DS3800HITA | GE Turbine Overspeed Protection Module

Description

Product Introduction

The DS3800HITA is the dedicated speed input board for the Mark V—it’s designed specifically for magnetic speed sensors that measure turbine shaft speed and provide overspeed protection. This board is one of the most critical components in the Mark V system, as it directly supports turbine overspeed detection and tripping. The HITA accepts inputs from magnetic pickup sensors (typical 120V AC signals) and processes them for speed measurement and overspeed detection. The board includes a hardware watchdog timer that trips the turbine if speed exceeds a programmed threshold, providing a failsafe mechanism independent of the main controller.

We’ve used the HITA in multiple turbine installations where speed measurement is critical for safe operation. The board’s magnetic pickup compatibility allows direct connection to the speed sensors mounted on the turbine shaft. The overspeed detection circuit is hardware-based, ensuring that the turbine trips even if the main controller fails. The HITA is a reliable and robust speed input board that is essential for turbine protection.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: What’s the difference between the HITA and a standard frequency input board like the HFPB?
A: The HITA is a dedicated speed input board with hardware-based overspeed detection and a watchdog timer. The HFPB is a general-purpose frequency input board that measures frequency but does not have dedicated overspeed protection. The HITA is used for critical turbine speed measurement and overspeed protection, while the HFPB is for general frequency counting applications.

Q: What type of speed sensors does the HITA support?
A: The HITA supports magnetic pickup sensors that output a 120V AC signal. These are the most common speed sensors used on gas and steam turbines. The board’s input impedance (10kΩ) is compatible with most magnetic pickups. If you have different sensor types, you may need a signal conditioner.

Q: How does the overspeed detection work on the HITA?
A: The HITA has a hardware-based watchdog timer that monitors the speed signal. If the speed exceeds a programmed threshold, the board triggers a hardware trip signal that shuts down the turbine. This operates independently of the main controller, providing a failsafe mechanism. The trip threshold is programmed in the Mark V configuration.

Q: What’s the accuracy of the speed measurement on the HITA?
A: The HITA provides speed measurement with an accuracy of ±0.1% of the setpoint. This is sufficient for turbine control and overspeed protection. The board uses a high-precision frequency measurement circuit to ensure accurate speed readings.

Q: Does the HITA have conformal coating?
A: Not by default. The HITA’s suffix typically indicates termination type, not coating. If you need conformal coating for harsh environments, look for a suffix with a “G” (e.g., DS3800HITA1G1G). The standard HITA is suitable for indoor environments. If your plant has high humidity or corrosive conditions, consider a coated variant.

Q: Can I use the HITA for speed measurement on a steam turbine?
A: Yes, the HITA is suitable for both gas and steam turbines. The speed measurement and overspeed detection functions are the same regardless of the turbine type. The board’s input range covers the typical speed range of both gas and steam turbines.

Q: What’s the backplane current draw of the HITA?
A: The HITA draws 1.0A from the 5V backplane rail. The Mark V power supply is rated at 6A on the 5V rail, so the HITA is within the limit. If your rack has multiple HITA boards, check your total backplane current. We recommend keeping total backplane current below 5.5A for margin.

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