Product Overview

GE Vernova D20 Series – WESDAC / WESTERM Distributed I/O Module
This module is a core signal acquisition and control unit in the GE Vernova D20 automation and protection system. It provides flexible digital and analog I/O, safety-critical relay outputs, and high-reliability communication for power, process, and industrial control applications.

Processing & Memory

Processor: Freescale 68HC11 8-bit MPU

Clock frequency: 2 MHz

Memory:

32 KB static RAM

512 B EEPROM

Digital Input

Channels: 16 discrete inputs

Input type: Dry contact / Wet contact

Response time: ≤ 1 ms

Control & Relay Outputs

Relay outputs:

8 × universal control relays

2 × Master Trip / Loss main relays

Contact rating: 600 VAC / 10 A

Action duration: Programmable from 1 ms to 2¹⁵ s

Designed to meet emergency trip and close control requirements in power systems

Analog Input (Optional Daughter Card)

Channels: 16 differential bipolar inputs

Resolution: 14-bit + sign

Accuracy:

±0.05% (voltage)

±0.1% (current)

Conversion rate:

275 ms (16 channels @ 60 Hz)

Analog Output (Optional)

Channels: 8

Type: Unipolar / Bipolar

Resolution: 12-bit

Output ranges:

±10 V

0–20 mA

Communication Interfaces

D.20 Link:

2 × DB9 interfaces

Supports daisy-chain cascading of multiple modules

Maintenance port:

1 × RS-232

Baud rate: 9600 bps

Power Supply

Input voltage: 20–60 VDC

Typical power consumption: 5 W

Maximum power consumption: 11 W

Mechanical & Environmental Specifications

Form factor: Standard 6U

Weight: Approx. 2.6 kg

Operating temperature:

Commercial: 0 °C to +60 °C

Wide temperature option: −40 °C to +85 °C

Protection:

Optional three-proof conformal coating (–CC suffix)

Core Strengths
Modular Design

WESTERM handles field wiring

WESDAC performs signal processing

Modular architecture simplifies maintenance, replacement, and system expansion, especially in complex wiring environments

Flexible I/O Configuration

Digital and analog I/O functions are customizable via plug-in daughter cards

Easily adapts to diverse signal acquisition and control requirements

High-Reliability Communication

D.20 Link supports multi-module cascading

RS-232 maintenance interface enables rapid diagnostics

Designed for environments with strong electromagnetic interference

Safety Control Capability

Master Trip / Loss relays support critical protection and emergency control

Programmable relay timing aligns with complex protection and interlocking logic

Compatibility & Expansion

Fully compatible with D20 series main processors

Supports expansion with:

WESMAINT maintenance module

D20KI intermediate relay module

Enhances overall system integration and scalability

Typical Application Scenarios
Power Systems

Substation relay protection and generator excitation control

Switch status acquisition and trip/close command output

Petrochemical Industry

Field I/O interface for DCS systems

Acquisition of pressure, temperature, and other analog signals

Control of valves, pumps, and actuators

Industrial Automation

Equipment status monitoring and logic control for production lines

Suitable for long-term stable operation in harsh industrial environments

GE WESDAC D20 C｜Analog Digital I/O Module｜