IS200VTURH2BAB: Primary Turbine Protection on the Mark VI VME Bus

The IS200VTURH2BAB is the H2B revision of GE's VTUR primary turbine protection card, a VME board that turns raw speed-pickup signals into the Mark VI's primary overspeed trip. It is among the most safety-critical cards in a Speedtronic lineup: alongside speed sensing and overspeed protection, it monitors induced shaft voltage and current and, on gas turbines, supervises the flame detectors. Like every VTUR, it interfaces with the TTUR terminal board that carries the field wiring and with the TRPx trip boards that act on the trip solenoids.

Speed inputs, overspeed trip, and shaft monitoring

VTUR accepts up to four passive magnetic speed pickups spanning roughly 2 Hz to 20,000 Hz and uses the median speed both for control and for the primary overspeed trip, with enough sensitivity to detect very low rotation for zero-speed and turning-gear logic. On a trip it drives three primary overspeed relays on the appropriate TRPx board (TRPG for gas, TRPS or TRPL for steam), which command the emergency trip devices. It also measures induced shaft voltage and current and alarms on excessive levels. In a TMR system a card sits in each of the <R>, <S>, and <T> control cores and the outputs are voted; a simplex system uses one card, while the <P> core's VPRO board provides separate emergency overspeed protection.

The symptom that looks like the H2B card but is not

Most VTUR complaints resolve to the sensors, cabling, or terminal boards rather than the card. Before fitting a replacement, work through these:

• Speed dropout or noise: inspect the magnetic pickup and gap, the field wiring to TTUR, and the JR5 speed cable. In TMR, a single faulty channel is voted out, so one bad reading rarely condemns the board.
• Spurious or missing overspeed trip: the trip chain includes the TRPx and TREx boards, the ETD (trip solenoid) wiring, and the trip power feed. Establish which element latched from the HMI before ordering.
• Flame-loss trips on gas turbines: a fouled Geiger-Mueller detector or a fault in its external supply through TRPG will imitate a card fault.
• Synchronizing or 52G breaker faults: the PT inputs and breaker relays reside on TTUR, so these usually are not VTUR problems.
• No communication with the controller: reseat the card and check backplane power and firmware revision first.

A methodical pass through the pickups, cables, terminal boards, and trip chain is the surest way to confirm the card really is the fault.

H2B versus H1B: what the revision code tells you

Read the number as IS200 (Mark VI IS200 series), VTUR (VME turbine primary-protection function), H2 (hardware group), B (functional revision), and AB (artwork and coating revision). The H1 and H2 builds are revisions of the same VTUR function; they are not arbitrary substitutes, because some systems are configured for a specific revision. Match the complete string on your installed card rather than mixing H1 and H2 without checking. Our GE Speedtronic Part Number Decoder explains the code segment by segment.

Terminal boards and backup protection that work with VTUR

The VTUR is one piece of a protection chain. Field wiring lands on the TTUR terminal board (linked through JR5 and JR1), trip commands flow through the TRPx/TREx boards, and the VPRO card supplies independent emergency overspeed protection. Review related boards in the GE Mark VI IS200 Boards collection and the broader GE Speedtronic Turbine Control Boards range. The card is documented in GE's Mark VI System Guide, GEH-6421, and our Mark V vs Mark VI: DS200 to IS200 guide shows how protection changed between generations.

Include this in your request

• Full part number and suffix as printed (IS200VTURH2BAB) and any additional revision markings
• A photo of the board label
• Turbine model and Mark VI generation
• Simplex or TMR, and the affected core if known
• Quantity and urgency

Request pricing and availability

This IS200VTURH2BAB is offered used, cleaned and tested, backed by the warranty shown below. Click Request a Quote and we reply within 24 hours. We ship worldwide DDP and accept purchase orders from qualified organizations. Because this is a protection card, include your turbine model and urgency so we can confirm the correct revision and lead time.