广州发电厂3号汽轮机轴向位移测量装置受干扰的分析与处理

Analysis and Treatment on Interference to Axial Displacement Measurement Device of No.3 Turbine in Guangzhou Power Plant

针对广州发电厂3号汽轮机轴向位移测量装置受对讲机干扰的问题,从电磁干扰源、传播耦合途径和敏感设备3个方面分析干扰的特性,并通过干扰测试排除了信号电缆受电磁干扰的可能,确认前置器外壳未接地是测量装置受干扰的主要原因,提出以屏蔽方法切断高频电磁波干扰耦合途径较切合实际。现场采取了将延伸电缆置于屏蔽体内、降低前置器高频接头接触电阻等措施,取得了良好的效果,轴向位移跳变幅度由1.371mm降至0.033mm。

Aiming at walkie talkie's interference to axial displacement measurement device of No.3 turbine in Guangzhou power plant,this paper analyzes characteristics of the interference from three aspects—source of electromagnetic interference,coupling path for transmission and sensitive devices.Also,it rules out the possibility that the signal cables are affected by electromagnetic interference and conforms that the principal cause for interference to measurement device lies with the absence-of-ground proximitor shell.The paper illustrates practicability to block high-frequency electromagnetic interference with shielding method.Measures that inlaying the extension cable into the shielding enclosure,reducing the contact resistance of proximitor's high-frequency terminal have been adopted and favorable results have been attained.The step amplitude of axial displacement falls from 1.371 mm to 0.033 mm.