Before You Order an IS200TTURH1BED, Make Sure It's the Culprit

Turbine speed alarms, failed synchronizing attempts, and shaft voltage warnings all get traced back to this terminal board more often than they should be. The IS200TTURH1BED is GE's Turbine Termination board for the Mark VI Speedtronic system, and its actual job is narrower than the alarm list suggests: it's the physical termination point for magnetic speed pickups, potential transformer voltage signals, and shaft voltage/current sensors, and it drives the generator breaker coil (52G) at a nominal 125 V DC once synchronizing conditions are met. The control logic behind all of this runs on a separate VME card, VTUR, in the R/S/T Control Module — the TTUR only reaches it by cable, through six connectors labeled JR1/JR5, JS1/JS5, and JT1/JT5.

Field wiring lands on two 24-terminal blocks, TB1 and TB2 (rated up to #12 AWG), with a shield ground strip beside each, and jumpers JP1/JP2 set the board for simplex or TMR relay-drive operation. Closing the generator breaker requires three permissive relays — K25, K25P, and K25A — to all be satisfied, backed up by an external synch check relay and breaker-side feedback through a 52G/a auxiliary contact.

The Diagnostic Checklist

Work through this before assuming the board itself needs replacing:

• Won't synchronize / breaker won't close: check PT wiring and fuses, the external synch check relay, the 52G/a feedback contact, and confirm JP1/JP2 match your simplex or TMR configuration.
• Erratic speed or nuisance overspeed: check the magnetic pickup's air gap and its cable run to TB1/TB2 first — this is a far more common cause than a bad board, and on TMR systems shows up as a voting disagreement rather than a clean fault.
• Shaft voltage/current alarm: this almost always means a grounding brush or bearing insulation problem on the physical shaft, since the TTUR (with VTUR) only monitors that condition rather than causing it. Use the board's built-in DC and AC test circuits to confirm wiring continuity before assuming a hardware fault.
• Intermittent or unexplained faults: check for loose terminals on TB1/TB2 and confirm the JR/JS/JT cable connectors are fully seated.

If the fault holds up after all of the above, replacing the terminal board is the right call.

Reading the IS200TTURH1BED Part Number

IS200 is the platform prefix, TTUR the function code, and H1BED the group and revision — H1B for the group/generation, ED for this specific revision. Match the complete string when sourcing a replacement; H1B and H1C (both stocked in this collection) are separate hardware generations of the same basic board. Our GE Speedtronic Part Number Decoder explains how to read a full IS200 string.

Related Boards

The TTUR pairs with the VTUR VME card in the Control Module. The generator breaker trip circuit also runs through the TRPG terminal board (driven by VTUR) and, in the Backup Protection Module, the TREG terminal board (driven by VPRO). For older equipment, see our Mark V vs Mark VI: DS200 to IS200 guide and GE Mark V DS200 Boards Explained article. Browse the rest of the family in our GE Mark VI IS200 Boards collection or the wider GE Speedtronic Turbine Control Boards collection.

What to Include in Your Quote Request

• Full part number with suffix: IS200TTURH1BED
• Revision from the label
• Photo of the ID label
• Turbine/generator model and unit ID
• Planned outage or urgent need
• Quantity

Request a Quote

This IS200TTURH1BED is listed in used condition, cleaned and tested, with a 1-year warranty (see table below). We quote every order directly rather than publishing prices — submit a Request a Quote and expect a reply within 24 hours. We ship worldwide DDP, accept purchase orders, and support both planned outages and urgent breakdown needs.

General Information about the Product
Part Number	IS200TTURH1B Mark VI IS200
Description	IS200TTURH1B By GE IS200TTURH1BED Turbine Termination Board MK VI IS200
Condition	used Cleaned and Tested. With 1 Year Warranty.