MTL SD32 Surge Protection Device with 20kA Surge Capacity Ultra-Slim 7mm Design and Integrated Fuse/Disconnect for Process Control
The MTL SD32 is a high-performance surge protection device (SPD) from Eaton's Crouse-Hinds MTL SD Series, specifically engineered for protecting 2-wire 4-20mA loops, digital outputs, alarms, LEDs, and solenoid valves in industrial process control systems. This ultra-slim DIN rail mount module uniquely combines hybrid surge protection with an integrated fuse/disconnect facility, providing both transient overvoltage protection and convenient circuit isolation in a single 7mm-wide unit.
The SD32 is part of the industry-leading MTL SD Series—a comprehensive range of surge protection devices offering unparalleled packing densities, application versatility, proven reliable hybrid circuitry, and simple installation. These features establish the series as the ultimate surge protection solution for process equipment, I/O systems, and communications networks.
The SD32 distinguishes itself by incorporating a fuse/disconnect package that provides fused protection against fault currents and a convenient method of isolating field circuitry without needing additional disconnect terminals. Includes a third connection for safe screen termination to earth.
With an exceptionally slim 7mm width, the SD32 allows for high packing densities on DIN rails. Individual modules can "double-up" as feed-through terminals, maximizing cabinet space utilization and reducing overall panel footprint.
Employs advanced multistage hybrid technology combining high-energy gas discharge tubes, varistors, and transient voltage suppression diodes. Delivers characteristically low let-through voltages while maintaining high surge current handling capability of 20kA maximum surge current.
ATEX and IECEx certified for use in potentially explosive atmospheres, making it suitable for gas and dust hazardous area installations in oil & gas, chemical, pharmaceutical, and mining facilities.
| Parameter | Value |
|---|---|
| Model | SD32 |
| Manufacturer | Eaton MTL (Crouse-Hinds series) |
| Series | SD Series |
| Nominal Voltage (DC) | 32 V |
| Nominal Voltage (AC) | 22 V |
| Nominal Current (In) | 250 mA |
| Maximum Surge Current (8/20 µs) | 20 kA |
| Nominal Discharge Surge Current (Isn) | 3 kA (8/20µs) |
| Response Time | <1 ns |
| Series Resistance | 4.2 Ω/line |
| Maximum Leakage Current | 5 µA |
| Maximum Continuous Operating Voltage (MCOV/Uc) | 36 V |
| Voltage Protection Level (Up) @1kV/ µs | <45 V |
| Residual Voltage @Isn | 60 V |
| Bandwidth (fG) | 25 kHz |
| Number of Terminals | 3 terminals (field + safe side with screen connection) |
| Mounting Type | DIN rail (35mm top-hat rail) |
| Dimensions (W x H x D) | 7mm x 101.3mm x 99mm |
| Operating Temperature | -40°C to +80°C |
| Protection Type | Full hybrid line-to-line; each line to screen/ground |
| Warranty | 10-year limited warranty |
| Country of Origin | India |
| Certification | Status | Details |
|---|---|---|
| ATEX | Certified | Intrinsically safe surge protectors |
| IECEx | Certified | Hazardous area certification |
| UL | Certified | UL E220693 |
| SIL 3 | Compliant | Suitable for safety instrumented systems |
| CSA | Certified | For North American installations |
| CCC | Certified | China Compulsory Certification |
| KOSHA | Certified | Korea certification |
| EAC | Certified | Eurasian Conformity |
| RoHS | Compliant | Restriction of Hazardous Substances |
| Application Area | Specific Use Cases |
|---|---|
| Process Control | 2-wire 4-20mA transmitters (pressure, temperature, flow, level) |
| Discrete I/O | Digital (on/off) outputs, alarms, LEDs |
| Actuator Control | Solenoid valves |
| Safety Systems | Emergency shutdown (ESD) systems |
| Fire & Gas Detection | Fire detectors, gas detectors |
| Shut-Down Systems | Critical process safety loops |
| Hazardous Areas | Oil & gas, chemical, pharmaceutical, mining facilities |
The SD32 is particularly well-suited for applications requiring both surge protection and circuit isolation capabilities in a single compact unit.
| Model | Terminals | Current Rating | Resistance | Key Feature | Application |
|---|---|---|---|---|---|
| SD32 | 3 | 250 mA | 4.2 Ω | Fuse disconnect + screen connection | Process I/O needing isolation |
| SD32X | 2 | 400 mA | 2.2Ω | Low resistance | 4-20mA loops (no isolation needed) |
| SD32R | 2 | 400 mA | - | High bandwidth | High speed data links, RS485 |
| SD32T3 | 3 | 400 mA | 2.2Ω | 3-wire protection | 3-wire transmitters, vibration sensors |
| SDRTD | 3 | 400 mA | - | RTD optimized | PT100/RTD temperature sensors |
| SD150X | 2 | - | - | High current | 110-240V AC power supplies |
Mounting Instructions:
- Snap the SD32 onto standard 35mm top-hat DIN rail until it clicks securely into place
- Ensure proper grounding through the DIN rail (automatic when mounted on grounded rail)
- The ultra-slim 7mm footprint allows high-density side-by-side mounting
Wiring Instructions:
The SD32 features three terminals on both field and safe sides:
- Terminal 1: Loop positive (+) from field side
- Terminal 2: Loop negative (-) from field side
- Terminal 3: Screen/shield termination to earth
Important Notes:
- The device connects in series with the protected circuit
- Series resistance of 4.2Ω is added to the loop
- The third terminal provides safe screen termination without additional components
- Use the disconnect feature for maintenance without rewiring
- Follow local electrical codes for proper installation
- Eaton MTL Reliability - Globally recognized leader in intrinsic safety and surge protection for industrial process control
- Most Compact Fuse-Disconnect Protector - At just 7mm wide, offers the highest packing density on the market
- Hazardous Area Approved - ATEX and IECEx certification allows installation in Zone 2 hazardous areas
- All-in-One Solution - Eliminates need for separate disconnect terminals and screen termination components
- 10-Year Warranty - Backed by Eaton MTL's industry-leading long-term reliability assurance
- Backward Compatible - Part of the SD Series platform for easy integration with existing installations
| Product | Part Number | Availability |
|---|---|---|
| MTL SD32 Surge Protector | SD32 | In stock - authorized distributors |
Alternate Part Numbers: SD32MXX-BCN (RS Stock No.: 144-8697)
Supplier Standard Pack: 15 units
Lead Time: Please contact local authorized Eaton MTL distributors for current availability
Warranty: 10-year manufacturer's warranty
The MTL SD32 Surge Protector delivers reliable, high-performance protection for 2-wire 4-20mA loops and discrete I/O circuits in industrial process control systems. With its 20kA surge capacity, <1ns response time, integrated fuse/disconnect facility, ultra-slim 7mm footprint, and hazardous area certifications, the SD32 is the ideal choice for engineers seeking to protect critical instrumentation while maintaining convenient circuit isolation capabilities.
Key advantages at a glance:
- Integrated fuse/disconnect - No need for separate disconnect terminals
- Screen termination - Third terminal for safe shield grounding
- 20kA surge capacity - Handles severe transient events
- <1ns response time - Instantaneous protection
- Ultra-slim design - 7mm width for high packing density
- ATEX & IECEx certified - Suitable for hazardous areas
- SIL 3 compliant - For safety instrumented systems
- Simple DIN rail mounting - Quick and secure installation
- 10-year warranty - Long-term reliability assurance
- 25kHz bandwidth - Suitable for standard process signals
Protect your process I/O with MTL SD32 - the all-in-one surge protection and isolation solution for harsh and hazardous environments.
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.