DS3800DXRA1A1A GE

Technical Specifications

• Product Type: Digital Expansion Relay & Alarm Board (Revision 1A1A)

• Part Number: DS3800DXRA1A1A

• Manufacturer: General Electric (GE)

• System Compatibility: GE Speedtronic Mark IV Turbine Control Systems

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

• Contact Rating: 5A @ 250VAC or 5A @ 30VDC (resistive); 2A @ 250VAC (inductive)

• Surge Suppression: Built-in RC snubbers and flyback diodes per channel

• Indicators: Front-panel LEDs per channel

• Isolation: 1500Vrms opto-isolation between logic and field contacts

• Expansion Interface: Backplane slave connection; fixed address via jumpers

• Temperature Range: 0°C to +60°C

• MTBF: > 150,000 hours (MIL-HDBK-217F)

Key Features & Advantages

• Slave Expansion: The GE DS3800DXRA1A1A adds 16 relay outputs without occupying a processor slot, receiving commands via the backplane.

• Form C Contacts: Each channel provides both NO and NC contacts for flexible configuration.

• Built-In Surge Suppression: Protects contacts and logic from inductive load spikes.

• Diagnostic LEDs: Front-panel LEDs indicate output status per channel.

• Fixed Address: Simple jumper configuration for board addressing.

• Proven Reliability: Initial revision with long field track record.

Typical Application Cases

• Alarm Annunciation Expansion: Adds extra alarm channels for detailed turbine status reporting.

• Additional Control Outputs: Provides extra outputs for auxiliary equipment (fans, heaters, lighting).

• Remote Signaling: Sends additional status signals to plant DCS or SCADA.

• Interlock Logic: Extra relay contacts for safety interlocks and permissives.

• Retrofit Projects: Expands I/O capacity in older Mark IV systems.

Competitive Comparison

The GE DS3800DXRA1A1A is functionally identical to the base DS3800DXRA and provides cost-effective I/O expansion for Mark IV systems.

Selection Guidelines & Precautions

1. Channel Count: Confirm required additional outputs. Multiple DS3800DXRA1A1A boards can be installed.

2. Processor Compatibility: Verify Mark IV processor supports expansion boards (most standard configurations do).

3. Address Configuration: Set jumpers correctly to avoid backplane address conflicts. Refer to Mark IV manual.

4. Contact Current: Confirm load does not exceed 5A resistive or 2A inductive. Use external interposing relays for larger loads.

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

6. ESD Handling: Use ESD-safe practices.

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

   • All 16 channels tested under rated load

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

   • Surge suppression verification

   • Address configuration validation

8. Spare Strategy: Keep one spare GE DS3800DXRA1A1A on-site if additional relay outputs are critical.