefore, the design of explosion-proof cameras for coal mines is complicated, and the requirements for explosion-proof cameras themselves are severe.

Normative Citation Standards: All standards will be revised, and parties using this standard should explore the possibility of using the most standard versions of the following standards.

GB/T191-2008 packaging storage and transportation icon mark

GB/T 2423.1-2008 Environmental testing of electric and electronic products - Part 2: Test methods Test A: Low temperature

GB/T 2423.2-2008 Environmental testing of electrical and electronic products - Part 2: Test methods Test B: High temperature

GB/T2423.4-2008 Environmental testing of electrical and electronic products - Part 2: Test methods Test Db: alternating heat (12h + 12h cycle)

GB 2423.5-1995 Environmental testing of electric and electronic products - Part 2: Test methods Test Ea and guide: Impact

GB 2423.8-1995 Environmental testing of electric and electronic products - Part 2: Test method test Ed: Free fall

GB/T 2423.10-2008 Environmental testing for electric and electronic products - Part 2: Test methods Test Fc and guide: Vibration (sinusoidal)

Q/LFJD-02-2018 Langfang Jiede Electronic Technology Explosion-proof Camera Product Standard

GB3836.1-2010 Explosive atmosphere - Part 1: General requirements for equipment

GB3836.4-2010 Explosive atmospheres - Part 4: Equipment protected by intrinsically safe "i"

GB/T4208-2008 enclosure protection grade (IP code)

GB/T9969-2008 General instructions for the use of industrial products

AQ 1043-2007 Mine Product Safety Sign Logo

MT 209-90 General technical requirements for electrical and electronic products for communication, testing and control of coal mines

MT 210-90 Basic test method for electrical and electronic products for communication, testing and control of coal mines

MT 211-90 Quality inspection rules for electrical and electronic products for communication, testing and control of coal mines

MT/T 154.2-1996 Coal mine electrical equipment product model preparation method and management method

For the harsh environment of the underground, the explosion-proof camera must have good performance of explosion-proof, high temperature, dustproof, waterproof, anti-corrosion, anti-vibration, anti-strong magnetic field and lightning protection. Almost 95% of the coal mines are relatively humid, and the waterproof grade must reach IP67; the mining products must be able to operate at high temperatures and anti-corrosion requirements in order to adapt to the humid, high pH environment.

In order to adapt to the harsh environment in the underground, the coal mine also has a choice of solutions. Since there is no light in the tunnel in the coal mine and infrared spotlights cannot be used, the CCD sensor of the low illumination camera is usually used. Secondly, because the working hours of the team are long, the power supply needs to be considered; and in order to ensure the work, it is necessary to select a large capacity. The battery, but the large capacity will lead to an increase in the difficulty of explosion protection. Therefore, the choice of battery capacity is the bottleneck of explosion-proof camera design. How to choose the power supply with large capacity, no leakage, adapt to high and low temperature and hot and humid environment, double protection redundancy, fast overcurrent cut-off switch function is a very difficult problem at present. According to the situation of various models in the industry, the small capacity battery is 750mA, most of the models are 1.5AH-2.0AH, and the current designed zui high capacity reaches 4AH.

Please refer to the Appendix

The coal mine security system is a large and complex system, including: digital explosion-proof video surveillance system, alarm system, integrated security management system. These security systems are centered on the digital explosion-proof video surveillance system, which is the main facility of the explosion-proof camera and the protagonist of the entire monitoring system. The coal mine is a highly flammable and explosive place, and ordinary monitoring will cause sparks to cause an explosion. Therefore, normal monitoring can be achieved after the explosion-proof work is done.

Explosion-proof monitoring with access control system and anti-theft alarm system as the core, through network interconnection, effectively integrate all technical resources and means to form a set of automated, intelligent, comprehensive prevention capabilities, and meet the characteristics of coal mines. The system meets the requirements of all levels of the entire security system of the coal mine.

Early explosion-proof cameras were dominated by positive pressure. The intrinsically safe explosion-proof camera is characterized by intrinsically safe handling of the circuit of the camera. The electrical line output or input is designed to be controlled below the energy that causes the hydrogen to ignite and explode, so that it does not generate electricity during normal operation. Sparks, arcs and high temperatures to avoid detonating explosive materials. The unit cost of this type of explosion-proof camera structure is the biggest disadvantage, and it is not conducive to future upgrades. The positive pressure type is a common structure of the early American explosion-proof camera products. It is quite inconvenient to maintain in use. If it is not carefully maintained, the risk of detonation is quite large. At present, this structure has been basically eliminated by the explosion-proof camera industry, except for a handful of Taiwanese manufacturers who are still manufacturing.

Although there are many explosion-proof types of explosion-proof electrical appliances, they are not all suitable for explosion-proof cameras. For example, oil-filled type, sand-filled type, etc., can not be used on explosion-proof cameras.

At present, the international mainstream of explosion-proof cameras is flameproof. It is characterized in that a conventional ordinary camera is placed in a special casing which has the function of isolating the spark and arc generated by the electrical components in the casing from the explosive mixture outside the casing, and is capable of withstanding the explosive mixture entering the casing. The explosion pressure generated by the sparks and arcs of the electrical equipment, and the outer casing is not destroyed; at the same time, it can prevent the explosive products in the shell from being blasted to the explosive mixture outside the shell, and will not cause the explosive mixture to burn and explode outside the shell. This kind of camera with a flameproof enclosure is an explosion-proof explosion-proof camera. And this special casing is called "explosion-proof casing", we usually call it "explosion-proof camera shield".

With the development of security field requirements and the improvement of the technology level of modern core chips and their components, intrinsically safe explosion-proof cameras are increasingly favored by the market.

The internal structure of the explosion-proof camera is strictly standard, in accordance with national standards, in line with the electrical equipment standards for explosive gas environment. Known as the "Security Special Forces." It has been widely used in the fields of safety production supervision and supervision value method equipment and functional area safety supervision value method capacity building in various provinces and cities.

2019-04-15 Yulangfang Longhe Science and Technology Achievement Incubation Park