Pepperl+Fuchs Z786 Zener barrier intrinsically safe

The Pepperl+Fuchs Z786 is a high-performance Zener barrier designed for intrinsically safe (IS) applications, providing robust protection for 4-20 mA analog signals in hazardous areas classified under Zone 1/21 and Zone 2/22. It ensures safe signal transmission between field devices (like sensors/transmitters) and control systems by limiting voltage and current to non-incendive levels in explosive atmospheres.

Key Features of the Z786 Zener Barrier

✔ Single-Channel (1-Channel) Isolation – Protects one 4–20 mA loop.

✔ Advanced Zener Diode Protection – Complies with Ex ia IIC / Ex ib IIC standards.

✔ Global Certifications:

ATEX / IECEx (Ex ia IIC T6 Ga / Ex ib IIC T6 Gb)

FM / CSA (Class I, II, III, Div. 1)

UKCA / EAC (TR CU) for regional compliance.

✔ Wide Input Voltage Range: 10–30V DC (flexible power supply options).

✔ LED Status Indicators – Real-time monitoring of power and fault conditions.

✔ Compact & Robust Design – DIN-rail mountable (35mm rail) with high EMI immunity.

Typical Applications

Oil & gas refineries (pressure/flow transmitters).

Chemical & pharmaceutical plants (hazardous area instrumentation).

Mining & bulk material handling (dusty environments).

Power plants (temperature monitoring in Ex zones).

Wiring & Installation

Safe Area (Control System Side)

Terminal 1 (+Ub): Power supply (10–30V DC).

Terminal 2 (GND): Mandatory earth ground (low-impedance connection critical!).

Terminal 3 (OUT): Signal output to PLC/DCS.

Hazardous Area (Field Side)

Terminal 4 (IS+): Intrinsically safe output to field device.

Terminal 5 (IS–): Return line from field device.

⚠ Critical Safety Notes:

Grounding must be <1 Ω resistance – Zener barriers rely on proper earthing for safety.

Use shielded cables in noisy environments.

Do NOT use in Zone 0 without verification (Ex ia required for Zone 0).

Comparison with Similar Barriers

Model Type Channels Key Difference

Z786 Zener Barrier 1 4–20 mA, wide voltage (10–30V DC)

KFD2-SR2-Ex2 Galvanic Isolator 2 No ground dependency, higher cost

LB8521 Loop-Powered Barrier 1 For 2-wire transmitters

Why Choose the Z786?

✅ Global hazardous area certifications (ATEX, IECEx, FM, CSA).

✅ Reliable signal integrity with EMI-resistant design.

✅ Easy DIN-rail integration for control panels.