MTL7755AC Eaton MTL RTD Zener Safety Barrier
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negotiable
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Delivery Time:
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Brand:
Eaton
Product Description
MTL7755AC Eaton MTL RTD Zener Safety Barrier
Product Overview
The MTL7755AC is a high-performance 2-channel shunt-diode safety barrier (Zener barrier) from Eaton's Crouse-Hinds series MTL7700 range, specifically engineered for 2-wire and 3-wire floating bridge RTD 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 safety description of 3V, 10 Ω, 300mA, the MTL7755AC is the ideal solution for protecting Pt100, Pt500, and Pt1000 RTD sensors in Zone 0, 1, and 2 hazardous locations (gas groups IIC, IIB, IIA).
Model Number Decoding
| Code Segment | Meaning |
|---|---|
| MTL | MTL Instruments Group (now Eaton) |
| 77 | MTL7700 series — Shunt-diode safety barriers |
| 55 | Specific barrier configuration for floating RTD applications |
| AC | Non-polarized, AC/DC compatible configuration |
The "AC" suffix indicates a non-polarized barrier suitable for both AC and DC circuits, distinguishing it from polarity-sensitive models. This model is specifically designed for 2-wire and 3-wire RTDs (floating bridge).
Key Features & Benefits
- 2-Channel Efficiency: Two independent intrinsically safe channels in a single compact housing — protects two RTD sensors while using minimal panel space
- Floating RTD Optimization: Specifically designed for floating bridge RTD applications — ideal for Pt100, Pt500, Pt1000 2-wire and 3-wire RTD temperature sensors
- Low-Voltage/High-Current Design: Safety description of 3V, 10 Ω, 300mA — perfect for low-voltage temperature sensing applications requiring higher current
- 2-Wire or 3-Wire RTD Support: Flexible configuration for 2-wire or 3-wire RTD connections — compensates for lead resistance for accurate temperature measurement
- AC/DC Compatibility: Non-polarized operation eliminates wiring errors — no need to worry about positive or negative polarity connections
- Removable Terminals: Unique removable terminal blocks for easy cabling, maintenance, and loop disconnect by simply unplugging terminals from the side of the module
- Bussed Power Capability: Integrated bussed power distribution reduces cabling requirements
- 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: Each channel contains two stages of pulse-tested Zener or forward-connected diodes and an 'infallible' terminating resistor
- Direct Replacement for Obsolete Models: Compatible terminal numbering and safety descriptions allow direct replacement of older barriers: MTL105, MTL155, MTL156, MTL755AC
- Global Approvals: CCC Ex (China valid until 2030-09-01), ATEX (BAS01 ATEX 7217), IECEx, UL, CSA certifications for international installation flexibility
Technical Specifications
General Specifications
| Parameter | Value |
|---|---|
| Manufacturer | Eaton (Crouse-Hinds series MTL) |
| Series | MTL7700 Range |
| Product Model | MTL7755AC |
| Product Type | Zener Barrier (Shunt-Diode Safety Barrier) |
| Number of Channels | 2 (dual-channel) |
| Polarity | AC (non-polarized) |
Electrical Ratings
| Parameter | Value |
|---|---|
| Safety Description | 3 V, 10 Ω, 300 mA |
| Rated Supply Voltage DC | 3 V DC |
| End-to-End Resistance | 10 Ω |
| Maximum Current | 300 mA |
| Fuse Rating | 250 mA |
| Maximum Safe Area Voltage | 250 V AC/DC |
| Typical Application | 2- or 3-wire RTD (floating bridge) |
Hazardous Area Specifications
| Parameter | Value |
|---|---|
| Gas Groups | IIC, IIB, IIA |
| Zones | Zone 0, 1, 2 |
| NEC Hazardous Rating | Class I, Division 2; Class I, Zone 2 |
| ATEX/IECEx Rating | II (1) GD [Ex ia] IIC |
| ATEX Certificate | BAS01 ATEX 7217 |
| Ingress Protection | IP20 |
Mechanical Specifications
| Parameter | Value |
|---|---|
| Width | 12 mm - 12.6 mm |
| Height | 87 mm - 90 mm |
| Depth/Length | 105 mm - 106 mm |
| Weight | 0.106 kg - 0.200 kg |
| Enclosure Material | Polycarbonate |
| Mounting | 35 mm T-section DIN rail (EN 60715) |
| Terminals | Removable screw terminals, colour-coded |
Environmental Specifications
| Parameter | Value |
|---|---|
| Minimum Operating Temperature | -20°C |
| Maximum Operating Temperature | +60°C to +65°C |
| Degree of Protection | IP20 |
Certifications & Approvals
| Certification | Status | Certificate Number | Region |
|---|---|---|---|
| CCC Ex (China) | Current (to 2030-09-01) | 2020322316002401 | China |
| ATEX | Certified | BAS01 ATEX 7217 | Europe |
| IECEx | Certified | -- | International |
| UL | Certified | -- | USA |
| CSA | Certified | -- | North America |
| TIIS (Japan) | Expired (2024-07-02) | TC16450 | Japan |
TIIS certification expired July 2, 2024. CCC Ex certification is valid until September 1, 2030.
