Eaton MTL7764AC Zener Safety Barrier 12V 1000Ω ATEX Approved for Hazardous Areas
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Product Description
Eaton MTL MTL7764AC Zener Safety Barrier 12V 1000Ω ATEX Approved Hazardous Area
Product Overview
The MTL7764AC is a high-performance shunt-diode safety barrier (Zener barrier) from Eaton's Crouse-Hinds series MTL7700 range, specifically engineered for strain-gauge bridge circuits, load cells, and Wheatstone bridge 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 voltage of 12 V, end-to-end resistance of 1,000 Ω, and maximum current of 12 mA, the MTL7764AC is the ideal solution for protecting sensitive strain-gauge based measurement equipment in Zone 0, 1, and 2 hazardous locations (gas groups IIC, IIB, IIA).
The device features a compact 12 mm width and standard DIN rail mounting for easy integration into existing control cabinets.
Model Number Decoding: MTL7764AC
| Code Segment | Meaning |
|---|---|
| MTL | MTL Instruments Group (now Eaton) |
| 77 | MTL7700 series — Shunt-diode safety barriers |
| 64 | Specific barrier configuration for strain-gauge bridges |
| AC | AC/DC compatible — suitable for both AC and DC circuits |
The "AC" suffix indicates compatibility with AC circuits, distinguishing it from polarity-sensitive models.
Key Features & Benefits
Strain-Gauge Bridge Optimization: Specifically designed for strain-gauge bridge circuits and load cell applications
12 V Working Voltage: Provides safe voltage limiting for strain-gauge bridge circuits
1,000 Ω End-to-End Resistance: Matches impedance requirements of typical strain-gauge bridge circuits
12 mA Maximum Current: Adequate current handling for strain-gauge bridge excitation
AC/DC Compatibility: Suitable for both AC and DC circuits — no polarity concerns
Ultra-Slim DIN Rail Mounting: Compact 12 mm width saves valuable panel space
High Accuracy Signal Transfer: Minimal signal distortion for sensitive measurements
Multiple International Approvals: ATEX, TIIS, and Factory Mutual certifications
Technical Specifications
General Specifications
| Parameter | Value |
|---|---|
| Manufacturer | Eaton (Crouse-Hinds series MTL) |
| Series | MTL7700 Range |
| Product Model | MTL7764AC |
| Alternative Part Number | 5710-032-006 |
| Product Type | Shunt-Diode Safety Barrier (Zener Barrier) |
Electrical Ratings
| Parameter | Value |
|---|---|
| Working Voltage (Vwkg) | 12 V |
| Maximum Current | 12 mA |
| End-to-End Resistance | 1,000 Ω |
| Resistance Tolerance | ±10 % |
| Fuse Rating | 50 mA |
| Number of Channels | 1 (single-channel) |
| Polarity | AC (non-polarized) |
Hazardous Area Specifications
| Parameter | Value |
|---|---|
| Gas Groups | IIC, IIB, IIA |
| Zones | Zone 0, 1, 2 |
| Safety Description | 12 V, 1,000 Ω, 12 mA |
Mechanical Specifications
| Parameter | Value |
|---|---|
| Width | 12 mm |
| Height | 86 mm |
| Length/Depth | 105 mm |
| Weight | 100 g / 0.121 kg |
| Enclosure Material | Polycarbonate |
| Mounting | DIN rail (35 mm) |
| Terminals | Screw terminals |
Function Description
The MTL7764AC 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.
How it works:
- Voltage limiting: Zener diodes clamp the output voltage to a safe level (12 V) if the safe-area voltage rises above normal operating levels
- Current limiting: A series resistor (1,000 Ω) limits fault current to a safe value (12 mA)
- Fusing: Internal 50 mA fuses provide backup protection under severe fault conditions
- Grounding: The barrier requires a connection to a high-integrity earth ground to function properly
Typical strain-gauge bridge configuration:
- The MTL7764AC is typically used in conjunction with other MTL barriers for complete strain-gauge bridge protection:
- MTL7761ac: Provides bridge excitation power (14 V, 230 Ω source)
- MTL7764ac: Used to sense the bridge supply voltage
- MTL7766Pac: Provides 12.3 V for 350 Ω bridges with 20 V supply
- For load cells with resistance between 350 Ω and 800 Ω, the MTL7764AC provides safe excitation and signal conditioning
Load cell application note:
The MTL7764AC is approved by Factory Mutual for use with 1 to 4 load cells in a clear covered polycarbonate junction box. The indicator can have excitation voltage of 10 to 20 V DC and must have remote sense ability. Load cells with Wheatstone bridge circuits are classified as "Non-energy Storing Simple Apparatus" (per ANSI/ISA-RP12.6) requiring no additional approvals when connected to certified intrinsic safety barriers.
The MTL7764AC is approved by Factory Mutual for use with 1 to 4 load cells in a clear covered polycarbonate junction box. The indicator can have excitation voltage of 10 to 20 V DC and must have remote sense ability. Load cells with Wheatstone bridge circuits are classified as "Non-energy Storing Simple Apparatus" (per ANSI/ISA-RP12.6) requiring no additional approvals when connected to certified intrinsic safety barriers.
