IS200VTURH2BAC Replacement | GE Mark VI PCB

Description

Product Introduction

The GE IS200VTURH2BAC is a turbine protection board inside the Mark VI rack, responsible for monitoring critical parameters like vibration and voltage. On a gas or steam turbine, if you see thrust bearing wear or overspeed conditions, this is the card feeding that data to the protection system.

It’s part of the “VTUR” family—Voltage/Turbine monitor. The board conditions raw signals from proximity probes and voltage transformers, then passes them to the main control module for voting and trip decisions. We’ve pulled these from combined-cycle plants where a single faulty channel meant the difference between a scheduled outage and a forced trip.

 Key Technical Specifications

Compatible Replacement Models

The IS200VTURH2BAC is specific to the Mark VI turbine control platform. When sourcing replacements, pay attention to the hardware revision and the application:

• ✅ Drop-in Replacement: IS200VTURH2BAB, IS200VTURH2BAD. These are functionally identical boards with the same hardware revision. The last letter indicates factory calibration or component sourcing changes. They will swap directly without configuration changes, provided the turbine software expects the same signal scaling.
• ⚠️ Software Compatible: IS200VTURH1BAC. This is an older hardware revision (H1 vs H2). It will physically fit and communicate, but the signal conditioning circuitry may have different filter characteristics. Installing an H1 where an H2 is spec’d can cause phase shift in vibration signals, leading to incorrect trip decisions. We advise matching the H2 revision.
• ❌ Hardware Incompatible: IS200VIBH2BAC. The “VIBH” series is specifically for vibration monitoring only, lacking the voltage input stages. Putting a VIBH board in a slot configured for VTUR will result in missing channels and likely a turbine trip on “signal loss.”

 Frequently Asked Questions (FAQ)

Q: What does “VTUR” stand for in the part number?
Voltage/Turbine. It’s a combination monitor board that handles both voltage inputs (from potential transformers for electrical protection) and turbine mechanical inputs (vibration, thrust, case expansion). GE combined these functions to save rack space, but it means a failure affects multiple protection paths.

Q: Can I replace this board while the turbine is online?
We don’t recommend it. The VTUR board monitors live protection channels. If you pull it, those signals go to zero, and the turbine control logic may interpret that as a loss of signal and trip. Some sites have bypass switches for maintenance, but unless you’re certain the signals are bypassed in software, schedule this for a shutdown.

Q: My turbine is showing “Vibration Channel Failed” on startup. Is the board bad?
Start with the sensors. The IS200VTURH2BAC conditions signals from proximity probes (like Bently Nevada 3300 series). If a probe is damaged, the cable is cut, or the extension cable is wet, the board reports a fault. Disconnect the field wiring at the rack and measure the probe gap voltage with a multimeter. If the probe signal is good at the rack but the board reports failure, the input stage on that channel is likely damaged.

Q: How do I verify the board’s configuration after replacement?
You’ll need GE’s Toolbox software. Connect to the Mark VI controller, navigate to the I/O configuration screen, and read the board’s details. Verify the “Type” matches VTUR and the revision is recognized. Then, check live signal values against known good readings from before the swap. If vibration readings differ by more than 5%, the board may need calibration.

Q: What causes these boards to fail?
In our experience: power supply spikes and sensor faults. The Mark VI rack runs on +5V and +24V. If the power supply module drifts or fails, it can take out multiple boards. Also, shorted proximity probes—if a probe cable gets pinched and shorts to ground, it sends a surge back into the board’s oscillator circuit. Always check probe resistance before installing a new board.

Q: What’s the difference between IS200VTURH2BAC and IS200VTURH2BAB?
The hardware is identical. The last letter (“C” vs “B”) typically indicates a component change—for example, a different manufacturer’s op-amp or capacitor, or a calibration shift at the factory. GE used these suffixes to track Bill of Material changes. Functionally, they’re interchangeable. If you have a “C” and replace it with a “B,” verify signal scaling in Toolbox after installation.

Q: Does this board require calibration?
Yes, if you’re replacing it and expect SIL-rated accuracy. The VTUR board has potentiometers for adjusting gain and offset on each channel. A new board comes with factory calibration, but if your turbine’s sensors have specific scaling requirements, you may need a field technician with a signal generator to verify and adjust the board to match your system. Budget 2-4 hours for a full calibration check.

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