Surge Arresters

Surge Arresters

Surge arresters are protective interface components designed to prevent damaging overvoltage events from reaching sensitive electronics in instrumentation and communication circuits. They address both external surge sources (such as lightning-induced transients) and internal sources (such as switching events) that can couple energy into signal and power wiring.

These devices are applied to power lines, 4–20 mA signal cables, and digital communication lines—including common fieldbus interfaces—by providing a controlled path for surge energy to be diverted safely to ground. Properly implemented, the protected circuit continues to function normally under standard conditions, with the arrester acting only during transient events.

Benefits are primarily measured in avoided failures: fewer transmitter and I/O card replacements, reduced nuisance downtime, and improved overall availability. Because surges can damage devices silently or intermittently, well-matched protection can also reduce hard-to-diagnose reliability issues that manifest as sporadic faults.

Surge arresters are available in form factors suitable for cabinet (DIN rail) installation and for mounting closer to field devices. Selecting the appropriate protection topology and installation location is typically guided by the exposure profile (e.g., outdoor runs), grounding strategy, and the type of circuit to be protected.

Typical applications include process automation networks, measurement loops on long cable runs, and installations with elevated lightning or switching-transient risk—especially where fieldbus integrity is critical. Selection considerations include circuit type (power vs. signal vs. bus), mounting location, and any required approvals such as intrinsic safety or functional safety ratings.

Vector, your Authorized Endress+Hauser Representative.