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目前,对于管道内部腐蚀的在线监测,最先进的商用系统是基于FSM(Field Signature Method)开发的,可以实现不需要在管道打洞,非破坏式的监测。但是现有设备通常采用直流电流源激励,存在信噪比低,易引起电火花,电缆较粗等诸多缺点。针对上述问题,本文采用交流激励电流源和锁相放大技术进行设计开发,对采集的微弱电压信号先进行前置放大,在达到足够的电平等级后,再推动锁相放大器进行锁相放大,去除所有不同频率的干扰。实验表明,本文所述的设计在信噪比、精度和稳定性上满足项目要求,可以很好地避免现有的基于直流激励技术的FSM设备所存在的问题。
At present, the most advanced commercial system for on-line monitoring of corrosion inside a pipeline is developed based on the Field Signature Method (FSM), which enables drilling without holes and non-destructive monitoring. However, the existing equipment usually adopts the direct current source excitation, which has the disadvantages of low signal-to-noise ratio, easy to cause electric spark, and thicker cables. In view of the above problems, this paper uses AC excitation current source and phase-locked amplification technology for design and development, the acquisition of the weak voltage signal first pre-amplification, after reaching a sufficient level, and then promote the lock-in amplifier for phase lock amplification, Remove all the different frequencies of interference. Experiments show that the design described in this paper meets the project requirements in signal-to-noise ratio, accuracy and stability, and can well avoid the existing problems of the existing FSM equipment based on DC excitation technology.