Signal, Data & Loop

Choosing the right device

Low-voltage signal wiring — 4–20 mA instrument loops, alarm and fire circuits, SCADA telemetry — is the most surge-sensitive wiring in a facility, and protection must be matched to the signal or it will interfere with it. Choose a breakdown voltage comfortably above your peak signal voltage, and check series resistance against what your loop can tolerate.

DIN-rail modules like the DRS series drop into control panels and add self-restoring sneak-current protection, while field-mount units protect instruments at the point of exposure. Water and wastewater plants are the classic application — that's what the SLAC series was designed for — but the same devices protect any panel-mounted instrumentation. Questions about a specific loop? A licensed electrician answers at 941-355-8822.