Description
Eaton MTL 778ac Shunt-Diode Safety Barrier
MTL7700 Series Intrinsic Safety Barrier — 2-Channel (AC/DC)
This Eaton MTL 778ac safety barrier is in excellent, clean used condition. It was carefully pulled from a working, dust-free decommissioned system cabinet. The housing, integrated DIN-rail earth ground connections, and wire terminal clamping screws are fully intact and in perfect working order.
Product Overview
The Eaton MTL 778ac (manufactured by Measurement Technology Ltd.) is an ultra-reliable, DIN-rail mounted shunt-diode intrinsic safety barrier. It is designed to act as an energy-limiting protector between control room equipment (safe area) and field instrumentation located in explosive or hazardous atmospheres (hazardous area).
Featuring a 2-channel design, the MTL 778ac limits electrical energy (voltage and current) to levels well below what is required to ignite flammable gas or dust mixtures. It is particularly well-suited for alternating current (AC) signals, thermocouple lines, RTD temperature sensors, and low-level transmitter loops.
Technical Specifications
| Specification Parameter | Details |
|---|---|
| Brand / Manufacturer | Eaton / MTL (Measurement Technology Ltd.) |
| Model / Part Number | MTL 778ac |
| Series Reference | MTL 7700 Series |
| Number of Channels | 2 Independent Channels (AC / DC) |
| Nominal Resistance | 28V — 300Ω / 28V — 28kΩ (approx.) |
| Safety Standard | Intrinsically Safe (IS) / Explosion-Proof (Ex) |
| Mounting Style | Standard 35mm DIN Rail (with integrated earth grounding contact) |
| Housing Color | Industrial Gray with Black terminal hoods |
Key Features
- Dual-Channel Density: Houses two completely independent safety-barrier channels inside an ultra-slim 12.6mm housing profile to save valuable cabinet footprint.
- Passive Solid-State Circuitry: Relies on robust zener diodes, resistors, and fast-acting fuses, requiring no external supply power to operate.
- Integrated Earth Connection: Automatically grounds to the mounting DIN rail via standard busbar contacts, removing the need for auxiliary ground wiring.
- High-Accuracy Signal Pass: Engineered to minimize loop impedance errors, preserving critical analog measurement and communication accuracy.

