Surge Arresters

Surge Arresters

Surge arresters (overvoltage protectors) safeguard sensitive electronics by diverting transient energy away from instruments and control equipment. Installed in power supply lines and signal/communication circuits, they prevent voltage spikes from damaging transmitters, indicators, and network components. In practical terms, they turn an unpredictable external event into a controlled discharge path to ground, preserving measurement continuity and device integrity.

Transient overvoltage can be introduced by direct or indirect lightning as well as switching operations within a plant. These events can couple into supply lines and communication circuits - including fieldbus networks - creating overloads that may last only moments but still disrupt production. A complete protection concept therefore includes devices suited for DIN‑rail installation in cabinets, field mounting near the instrument, and protection targeted specifically at signal cables, fieldbus lines, and power lines.

Functionally, surge arresters provide a low‑impedance route for overvoltage surges to be safely passed into the ground. The intent is to protect electronic components in field devices while leaving normal measurement and communication behavior unaffected. An impedance‑free connection helps avoid introducing interference voltage drops into the circuit, which is essential for maintaining signal quality on 4–20 mA loops and digital fieldbuses (HART, PA, FF).

The benefit is increased availability through reduced instrument failures and fewer nuisance trips after electrical disturbances. Product variants cover different installation styles and circuit types (power, analog signals, and communication lines), so protection can be matched to the topology rather than forced into a one-size-fits-all approach. Where required, options with hazardous-area approvals and SIL-related considerations support use in intrinsically safe and safety-instrumented environments.

Typical applications include protecting 4–20 mA transmitter loops, fieldbus segments, and cabinet power feeds in areas prone to lightning exposure or heavy switching loads. They are widely used in process automation and measuring/communication technology where field devices are distributed over large footprints and cable runs are long, increasing the likelihood of transient coupling.

Field Instruments & Controls, Inc. an exclusive authorized representative of sales and service for Endress+Hauser.