LF signals clearly shows the broken wire edges and LMA shows the missing wire. Internal broken wire is observed in 32 mm diameter 6*36 wire rope configuration during its service. Loss of Metallic Cross-Sectional Area (LMA) - A relative measure of the amount of material (mass) missing from a location along the wire rope and is measured by comparing a point with a reference point on the rope that represents maximum metallic cross-sectional area, as measured with an instrument. Local Flaw (LF) - A discontinuity in a rope, such as a broken or damaged wire, a corrosion pit on a wire, a groove worn into a wire, or any other physical condition that degrades the integrity of the rope in a localized manner. LMA - To calculate the metallic cross sectional area, gives quantitative signals.LF - To identify the broken wires (Inner/Outer), gives qualitative signals. Two major sensor signals were used in this inspection as listed below Signals from the sensors are transmitted to an external basic unit for storage and further processing. These irregularities register by creating a signal in the sensors. When there are changes in ferrous cross section of the rope or broken wires occur, the magnetic field is distorted and flux leakage increases locally. Coils and/or Hall Effect sensors surround the rope and pick up the signal which is of a constant value. The magnetic field above the rope surface (flux leakage) remains uniform whilst the rope contains no irregularities. The inspection must consist of observation of wire ropes (running and standing) that are likely to be in use during the shift for apparent deficiencies. The rope portion inside the magnetic head is magnetically saturated with strong rare earth magnets in the longitudinal direction.
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