Eaton MTL SD32T3 3-Wire Surge Protection Device with Ultra-Slim Design for

The MTL SD32T3 is a high-performance three-terminal surge protection device from Eaton's Crouse-Hinds MTL SD Series, specifically engineered for 3-wire transmitters and sensors requiring separate power supply and signal lines. This compact module provides comprehensive hybrid surge protection for all three wires simultaneously, making it the ideal solution for protecting sensitive instrumentation in hazardous and harsh industrial environments.

Unlike standard 2-wire protectors, the SD32T3 offers complete protection for three-wire process transmitters such as pressure sensors, temperature probes, and other low-power industrial devices where the power supply and signal share separate conductors.

• Complete 3-Wire Protection in a Single Unit: Provides full hybrid surge protection for all three wires of a 3-wire transmitter or sensor in one ultra-compact module, eliminating the need for multiple protection devices.
• Ultra-Slim Space-Saving Design: With an exceptionally slim 7mm footprint, allows for high packing densities on DIN rails and can "double-up" as feed-through terminals.
• Proven Hybrid Protection Circuitry: Employs advanced multistage hybrid technology combining gas discharge tubes, varistors, and transient voltage suppression diodes for low let-through voltages and high surge current handling.
• No Loop Resistance Added for Signal Lines: Adds no series resistance for 4-20mA signal lines, ensuring no degradation of measurement accuracy.
• Hazardous Area Certified: ATEX and IECEx certified for use in potentially explosive atmospheres.
• Simple DIN Rail Installation: Snap-on mounting to standard 35mm top-hat DIN rail with automatic grounding via the DIN rail clip.

The MTL SD32T3 is specifically designed for protecting three-wire transmitters and sensors in the following applications:

The SD32T3 provides surge protection for all three wires of a 3-wire transmitter configuration:

• Wire 1 (Power +): Protects the positive power supply line
• Wire 2 (Power - / Common): Protects the return/ground reference
• Wire 3 (Signal): Protects the 4-20mA signal output

The hybrid protection circuit diverts surge currents safely to ground while clamping output voltages to safe levels. With a response time of < 1 nanosecond, the device reacts instantly to transient events, preventing damage to sensitive transmitter electronics before they occur.

The MTL SD Series includes multiple variants for different applications. Choose the correct model for your specific needs:

The SD32T3 is the recommended choice for protecting 3-wire pressure transducers and separately powered 4-20mA loops.

Mounting Instructions

1. Snap the SD32T3 onto standard 35mm top-hat DIN rail until it clicks securely into place
2. Ensure proper grounding through the DIN rail (automatic when mounted on grounded rail)
3. For wall or panel mounting, use optional mounting adapters

Wiring Instructions

Connect the three wires to the three terminals:

• Terminal 1: Power supply positive (+) from field side
• Terminal 2: Power supply negative/return (-) / common
• Terminal 3: 4-20mA signal output

Important Notes

• The device connects in series with the protected circuit
• Series resistance of 2.2Ω is added only on power lines (does not affect 4-20mA signal accuracy)
• Ensure all three wires are connected for complete protection
• Follow local electrical codes for proper installation

• Eaton MTL Reliability: MTL is a globally recognized leader in intrinsic safety and surge protection for industrial process control.
• Most Compact 3-Wire Protector on the Market: With its ultra-slim 7mm footprint, offers the highest packing density available.
• Hazardous Area Approved: ATEX and IECEx certification allows installation in Zone 2 hazardous areas without additional enclosures.
• 10-Year Warranty: Backed by Eaton MTL's industry-leading 10-year product warranty for long-term reliability.
• Backward Compatible: Compatible with the SD Series, allowing easy upgrades without rewiring existing installations.

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 SD32T3 Surge Protector delivers reliable, high-performance protection for 3-wire transmitters and separately powered 4-20mA loops. With its 5kA surge capacity, < 1ns response time, ultra-slim 7mm footprint, and hazardous area certifications, the SD32T3 is the ideal choice for engineers seeking to protect critical three-wire instrumentation from costly surge damage.

• Complete 3-wire protection - All three wires protected in one compact unit
• Zero signal line resistance - No impact on 4-20mA measurement accuracy
• 5kA 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

Protect your 3-wire transmitters with MTL SD32T3 - engineered for reliability in harsh and hazardous environments.