The NR4200 series cable identifier is a special instrument used to identify a specific cable from a bunch of cables in power cable erection, migration maintenance and troubleshooting. When identifying a specific cable, it not only uses the current direction as the standard, but also uses the current amplitude value as the judgment standard. This double judgment standard is more likely to identify the cable reliably and accurately. The instrument is a miniaturized portable, compact device, housed in an aluminum alloy box, composed of a generator, a receiver with a caliper, and cables.