Eaton MTL MTL7758+ 7700 Series Digital Switch Safety Barrier ATEX Certified

The MTL7758+ is a high-performance 2-channel shunt-diode safety barrier (Zener barrier) from Eaton's Crouse-Hinds series MTL7700 range, specifically engineered for gas detectors and high-current/low-voltage applications requiring intrinsic safety protection in hazardous areas.

This passive device limits the voltage and current that can reach a hazardous area under fault conditions, preventing ignition of flammable atmospheres. With a rated supply voltage of 7.5V DC, safety description of 7.5V, 10 Ω, 750mA, and positive polarity configuration, the MTL7758+ is the ideal solution for protecting gas detectors, catalytic bead sensors, and other high-current field devices in Zone 0, 1, and 2 hazardous locations (gas groups IIC, IIB, IIA).

The device features a compact 12.6 mm width and standard DIN rail mounting for easy integration into existing control cabinets.

The "+" suffix indicates positive polarity, distinguishing it from the negative polarity version MTL7758-.

• Gas Detector Optimization: Specifically designed for gas detection applications — catalytic bead and infrared gas sensors requiring higher operating currents
• High-Current/Low-Voltage Design: Safety description of 7.5V, 10 Ω, 750mA — ideal for devices requiring up to 750mA at low voltage
• 2-Channel Efficiency: Two independent intrinsically safe channels in a single compact housing — protects two field devices while using minimal panel space
• Positive Polarity Configuration: Designed for positive ground applications — common in many industrial control systems
• IIC Gas Group Certification: Certified for the most hazardous IIC gas groups (hydrogen, acetylene) — suitable for use in Zone 0, 1, and 2 explosive atmospheres
• Removable Terminals: Unique removable terminal blocks for easy cabling, maintenance, and loop disconnect by simply unplugging terminals from the side of the module — a UNIQUE feature of the MTL7700 series
• Bussed Power Capability: Integrated bussed power distribution reduces cabling requirements — a UNIQUE feature of the MTL7700 series
• Angled Wire Entry: Wire entry is angled to assist wiring within limited space enclosures, making installation easier in crowded control cabinets
• Ultra-Slim DIN Rail Mounting: Compact 12.6 mm width for standard 35 mm T-section DIN rail — simultaneously makes a reliable IS earth connection when clipped onto the rail
• Dual-Stage Protection: Contains two stages of pulse-tested Zener or forward-connected diodes and an 'infallible' terminating resistor for maximum reliability
• Digital Output Range: Part of Eaton MTL's digital output range — designed for switching and power applications in hazardous areas
• Global Approvals: CCC Ex (China valid until 2030-09-01), ATEX, IECEx, CSA, FM certifications for international installation flexibility

Certificate 2020322316002402 is valid until September 1, 2030.

The MTL7758+ is a passive shunt-diode safety barrier that operates on the Zener barrier principle. It limits both voltage and current that can be delivered to a hazardous area circuit under fault conditions.

• Voltage limiting: Zener or forward-connected diodes clamp the output voltage to a safe level (7.5V) if the safe-area voltage rises above normal operating levels
• Current limiting: A series resistor (10Ω) limits fault current to a safe value (750mA)
• Fusing: A 200mA fuse protects the diodes, and the two stages of voltage limitation ensure continued safety if either stage should fail
• Positive polarity: The barrier is designed for positive ground applications — common in gas detector installations
• No active output current limiting circuits: Pure passive design for maximum reliability
• Grounding: The barrier requires a connection to a high-integrity earth ground — made simultaneously when clipping onto standard T-section DIN rail

The MTL7758+ is specifically designed for gas detection and high-current/low-voltage protection in hazardous area installations:

• Catalytic bead gas detectors (pellistor type) — requiring 200-300mA operating current
• Infrared (IR) gas sensors
• Electrochemical gas sensors
• High-current/low-voltage sensors and actuators
• Combustible gas detectors requiring higher power