矿山井下IT配电系统绝缘监测的应用 Application of insulation monitoring of IT distribution system in mine

摘要：众所周知，能源作为经济发展的重要引擎，堪称是国民经济的命脉。采矿业一直是能源工业的重要支柱，我国的矿业生产主要来自井下开采，环境恶劣，就以煤矿为例，煤矿井下存在水、火、瓦斯、煤尘、顶板五大自然灾害，加上生产环境复杂，易发生恶性事故。出于**考虑，矿山井下低压配电系统按规定采用的是IT系统。IT系统就是电源中性点不接地、用电设备外露可导电部分直接接地（PE线）的系统。IT系统的特点是发生一次接地故障时，接地故障电流仅为非故障相对地的电容电流，其值很小，外露导电部分对地电压不过50V，不需要立即切断故障回路，因此可以保证供电的连续性。但此时非故障相对地电压会升高1.732倍，对线路耐压要求提升；同时一旦发生二次接地，则构成危险的相间短路，所以须配置绝缘监测装置，以便在发生一次接地时就要及时排除隐患。而对于以煤矿为典型代表的井下环境来说，在开采过程中，由于工作场所空间小、纵深长，加上空气潮湿、多尘、巷道滴水和积水等诸多恶劣因素，很容易引起电缆和电气设备老化和绝缘电阻下降，从而导致井下设备、电缆经常发生绝缘强度降低、单相漏电或单相接地故障，不及时处理就可能进一步发展成相间短路。因此，井下作业人员比正常环境下更容易遭受电击的危险，而且还可能导致瓦斯、煤尘的爆炸。
  显而易见，对矿山井下IT系统的实时绝缘监测具有更重要的意义。

As we all know, energy is an important engine of economic development and it is also the lifeblood of the national economy. The mining industry has always been the important pillar of the energy industry. China’s mining production mainly comes from underground where the environment is harsh.For example, there are five natural disasters: water, fire, gas, coal dust, and coal seam roof. In addition, the production environment is complex and it’s easy to cause the fatal accidents.
For safety reasons, the low-voltage power distribution system in the mine adopts an IT system. It is a system that neutral is ungrounded and conductive part of the load is directly grounded (PE line). The features of the IT system is that when the first grounding fault occurs, the current of grounding fault is very small, the voltage of exposed conductive part to ground is below 50V, It is unnecessary to cut off the fault circuit immediately, so it can ensure the continuity of power supply. But at this time, the voltage of non-fault relative to ground will increase by 1.732 times, and the requirement for line withstand voltage will increase. At the same time, once a secondary grounding occurs, it will lead to a dangerous phase-to-phase short-circuit, so an insulation monitoring device should be installed which can help eliminate hidden dangers in time when the first grounding occurs.For the coal mine as the typical representative of underground environment , in the process of mining, due to limited space, long in depth, humid air, dustiness, waterlogged roadway, and many other adverse factors, it is easy to cause the cable insulation resistance and electric equipment aging and decline, the underground equipment and cables often suffer from insulation strength reduction, single-phase leakage or single-phase grounding fault, If not handled in time, it may further develop into phase to phase short circuit. As a result, Underground workers are more vulnerable to electric shock than they would be in a regular environment, and may also cause explosion of gas and coal dust.

Obviously, It has more important significance for the real-time insulation monitoring of mine IT system.

2 .国内外绝缘监测仪在线监测现状

Online monitoring status of insulation monitors at home and abroad 

我国的电气设计在建国之初师从前苏联电气规范，主要是广泛的采用TN—C系统，它可以节省一根PE线，比较经济，但存在很多缺点，如中性线断裂后设备外壳对地将带220V危险接触电压，不能装用RCD防电击等等。改革开放之后我国引进了国际电工学会标准，也随着我国电气技术的不断提高，在应用中TN-S、TT、IT系统得到了一定程度的推广和应用，以IT系统为例，在医疗IT方面目前应用比较成熟，但在很多工业场合，由于对接地系统的理解和应用尚不尽深入，比如煤矿井下场合比较缺乏国产绝缘监测装置就是一个证明。目前矿用井下IT系统的绝缘监测装置以进口为主，欧美等发达国家已经较广泛地在IT配电网络中应用绝缘检测技术，而且经过长期的在线运行使发达国家积累了大量监测数据和经验，这是目前国内生产厂家需要学习和追赶的。

但采用进口绝缘监测装置造价昂贵，而且人机界面往往是英文，不利于现场人员的使用，在这种背景下，也不断有国内企业逐步推出了自己的工业用绝缘监测装置，其中就包括了安科瑞电气有限公司的AIM-T系列绝缘监测仪。

At the beginning of the founding of the People's Republic of China, China's electrical design was based on the former Soviet Union's electrical code, mainly using TN-C system . It can save a PE line, which is more economical, but there are many disadvantages, such as, after the neutral line breaks, the equipment shell to the ground will have a dangerous contact voltage of 220 V, and RCD cannot be installed to prevent electric shock, etc. After the reform and opening up, China has introduced the standards of IEC, and with the continuous improvement of electrical technology in China, TN-S, TT and IT systems have been promoted and applied to a certain extent. For example, the application in medical IT is relatively mature at present, but in many industrial occasions, due to the understanding and application of grounding system is not thorough and comprehensive, for example, the lack of domestic insulation monitoring device in coal mine is a proof.At present, the insulation monitoring devices of mine underground IT system are mainly imported brands.Insulation detection technology have been widely used in IT distribution network in developed countries such as Europe and the United States. And they have accumulated a lot of monitoring data and experience after a long-term online operation. This is what domestic manufacturers need to learn and catch up with.

However, it is expensive to use imported brand insulation monitoring devices, and the human-computer interface is often in English, which is not conducive to the use of field workers. There are also domestic enterprises which have gradually launched their own industrial insulation monitoring devices, including the AIM-T series insulation monitoring devices of Acrel.

3安科瑞工业绝缘监测仪

 Acrel industrial insulation monitor

                          AIM-T300 

                   AIM-T500

AIM-T500L

AIM-T系列绝缘监测仪主要应用在工业场所IT配电系统中，主要包括AIM-T300、AIM-T500和AIMT500L三款产品，均适用于纯交流、纯直流以及交直流混合的系统。
  其中AIM-T300适用于450V以下的交流、直流以及交直流混合系统，AIM-T500适用于800V以下的交流、直流以及交直流混合系。AIM-T500L则是相比AIM-T500增加了绝缘故障定位功能。

AIM-T series insulation monitor is mainly used in IT power distribution system of industrial site, including AIM-T300, AIM-T500 and AIM-T500L, which are all applicable to pure AC, pure DC and AC / DC hybrid systems.

AIM-T300 is suitable for AC, DC and AC / DC hybrid systems below 450V, and AIM-T500 is suitable for AC, DC and AC / DC hybrid systems below 800V. AIM-T500L has the function of insulation fault location compared with AIM-T500.

小结Summary
  安科瑞AIM-T系列工业用绝缘监测仪目前已经在矿井、纸业、船舶、冶金厂等的诸多工业场合的IT系统中得到了应用，能够实时监测系统对地的绝缘状况，在系统出现绝缘下降或接地故障时，及时报警提醒相关人员排查故障，在应用中起到了很好的监控和预防效果。

At present, Acrel AIM-T series industrial insulation monitor has been applied in the IT system of many industrial occasions, such as mine, paper industry, ship, metallurgy plant, etc. It can monitor the insulation condition of the system to the ground in real time. When the system has insulation drop or ground fault, it can alarm and remind relevant person to check the fault, which has a good monitoring and prevention effect in the application.