DS3800DXRC1D1B GE

Technical Specifications

• Product Type: Digital Expansion Relay & Alarm Board (Revision C1D1B)

• Part Number: DS3800DXRC1D1B

• Manufacturer: General Electric (GE)

• System Compatibility: GE Speedtronic Mark IV Turbine Control Systems

• Output Channels: 16 digital outputs (Form C – SPDT relays)

• Relay Type: Magnetic latching relays (maintain state after power loss)

• Contact Rating: 5A @ 250VAC or 5A @ 30VDC (resistive); 3A @ 250VAC (inductive)

• Surge Suppression: Enhanced RC snubbers + bidirectional TVS diodes

• Indicators: Front-panel LEDs per channel + mechanical flag indicators (latching)

• Isolation: 2500Vrms reinforced opto-isolation

• Expansion Interface: Backplane slave connection; address configurable via DIP switches

• Diagnostics: Individual channel fault detection and status reporting via backplane

• Temperature Range: -40°C to +70°C

• MTBF: > 200,000 hours (MIL-HDBK-217F)

Key Features & Advantages

• Latching Relays with Flags: The GE DS3800DXRC1D1B is the only expansion relay board with magnetic latching relays and mechanical flags, combining the functionality of both DS3800DXRA (expansion) and DS3800DRFA (flags) into a single board.

• State Retention: Magnetic latching relays maintain their state after power loss, critical for trip circuits that require visual and electrical memory of alarm conditions.

• Mechanical Flag Indicators: Provide instant visual confirmation of relay status without tools or software.

• Enhanced Diagnostics: Individual channel fault detection reported via backplane to the Mark IV processor.

• Reinforced Isolation: 2500Vrms for ground loop and transient protection.

• Flexible Addressing: DIP switch configuration for easy address assignment.

• Diagnostic LEDs: Front-panel LEDs indicate output status, fault, and flag state.

Typical Application Cases

• Critical Trip Circuits: The GE DS3800DXRC1D1B provides latching outputs for emergency shutdown valves, maintaining trip state after power loss with mechanical flag indication.

• Alarm Annunciation with Memory: Provides alarms that remain visually indicated even after power cycles, aiding post-trip fault analysis.

• Expanded Latching Outputs: Adds latching relay capacity beyond the base DS3800DRFA boards.

• Remote Signaling with Latching: Sends latched status signals to plant DCS, maintaining state during communication interruptions.

• Retrofit Projects: Replaces combination of separate expansion and flag boards, saving rack space.

Competitive Comparison

The GE DS3800DXRC1D1B uniquely combines latching relays, mechanical flags, and expansion capability in a single board, offering the most functionality in the expansion relay family.

Selection Guidelines & Precautions

1. Latching Relay Reset: After a trip, latching relays must be reset via a command from the Mark IV processor or manual reset button. The GE DS3800DXRC1D1B will retain its state until reset, preventing turbine restart if not cleared.

2. Processor Compatibility: Verify Mark IV firmware supports diagnostic reporting from expansion boards. Earlier firmware may ignore fault data.

3. Flag Maintenance: Mechanical flags can stick after prolonged idle periods. Cycle each channel during commissioning to ensure free movement.

4. Address Configuration: Set DIP switches correctly to avoid backplane address conflicts.

5. Contact Current: Do not exceed 5A resistive or 3A inductive. Use external interposing relays for larger loads.

6. Wiring: Use shielded cables; ground shield at board end only.

7. ESD Handling: Use ESD-safe practices.

8. Sourcing: Obsolete. Request functional test report including:

   • All 16 channels tested under rated load (resistive and inductive)

   • Latching functionality verified (state retention after power cycle)

   • Mechanical flag operation verified

   • Diagnostic reporting validated via backplane

   • Contact resistance (< 0.1Ω new, < 0.5Ω refurbished)

   • Surge suppression verification

   • Isolation test (2500Vrms)

9. Spare Strategy: Keep one spare GE DS3800DXRC1D1B on-site, especially for critical trip circuits. Consider this board the preferred replacement when both expansion and latching/flag functionality are required.