Description
The GE WESDAC D20 is a compact, intelligent Remote Terminal Unit (RTU) originally developed under the Westinghouse Energy Systems lineage and later integrated into GE’s automation portfolio. Designed for utility and industrial SCADA applications, the GE WESDAC D20 provides localized data acquisition, control logic execution, and secure communication over multiple protocols—including DNP3, Modbus RTU/TCP, and legacy WESDAC proprietary formats. Its ruggedized design and wide environmental tolerance make it ideal for deployment in substations, pump stations, and remote generation sites.
As a key component of the WESDAC SCADA architecture, the GE WESDAC D20 interfaces directly with field devices such as circuit breakers, reclosers, meters, and sensors via digital and analog I/O channels. It features dual serial ports (RS-232/485) and optional Ethernet connectivity, enabling flexible integration into both legacy serial networks and modern IP-based control systems. The GE WESDAC D20 supports time-synchronized event reporting (SOE) with millisecond resolution—critical for fault analysis in power distribution networks. Despite its age, thousands of GE WESDAC D20 units remain in active service worldwide due to their proven reliability and long lifecycle support.
GE WESDAC D20
Technical Specifications
| Parameter Name | Parameter Value |
| Product Model | WESDAC D20 |
| Manufacturer | GE (General Electric, legacy Westinghouse line) |
| Product Type | Remote Terminal Unit (RTU) / Intelligent I/O Processor |
| I/O Capacity | Up to 32 digital inputs, 16 digital outputs, 8 analog inputs (model-dependent) |
| Communication Interfaces | 2 × RS-232/485 serial ports; optional 10/100 Mbps Ethernet |
| Supported Protocols | DNP3 Level 2, Modbus RTU/TCP, WESDAC native protocol |
| Power Supply | 24 VDC or 125 VDC (isolated input, ±10% tolerance) |
| Operating Temperature | –25°C to +70°C (industrial grade) |
| Mounting | DIN rail (35 mm) or panel mount |
| Dimensions | Approx. 150 mm × 110 mm × 80 mm (W × H × D) |
| Real-Time Clock | Yes, with battery backup (supports SOE timestamping) |
| Environmental Rating | IP20 (indoor use); conformal coating available for humidity resistance |
Main Features and Advantages
Proven reliability in critical infrastructure:
The GE WESDAC D20 has operated continuously for decades in electric cooperatives, municipal water systems, and oil & gas pipelines. Its hardened firmware and robust power supply design withstand voltage sags, surges, and EMI—common in rural or industrial settings.
Multi-protocol interoperability:
Unlike single-protocol RTUs, the GE WESDAC D20 natively supports DNP3 for utility compliance, Modbus for third-party device integration, and legacy WESDAC commands for backward compatibility. This eliminates the need for external protocol gateways, reducing system complexity.
Sequence-of-Events (SOE) with millisecond accuracy:
Equipped with a battery-backed real-time clock, the GE WESDAC D20 timestamps digital input changes with ≤1 ms resolution—enabling precise fault location during outages. This feature is essential for NERC-compliant grid monitoring.
Flexible I/O expansion and local logic:
While compact, the GE WESDAC D20 can execute basic control logic (e.g., auto-reclose sequences, alarm annunciation) without master station intervention. Optional I/O modules allow scaling to match application needs—from a single capacitor bank to a full feeder monitor.
Seamless integration into hybrid SCADA systems:
Many utilities use the GE WESDAC D20 as a “bridge” device during phased SCADA modernization. It collects data from legacy electromechanical relays and transmits it via Ethernet to modern historian platforms—extending asset life while enabling digital transformation.
Application Field
The GE WESDAC D20 is predominantly deployed in electric power distribution, where it monitors and controls overhead feeders, underground networks, and substation auxiliaries. In rural electric cooperatives across North America, the GE WESDAC D20 manages recloser coordination and sectionalizing switches, reducing outage durations through automated isolation and restoration.
In water and wastewater treatment, the GE WESDAC D20 interfaces with level sensors, pump starters, and chlorine analyzers, transmitting real-time data to central control rooms via cellular or radio links. Its low power consumption allows solar-powered operation at remote reservoirs.
Renewable energy sites also utilize the GE WESDAC D20 for solar farm combiner box monitoring and wind turbine auxiliary control, where its wide DC voltage range accommodates fluctuating site power conditions. Even in decommissioned nuclear facilities, the GE WESDAC D20 supports long-term environmental monitoring due to its audit-ready event logging and minimal maintenance requirements. Across all these roles, the GE WESDAC D20 delivers unmatched longevity in harsh, unattended environments.
GE WESDAC D20
Related Products
- WESDAC D40: Enhanced RTU with more I/O capacity and dual Ethernet ports—direct successor toWESDAC D20
- WESDAC D10: Smaller, cost-reduced version with limited I/O—used for simple switch status monitoring
- GE MDS PulseNET: Modern wireless SCADA radios often paired withWESDAC D20 for remote sites
- SEL-3505: SEL RTU that can replaceWESDAC D20 in new installations requiring IEC 61850
- WESDAC Master Station Software: Legacy SCADA host platform designed to communicate withWESDAC D20
- GE Multilin S40: Protective relay that can share data withWESDAC D20 via Modbus for integrated protection & control
- WESDAC I/O Expansion Modules: Plug-in cards (e.g., DI16, AO4) to increase functionality ofWESDAC D20
- ABB RTU500: Contemporary alternative for utilities migrating from GE WESDAC platforms
