IS200TTURH1BCC and Shaft Voltage Monitoring

One function of the IS200TTURH1BCC that's easy to overlook is shaft voltage and shaft current monitoring — a protective circuit that has nothing to do with speed or synchronizing and everything to do with bearing health. As a rotor spins, induced shaft voltage can build up until it discharges through the oil film in a bearing; repeated discharge and arcing pits and roughens the bearing surface, eventually causing accelerated mechanical wear and failure. Working together with the VTUR VME card in the Control Module, this terminal board continuously monitors shaft-to-ground voltage and current and can alarm at excessive levels, with built-in test circuits to check both the alarm function and the continuity of the external wiring.

That's on top of the TTUR's other core job: turbine speed sensing and generator synchronizing. Passive magnetic pickups sensing a toothed wheel feed turbine speed data in, potential transformers provide generator and bus voltage for synchronizing, and once conditions are matched, the board energizes the 125 V DC generator breaker coil (52G) through a chain of permissive relays — K25, K25P, and K25A. All of this field wiring — pickups, shaft sensors, PTs, and breaker relay leads — lands on two 24-terminal blocks, TB1 and TB2, while the board connects by cable to the VTUR card in the R/S/T Control Module through six D-type connectors (JR1/JR5, JS1/JS5, JT1/JT5).

If You're Seeing a Shaft Voltage Alarm, Read This First

A shaft voltage or shaft current alarm is one of the clearest cases in this whole product family where the terminal board is very likely not the problem:

• The TTUR and VTUR only monitor shaft-to-ground voltage and current — they don't generate the condition. An alarm almost always points to a grounding brush that needs cleaning or replacement, or a bearing insulation issue on the physical shaft train, not a defect in this board.
• Use the board's built-in DC and AC test circuits to confirm wiring continuity before assuming a hardware fault.
• Separately, for synchronizing issues, check the external synch check relay, the 52G/a breaker feedback contact, PT wiring/fuses, and the JP1/JP2 simplex/TMR jumper settings.
• For erratic speed readings, check the magnetic pickup air gap and cabling to TB1/TB2 before assuming the board itself has failed.

Reading the IS200TTURH1BCC Part Number

IS200 is the platform prefix, TTUR the function code, and H1BCC the group and revision — H1B for the group/generation, CC for this specific revision. Quote and order against the full string; the H1B and H1C TTUR groups in this collection are distinct hardware generations. Our GE Speedtronic Part Number Decoder explains how a complete IS200 part number is built.

Related Boards

The TTUR's companion VME card is VTUR, in the Control Module. The generator breaker trip circuit runs through the TRPG terminal board (driven by VTUR) and the TREG terminal board in the Backup Protection Module (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: IS200TTURH1BCC
• 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 IS200TTURH1BCC 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	GE General Electric IS200TTURH1B IS200TTURH1BCC Termination PC Board Mark VI
Condition	used Cleaned and Tested. With 1 Year Warranty.