Surge Arresters

Surge Arresters

Surge arresters (overvoltage protection devices) protect sensitive instrumentation and automation electronics from transient voltage events that can propagate through power and signal infrastructure. Direct and indirect lightning strikes, as well as switching operations within a process, can induce voltage overloads on supply lines and communication circuits, including fieldbus networks; even short disturbances can translate into production losses when critical measuring points or interfaces fail. Surge protection is therefore a foundational layer in designing for plant availability and reliable measurement.

The Endress+Hauser portfolio covers protection concepts matched to where the surge energy enters the system. Offerings include surge arresters for DIN-rail mounting in cabinets, field-mount devices near the instrument, and variants optimized for signal cables, fieldbus communication lines, and power lines. These devices are commonly applied in process automation and in measuring/communication technology across industries such as chemicals, pharmaceuticals, water and wastewater, and food processing.

The operating principle is controlled diversion of transient energy. Overvoltage surges appearing on signal cables (e.g., 4…20 mA), on fieldbus communication lines (HART, PA, FF), or on power conductors are routed safely to ground, preventing destructive stress on the connected electronics. The protection concept is intended to preserve the normal function of the instrumentation by using an impedance-free connection that avoids introducing interference voltage drops into the protected circuit.

Benefits include mounting flexibility (field or DIN rail), options with ATEX and SIL2 intrinsically safe approvals, and protection solutions aligned to typical process automation electronics to improve overall availability. Typical applications include outdoor measurement points and long cable runs exposed to lightning and switching transients, cabinet interfaces where instrument loops enter I/O systems, and mixed analog/fieldbus installations where a common grounding strategy is required. Effective use pairs the arrester selection with a low-impedance bonding and grounding design so surge currents have a defined path that does not compromise signal integrity.

Miller Mechanical Specialties, an exclusive authorized representative of sales and service for Endress+Hauser.