Applications
The MTL7764AC is specifically designed for strain-gauge and load cell applications in hazardous area installations:
| Industry | Application |
|---|---|
| Oil & Gas | Tank level measurement using load cells on storage tanks in Zone 0/1 areas |
| Chemical Processing | Vessel weighing systems, hopper scales, and silo level monitoring |
| Pharmaceutical | Batch weighing systems for solvent handling equipment requiring Ex protection |
| Mining | Conveyor belt weighing systems, bin level monitoring |
| Food & Beverage | Tank weighing for flammable liquid storage (spirits, oils) |
| Marine & Offshore | Cargo tank monitoring, mooring line tension measurement |
Typical field devices connected:
- Strain-gauge bridge sensors (full Wheatstone bridge configuration)
- Load cells (350 Ω to 800 Ω resistance)
- Torque sensors
- Pressure sensors based on strain-gauge technology
- Weighing systems in hazardous areas
Why Choose the MTL7764AC?
Optimized for Strain-Gauge Bridges
Unlike general-purpose safety barriers, specifically designed for strain-gauge bridge circuits and load cells
Unlike general-purpose safety barriers, specifically designed for strain-gauge bridge circuits and load cells
AC/DC Flexibility
Non-polarized operation eliminates wiring errors and simplifies installation
Non-polarized operation eliminates wiring errors and simplifies installation
Proven MTL7700 Series Reliability
Industry standard for shunt-diode safety barriers for decades
Industry standard for shunt-diode safety barriers for decades
Global Approvals
Certified for use in major industrial markets worldwide
Certified for use in major industrial markets worldwide
Simple Installation
DIN rail mounting, clearly labeled terminals, and compact design
DIN rail mounting, clearly labeled terminals, and compact design
Load Cell System Compatibility
Factory Mutual approved for use with 1 to 4 load cells
Factory Mutual approved for use with 1 to 4 load cells
MTL7764AC vs. Related MTL7700 Series Models
| Model | Working Voltage | Current | Resistance | Polarity | Application |
|---|---|---|---|---|---|
| MTL7764AC | 12 V | 12 mA | 1,000 Ω | AC | Strain-gauge bridges, load cells |
| MTL7760ac | 7 V | 72 mA | 85 Ω | AC | General purpose AC circuits |
| MTL7761ac | 10 V | 93 mA | 300 Ω | AC | AC circuits, general purpose |
| MTL7761Pac | 10 V | 93 mA | 300 Ω | AC | Power bus version |
| MTL7765ac | 12 V | 93 mA | 300 Ω | AC | AC circuits, higher current |
| MTL7766ac | 14 V | 93 mA | 300 Ω | AC | AC circuits, higher voltage |
| MTL7766Pac | 14 V | 93 mA | 300 Ω | AC | Power bus version, 12.3 V for 350 Ω bridge |
Installation Information
| Parameter | Detail |
|---|---|
| Mounting | Standard 35 mm DIN rail (EN 60715) |
| Terminals | Screw terminals (accepts up to 2.5 mm² wire) |
| Grounding | Requires high-integrity earth ground connection |
| Clearance | Minimal — 12 mm width enables high-density installation |
| Operating Position | Any orientation |
Important Installation Notes:
- A high-integrity earth ground connection is mandatory for proper Zener barrier operation
- Do not install in areas where condensation may occur
- The barrier must be installed in a safe area (non-hazardous location)
- Maximum cable parameters for IIC gas group apply to field wiring
- For load cell applications, ensure the indicator has remote sense capability
Compliance & Certifications
| Certification | Status | Details |
|---|---|---|
| ATEX | Certified | BAS01 ATEX 7217 — II (1) GD [Ex ia] IIC |
| TIIS (Japan) | Certified | TC16441 (expired July 2024, renewal available) |
| Factory Mutual (FM) | Approved | For load cell applications with 1-4 load cells |
| CSA | Certified | North American approval |
| RoHS | Compliant | Lead-free |
| CE | Compliant | EMC Directive |
Related Products from MTL7700 Series for Strain-Gauge Applications
| Model | Function | Description |
|---|---|---|
| MTL7761ac | Excitation Supply | 10 V, 300 Ω source for bridge excitation |
| MTL7764ac | Bridge Sense | 12 V, 1,000 Ω, 12 mA — senses bridge supply voltage |
| MTL7766Pac | Bridge Power | 14 V, 300 Ω — provides 12.3 V for 350 Ω bridge |
| MTL7761Pac | Power Bus Version | Same as MTL7761ac with power bus capability |
| MTL7706+ | Single-Channel Barrier | 28 V, 93 mA, 300 Ω — general purpose positive polarity |
| MTL7787+ | Dual-Channel Barrier | 28 V, 93 mA, 300 Ω — general purpose positive polarity |
The MTL7700 series offers a complete range of shunt-diode safety barriers for all intrinsic safety applications.
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Company
Shenzhen Hengyo Power Technology Co., Limited
Location
Room 2407, B Block No.145 Chengshi Zhuchang Bld, Bagua 2nd Rd, Futian Dist. Shenzhen City, China 518029
Contact Person
Vivian Chan