signalsløyfer

Signalsløyfer are electrical loops used in signaling systems to detect the presence of rolling stock or to activate signals and interlocking logic. The term is used in Norwegian railway engineering and related signaling contexts. A signalsløyfe consists of a loop of conductor, often buried under ballast, track, or pavement, connected to a signaling controller. When a metal object such as a train wheel or vehicle passes near or over the loop, the loop’s inductive properties or impedance change, and this change is read by the controller to update a signal, detector input, or interlocking state.

In railway applications, signalsløyfer are part of occupancy detection and control circuits, helping to determine whether a track section is clear. They can be arranged in single or multiple turns to achieve the required sensitivity and reliability, and are designed to withstand moisture, mechanical wear, and environmental conditions. In road traffic, inductive signalsløyfer embedded in the pavement serve as vehicle detectors for traffic signals, pedestrian crossings, tolling systems, or ramp metering.

Installation requires careful placement to avoid interference from nearby metal structures, proper sealing against moisture, and durable electrical connections. Regular maintenance involves cleaning, testing insulation and connections, and monitoring for corrosion or damage. Signalsløyfer provide robust, low-maintenance operation with no moving parts, but performance can degrade if loops are damaged, obstructed, or exposed to significant ground moisture or debris.