Pepperl+Fuchs WE77-EX1 Intrinsically Safe Switch Amplifier

The WE77/Ex-1 115V Intrinsically Safe Switch Amplifier from Pepperl+Fuchs is a 1-channel intrinsically safe isolated barrier that provides galvanic isolation between input, output, and power supply for safe digital signal transfer in hazardous-area process automation. It interfaces NAMUR sensors or mechanical contacts with control systems, using an EEx ia IIC input circuit and a SPDT relay output rated 253 VAC / 2 A / 500 VA. The unit operates from 103.5 to 126 VAC at 45–65 Hz, with open-circuit voltage around 8 VDC and short-circuit current near 8 mA, and a switching frequency of less than 10 Hz; lead-breakage monitoring is included, and operating modes can be reversible or non-reversible. Galvanic isolation protects input from output and from the power supply, while the IP20 enclosure and DIN rail mounting suit industrial installations. Physicals include a footprint of 40 × 104 × 110 mm, weight approximately 390 g, and an operating temperature range of −20°C to +60°C. Certifications include ATEX, cULus, and CE, with standards compliance to EN 60947-5-6, IEC/EN 61010-1, and EN 60079-11. Common replacements listed for this device include Pepperl+Fuchs KFA5-SR2-Ex1.W and KFD2-SR2-Ex1.W, as well as WE77/Ex-2 115V variants.