GE WESDAC D20C D20 RTU Combination I/O Board 68HC11

GE WESDAC D20C D20 Substation Automation I/O Board

The GE WESDAC D20C, also cataloged as the WESDAC D20C Analog Digital I/O Module, operates as a dedicated hardware component for distributed signal acquisition and local logic execution within GE D20 and D200 Remote Terminal Unit (RTU) platforms. The module consists of a WESTERM D20C field termination board and a WESDAC D20C processing board powered by an 8-bit Freescale 68HC11 MPU. Utilizing dual D.20 Link ports, the unit offloads signal conditioning, noise filtering, and trip/close control execution from the primary D20 CPU.

Hardware Specifications

Backplane Bus Communication Velocity and System Determinism

The GE WESDAC D20C module interfaces directly with the GE D20 backplane architecture to ensure rapid data exchange across distributed sub-networks. By executing input scanning and filtering locally, the card manages I/O density scaling efficiently while reducing protocol conversion latencies over the dual D.20 Link ports. Onboard firmware flash compatibility across D20 processor nodes maintains deterministic communications during high-volume event logging and protective tripping operations.

Frequently Asked Questions

Q: How does the two-component design simplify module replacement during live operations?

A: The detachable WESTERM D20C termination board remains permanently connected to the cabinet field wiring, allowing engineers to hot-swap the primary WESDAC D20C processing board without disturbing physical terminal blocks or risk rewiring errors.

Q: What power supply range does the module require, and how is the backplane isolated?

A: The module accepts a wide input power supply range from 20 to 60 VDC and features 1500 VAC galvanic isolation between field-side signal lines and the internal D20 backplane logic circuits.

Q: How do the dual D.20 Link communication ports handle network fault recovery?

A: The dual D.20 Link ports support redundant cabling topologies, enabling immediate, deterministic packet re-routing over the secondary link if a primary communication cable experiences an open circuit or signal degradation.

Field Installation Guidelines

Observe the following field installation practices during cabinet integration and commissioning:

1. Power Isolation & Verification: Verify that input DC power to the rack chassis is within 20 to 60 VDC before seating the card into the 3U sub-rack enclosure.
2. Termination Board Mounting: Secure the WESTERM D20C termination base to the mounting frame first, ensuring firm earth ground bonding to maintain 1500 VAC field-to-backplane isolation integrity.
3. ESD & Module Alignment: Wear a grounded ESD wrist strap, align the processing card with the chassis card guides, and push evenly until the edge connectors engage the backplane. Tighten retaining thumbscrews.
4. Signal Wiring & Shield Grounding: Strip field conductors to recommended lengths, securing 12 to 130 VDC discrete input and 4-20 mA analog wiring to screw terminals. Terminate all cable shields to the main cabinet ground bus.
5. Thermal & Clearance Spacing: Maintain a minimum 50 mm clearance above and below the 3U rack assembly to allow unhindered vertical convection, ensuring ambient air remains within the -40 to +70 deg C operating window.