| 摘要 |
A sensor (1) for use in machine wear debris monitoring transducers which detect metallic particles (12) present in a flow of fluid, such as lubricating oil. The sensor (1) comprises an inductive coil (2) having a plurality of turns for surrounding a non-magnetic conduit (8). An electrically conducting screen (14) is located between the coil and the flow of fluid (9), the coil being electrically insulated from the screen, so as to isolate capacitatively the contents of the conduit (8) from the coil (2). The resonant frequency of a tank circuit incorporating the sensor (1) is thus unaffected by changes in the dielectric properties of the contents of the conduit caused by air bubbles and/or water droplets (10) in the flow of fluid. The screen (14) may be a single turn of thin metal foil having a gap between adjacent ends, or a mesh, or a metallic coating sprayed onto the conduit.
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