Function Description
The MTL7755AC 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 or forward-connected diodes clamp the output voltage to a safe level (3V) if the safe-area voltage rises above normal operating levels
- Current limiting: A series resistor (10Ω) limits fault current to a safe value (300mA)
- Fusing: A 250mA fuse protects the diodes, and the two stages of voltage limitation ensure continued safety if either stage should fail
- Floating bridge configuration: Specifically designed for 2-wire and 3-wire RTDs with floating bridge topology
- AC/DC compatibility: The "AC" suffix indicates non-polarized operation for both AC and DC circuits
- 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
Safe Area (Control Side) Hazardous Area (Field Side)
PLC/DCS/RTD Input ──► MTL7755AC ──────────► Intrinsically safe circuit
3V DC supply ──► (Voltage/Current limiting) ──► 2- or 3-wire RTD (Pt100)
(Zener diodes + 10Ω resistor) Floating Bridge Sensor
[Non-polarized AC configuration]
[High-integrity earth ground required]
Applications
The MTL7755AC is specifically designed for floating RTD temperature measurement protection in hazardous area installations:
| Industry | Application |
|---|---|
| Oil & Gas | 2-wire and 3-wire Pt100 temperature measurement on offshore platforms and refineries |
| Chemical Processing | Reactor temperature monitoring with floating bridge RTDs in explosive atmospheres |
| Pharmaceutical | Sterile processing temperature measurement requiring Ex ia IIC certification |
| Power Generation | Turbine bearing temperature monitoring with 2- or 3-wire RTDs |
| Industrial Automation | Process temperature measurement in hazardous locations |
| Analyzer Systems | Used in ABB AK102 analyzer systems for temperature measurement |
Typical field devices connected:
- 2-wire Pt100, Pt500, Pt1000 RTD temperature sensors (floating bridge configuration)
- 3-wire Pt100, Pt500, Pt1000 RTD temperature sensors (floating bridge configuration)
- Floating bridge resistance sensors
- Temperature transmitters in hazardous areas
Installation Information
| Parameter | Detail |
|---|---|
| Mounting | Standard 35 mm T-section DIN rail (EN 60715) |
| Terminals | Removable screw terminals, colour-coded (blue for hazardous area) |
| Grounding | High-integrity earth connection made simultaneously when clipping onto DIN rail |
| Wire Entry | Angled to assist wiring in limited space enclosures |
| Terminal Capacity | Accommodates conductors up to 2.5 mm² |
| Clearance | Minimal — 12.6 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)
- Hazardous-area terminals are identified by blue labels
- For bussed power applications, use with MTL7798 power feed module
- Suitable for 2-wire or 3-wire floating bridge RTD configuration
- The barrier is a sealed unit — no repair is permitted; replace with same type if faulty
Ordering Information
| Item | Details |
|---|---|
| Part Number | MTL7755AC |
| Brand | Eaton (Crouse-Hinds series MTL) |
| Product Family | MTL7700 Range — Zener Barriers |
| Tariff Code | 85364900 |
| Weight | 0.106 kg - 0.200 kg |
| Country of Origin | India |
| Condition | New, Original, Factory Sealed |
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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