矿井无线电波防爆安全发射功率研究

Research on the safe transmission power of mine radio wave explosion prevention

  • 摘要: 5G,5.5G,WiFi6,WiFi7,UWB,ZigBee等矿井移动通信系统及人员和车辆定位系统等发射的大功率无线电波有点燃瓦斯和煤尘的风险。因此,需要合理设置防爆无线电设备发射的无线电波防爆安全功率阈值,限制防爆无线电设备发射的无线电波功率。欧洲标准CLC/TR 50427:2004《Assessment of inadvertent ignition of flammable atmospheres by radio-frequency radiation-Guide》规定了爆炸性气体环境中无线电波防爆安全接收点火功率阈值,但缺少无线电波防爆安全发射功率阈值的内容。国家标准GB/T 3836.1—2021《爆炸性环境 第1部分:设备 通用要求》和国际标准IEC 60079-0:2017《Explosive atmospheres-Part 0:Equipment-General requirements》虽然有无线电波防爆安全发射功率阈值的相关规定,但错误地将欧洲标准CLC/TR 50427:2004中的无线电波防爆安全接收点火功率阈值修改为无线电波防爆安全发射功率阈值,大大降低了爆炸性环境中无线电设备所能允许的最大发射功率。由于煤矿井下没有能作为接收天线的起重机这类细长结构物体,且现有矿井无线通信及定位系统工作频率均远大于30 MHz,所以,无线电波防爆安全接收点火功率阈值应为8 W,而不是国家标准GB/T 3836.1—2021和国际标准IEC 60079-0:2017规定的无线电波防爆安全发射功率阈值6 W。在发射天线发射的无线电波能量全部被等效天线吸收的最不利于无线电防爆的传输和耦合情况下,无线电设备工作频率为等效天线谐振频率时,接收点火功率达到最大,为等效天线接收的总功率的一半,即发射功率的一半。在实际工程中,无线传输效率和耦合效率均不会为1,因此,无线电波防爆安全发射功率阈值应是无线电波防爆安全接收点火功率阈值2倍以上。煤矿井下无线电波防爆安全接收点火功率阈值为8 W,因此,煤矿井下无线电波防爆安全发射功率阈值应大于16 W。

     

    Abstract: High power radio waves emitted by mobile communication systems such as 5G, 5.5G, WiFi6, WiFi7, UWB, ZigBee, as well as personnel and vehicle positioning systems in mines, pose a risk of igniting gas and coal dust. Therefore, it is necessary to set a reasonable threshold for the explosion-proof safe power of radio waves emitted by explosion-proof radio equipment, and limit the power of radio waves emitted by explosion-proof radio equipment. The European standard CLC/TR 50427:2004 Assessment of inadvertent ignition of flammable atmospheres by radio-frequency radiation-Guide specifies a threshold for the safe reception and ignition power of radio waves in explosive gas environments. But it lacks content on the threshold for the safe transmission power of radio waves. Although the national standard GB/T 3836.1-2021 Explosive atmospheres-Part 1:Equipment-General requirements and the international standard IEC 60079-0:2017 Explosive atmospheres-Part 0:Equipment-General requirements have relevant provisions on the safe transmission power threshold for radio wave explosion protection, they mistakenly modify the safe reception ignition power threshold for radio wave explosion protection in the European standard CLC/TR 50427:2004 to the safe transmission power threshold for radio wave explosion protection. It greatly reduces the maximum transmission power allowed by radio equipment in explosive atmospheres. There’s a lack of slender structural objects such as cranes that can serve as receiving antennas in coal mines. The existing radio communication and positioning systems in mines operate at frequencies far greater than 30 MHz. Therefore, the threshold for the safe reception and ignition power of radio waves should be 8 W, instead of the radio wave explosion-proof safe transmission power threshold of 6 W specified in the national standard GB/T 3836.1-2021 and the international standard IEC 60079-0:2017. When the energy of the radio waves emitted by the transmitting antenna is fully absorbed by the equivalent antenna, which is the most unfavorable for wireless explosion-proof transmission and coupling, and the operating frequency of the radio equipment is the equivalent antenna resonance frequency, the reception and ignition power reaches its maximum. It is half of the total power received by the equivalent antenna, that is, half of the transmission power. In practical engineering, both radio transmission efficiency and coupling efficiency are not equal to 1. Therefore, the threshold for safe transmission power of radio waves should be more than twice the threshold for safe reception and ignition power of radio waves. The threshold for the safe reception and ignition power of underground radio waves in coal mines is 8 W. Therefore, the threshold for the safe transmission power of underground radio waves in coal mines should be greater than 16 W.

     

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