GE DS3828BS3A

Parameters

Advantages & Features

• Integrated LVDT Feedback – The GE DS3828BS3A eliminates the need for separate analog input modules for valve position feedback, reducing rack space, wiring, and cost. Each channel independently excites the LVDT and conditions the return signal.

• Closed-Loop Ready – With output drive and feedback conditioning on one module, the GE DS3828BS3A allows the Mark VIe controller to implement true closed-loop valve positioning in firmware, achieving positioning accuracy better than ±0.5% of full stroke.

• Built-in Dither – Programmable dither (70–400Hz) reduces valve stiction and hysteresis, improving low-flow linearity by up to 50%.

• Comprehensive Diagnostics – Continuous monitoring detects output open-load, LVDT open-circuit, short-circuit, and coil degradation. All faults are reported to the controller within one scan cycle.

• Bi-directional Output – Supports ±20mA and ±50mA ranges, compatible with most torque-motor servo valves (Moog, Bosch, Rexroth).

• SIL 2 Capable – Suitable for safety-critical fuel and steam control loops with appropriate external voting and proof-testing.

Application Cases

• Gas Turbine Fuel Control – The GE DS3828BS3A drives the main fuel servo valve (Moog D633, ±40mA) and reads its LVDT feedback simultaneously, enabling closed-loop fuel flow control with <0.5% positioning error. A single module controls main, pilot, and liquid fuel valves with individual LVDT feedback.

• Steam Turbine Valve Positioning – In 500MW steam turbines, the GE DS3828BS3A positions HP/IP control valves using ±20mA drive and LVDT feedback, compensating for valve wear and thermal expansion over time.

• Hydro Turbine Gate Control – Controls distributor gate servo actuators with LVDT feedback, ensuring precise wicket gate positioning for optimized turbine efficiency.

• Aeroderivative Turbine Fuel Metering – In LM6000-type turbines, the GE DS3828BS3A drives fuel metering valves with dual LVDT feedback for redundant position verification, meeting SIL 2 requirements.

Competitor Comparison

The GE DS3828BS3A uniquely integrates drive and feedback in one slot, saving rack space and simplifying wiring. Competing solutions require separate input and output modules, increasing cabinet footprint and potential failure points.

Selection Suggestions

• Choose the GE DS3828BS3A when your servo valve provides LVDT/RVDT position feedback and you require closed-loop control within the Mark VIe controller. It is the most space-efficient solution for 3-valve systems (typical for gas turbines).

• If your valve has no position feedback (e.g., simple proportional solenoid), use the DS3828BH3A or DS3828BH3AH instead — the GE DS3828BS3A‘s feedback capability is unnecessary.

• Verify LVDT compatibility: primary impedance 100–500Ω, secondary impedance 200–1000Ω, sensitivity 5–50mV/V/mm. The GE DS3828BS3A supports most standard LVDT types but may require custom excitation settings for non-GE sensors.

• For SIL 2 applications, pair the GE DS3828BS3A with a redundant feedback channel (e.g., second LVDT on the same valve) connected to a separate analog input module.

• Order matching terminal block TB400-S-LVDT (with dedicated LVDT connector and screw-clamp outputs).

Precautions

• LVDT Wiring – Use twisted shielded cables for LVDT connections (3-wire or 5-wire). Connect the shield to the module’s COM terminal at the module end only to avoid ground loops. Separate LVDT cables from power cables by at least 10cm to prevent noise coupling.

• LVDT Excitation Matching – The GE DS3828BS3A provides programmable excitation (1–10kHz, 1–10Vrms). Incorrect frequency or amplitude can cause LVDT saturation or insufficient signal-to-noise ratio. Consult your LVDT datasheet before configuration.

• Output Short-Circuit – Current limited to 150mA but not foldback. Sustained shorts dissipate up to 3.6W per channel; do not operate with shorted outputs for >5 minutes.

• Grounding – Output common and LVDT common are internally connected. For valves with isolated inputs or dual LVDTs with separate commons, use external isolators.

• Dither and LVDT Interference – High dither amplitudes (>15%) can couple into LVDT feedback signals, causing position measurement ripple. Keep dither amplitude below 10% when closed-loop control is active, or use the module’s built-in 50/60Hz notch filter.

• Feedback Sampling Delay – The GE DS3828BS3A samples feedback at 500Hz (2ms per channel sequentially). For fast-acting valves requiring <1ms response, consider using separate high-speed AI modules instead.

• Power Supply Sizing – Total current = 450mA + load current. With all channels at ±50mA, total ≈ 600mA. Use a 24V supply rated ≥800mA per module.

• Calibration – Factory calibration covers both output and feedback channels. Valid for 24 months; recalibration requires both current source and LVDT simulator — field calibration is not recommended.

• Firmware Compatibility – Requires Mark VIe controller firmware v7.0 or higher for full LVDT configuration options