Product Overview

The Weidmuller 8965440000 (ACT20X-2HAI-2SAO-S) is a sophisticated 2-channel HART-protocol transparent current-supply isolator designed for hazardous area applications. Part of the ACT20X series, this module provides signal isolation and conditioning for 4 to 20 mA loops while maintaining full transparency for bidirectional HART communication. Engineered for high-stakes environments such as chemical processing and offshore platforms, the 8965440000 effectively decouples field devices from the control system, eliminating ground loops and protecting sensitive DCS/PLC inputs from high-voltage transients. Its primary value lies in its high accuracy (< 0.1% Span) and integrated alarm functions, which proactively monitor for line interruptions and device errors to maximize process availability.

Technical Configuration

The ACT20X-2HAI-2SAO-S is a dual-channel powerhouse housed in a slim 22.5 mm enclosure, saving significant DIN-rail space. It operates on a wide supply voltage range of 19.2 to 31.2 VDC and is fully configurable via FDT/DTM software, allowing for precise adjustment of signal limits and alarm thresholds.

One of its standout features is "HART Transparency," which ensures that digital diagnostic data from smart transmitters can pass through the isolator without distortion. The module also features a dedicated relay alarm output for collective error messaging. It monitors for four distinct fault conditions: signal limit violations, input line interruptions, supply voltage loss, and internal device errors. The screw connection system provides high mechanical stability, ensuring reliable electrical contact even in high-vibration industrial settings.

Technical Specifications

Technical FAQs

Q1: What does "HART Transparent" mean for this isolator?

A1: It means the module does not strip away the high-frequency digital signal superimposed on the 4 to 20 mA analog loop. This allows your DCS or handheld communicator to "see" and configure smart field devices through the isolator.

Q2: How do the alarm functions improve plant safety?

A2: The module features a physical relay contact that opens or closes when a fault occurs (like a broken wire). This provides an immediate hardware-level notification to the safety system, independent of the analog signal value.

Q3: Can the ACT20X-2HAI-2SAO-S be installed directly in ATEX Zone 0?

A3: The module itself must be installed in a safe area or Zone 2, but it is designed to interface with intrinsic safety (IS) signals coming from Zone 0, 1, or 2. Always check the specific Ex-certification markings on the device housing.

Engineering & Installation Guide

• Software Configuration: Use the Weidmuller WI-Manager (FDT frame) and the specific DTM for ACT20X to set up the device. This allows you to define "Active" or "Passive" input modes and configure the fail-safe behavior of the relay output.

• Thermal Management: Although the module is rated up to 60 deg C, maintain a 5 mm gap between adjacent high-power modules if the ambient temperature in the cabinet consistently exceeds 45 deg C. This prevents the internal "Step response time" from drifting due to thermal stress.

• Wiring and Termination: For HART communication integrity, ensure that the total loop impedance (including the 250 Ohm resistor) does not exceed the module's driving capability. Use shielded twisted-pair cables for the 4 to 20 mA loops to maintain the < 0.1% accuracy in high EMI environments.

Engineering Advantages

The ACT20X-2HAI-2SAO-S is distinguished by its extremely low temperature coefficient (< 0.01% of span per deg C), ensuring that signal measurements remain precise regardless of seasonal temperature swings in the control room. Its rapid 5 ms response time makes it suitable for fast-acting control loops and safety-instrumented systems (SIS). Furthermore, the 2-channel design provides a 50% reduction in DIN-rail footprint compared to standard single-channel isolators, making it the ideal choice for high-density marshalling cabinets in modernized plant architectures.