GE DS3800NGMA

Key Technical Parameters

Advantages and Distinctive Features

• Mechanical Relays with Tachometer Feedback: The DS3800NGMA uniquely combines 3A mechanical relay outputs with 2 tachometer input channels—allowing the CPU to verify fan operation while benefiting from relay isolation and high surge tolerance.

• AC/DC Output Capability: Can switch both AC and DC fan loads, providing flexibility for mixed cabinet installations.

• High Surge Current Handling: Mechanical relays handle 5A surges, making them suitable for fan motors with high startup currents.

• Complete Galvanic Isolation: Relay outputs provide 2500V isolation between control logic and fan power circuits.

• Full 8 Thermocouple Inputs: Comprehensive zone-by-zone temperature monitoring.

• Simple, CPU-Dependent Operation: No onboard setpoint storage—keeps the board cost-effective and easy to troubleshoot.

Typical Application Fields

• Turbine Cabinets with Mixed AC/DC Fans: Where both AC and DC fans are present and speed monitoring is required.

• Safety-Critical Cooling Systems: Applications where fan failure must be detected immediately.

• High-Inrush Fan Applications: Mechanical relays handle startup surges better than solid-state alternatives.

• Climate-Controlled Indoor Installations: 0°C to +60°C range supports standard power plant environments.

• Retrofit from NFEE Boards: Upgrading to the DS3800NGMA adds tachometer monitoring without changing the relay output type.

Comparison with Related Models

Selection Recommendations

• Choose the DS3800NGMA if:

  • Your fans require mechanical relay outputs (AC or DC) with high surge handling.

  • You need tachometer feedback to verify fan operation.

  • Your cabinet requires 8 temperature sensors for comprehensive monitoring.

  • You have a climate-controlled environment (0°C to +60°C).

  • The Mark V CPU handles all control logic.

  • You want a cost-effective hybrid solution without advanced firmware features.

• Choose the DS3800NFLA if: You need similar functionality but prefer the “NFLA” component revision (verify compatibility for your system).

• Choose the DS3800NFEE if: You need relay outputs but do not require tachometer feedback.

• Choose the DS3800NFIA if: You prefer solid-state DC outputs with tachometer feedback.

Critical Precautions

• ESD Protection: The DS3800NGMA contains sensitive ADC components. Always wear a grounded ESD wrist strap.

• Relay Contact Wear: Mechanical relays are rated for 100,000 operations at 3A. For frequent cycling applications, consider derating or using solid-state alternatives.

• Inductive Load Derating: The 3A rating applies to resistive loads. For inductive fan motors, derate to 2A or use an external RC snubber across each relay output.

• Tachometer Wiring: Use shielded twisted-pair cable for tachometer signals. Connect the shield to the DS3800NGMA‘s designated shield terminal. Keep tach wiring separate from fan power cables.

• No Hot-Swap: Always depower the Mark V rack before inserting or removing the DS3800NGMA.

• Slot Assignment: Install in auxiliary I/O slots (typically slots 8–10). Do not install in CPU or analog input slots.

• CPU Dependency: Since the DS3800NGMA has no onboard logic, the Mark V CPU must process tachometer feedback and send fan ON/OFF commands. If backplane communication is lost, the board defaults to 100% fan speed—tachometer monitoring will be disabled in fallback mode.

• Firmware Compatibility: The DS3800NGMA is compatible with all Mark V CPU firmware versions (v3.x and above). No specific CPU upgrade is needed for basic functionality.