GE Mark VI Modules

Technical Dossier

Product Details And Specifications

GE Mark VI Series: Comprehensive Module Range and Technical Overview

The GE Mark VI Turbine Control System is a distributed control platform developed by GE Energy (now Baker Hughes GE) for gas turbine, steam turbine, and combined-cycle power generation applications. Deployed across chemical processing plants, nuclear auxiliary systems, offshore platforms, and petroleum refineries worldwide, the Mark VI represents the industrial standard for turbine sequencing, protection, and condition monitoring. Its triple-redundant TMR (Triple Modular Redundancy) architecture and dual-redundant simplex configurations make it the reference platform for critical rotating equipment control in facilities where unplanned downtime carries multi-million-dollar consequences. Installed base spans over 10,000 units globally across GE Frame 3 through Frame 9 gas turbines, as well as steam turbine applications in combined heat and power (CHP) plants.

The Evolution of Mark VI Architecture

The GE turbine control lineage begins with the Mark I relay-based system of the 1960s, progressing through the Mark II (analog electronics), Mark III (early digital), and Mark IV (microprocessor-based) platforms. The Mark V, introduced in the late 1980s, established the distributed I/O model and ARCNET communications backbone that defined the series. The Mark VI, released in the mid-1990s and refined through the 2000s, replaced ARCNET with the IONet Ethernet-based I/O bus and introduced the UCSC (Unit Controller Simplex/Core) and VCMI (VME Communications Module Interface) architecture. The Mark VIe followed, adopting IEC 61131-3 programming standards and Ethernet-based I/O over the IONet protocol, enabling integration with modern DCS platforms including GE's own Proficy HMI/SCADA. Compatibility between Mark V and Mark VI is limited to physical rack dimensions and some terminal board pinouts; firmware and communication protocols are not interchangeable. Facilities running Mark V hardware that migrate to Mark VI must replace all controller cards while potentially retaining terminal boards and field wiring, a critical cost consideration for lifecycle planning.

Mark VI Full Catalog & Functionalities (SKU List)

The following verified SKUs represent the core module population of the GE Mark VI platform, organized by functional category. Each module is a discrete line-replaceable unit (LRU) within the Mark VI I/O rack or controller chassis.

Controller / CPU Modules

• IS200UCVEH2A: Unit Controller VME — primary CPU card for simplex and TMR configurations, runs turbine sequencing logic.
• IS200UCVEH2B: Revised spin of UCVEH2A with updated FPGA firmware; direct drop-in replacement.
• IS200TSVOH1A: Turbine Supervisory I/O module — interfaces vibration, eccentricity, and speed probes to the controller.
• 151X1249BR01SA01: Control module assembly — board-level controller card used in Mark VI simplex turbine control racks; manages sequencing and protection relay outputs.

Analog Input / Output Modules

• IS200AAIAH1A: Analog Input module — 16-channel, 4–20 mA / 0–10 V configurable, used for temperature and pressure transmitter inputs.
• IS200AAOAH1A: Analog Output module — 8-channel, 4–20 mA, drives control valves and actuator positioners.
• IS200ATAIH1A: Thermocouple Analog Input module — 16-channel, supports J, K, T, E, R, S, B type thermocouples with cold junction compensation.
• IS200TRLYH1A: Relay Output module — 16-channel relay outputs for trip and alarm functions, rated 250 VAC / 30 VDC.

Digital Input / Output Modules

• IS200DAIAH1A: Digital Input module — 24-channel, 24 VDC discrete inputs for limit switches, pressure switches, and position feedback.
• IS200DAOAH1A: Digital Output module — 24-channel, 24 VDC sourcing outputs for solenoid valves and relay coils.
• IS200EDCFH1A: Excitation and DC Field module — interfaces generator excitation systems to the Mark VI controller.

Communication / Network Modules

• IS200VCMIH2C: VME Communications Module Interface — primary IONet Ethernet bridge card; connects I/O packs to the UCSC controller over 10/100 Mbps Ethernet.
• IS200VCMIH2D: Updated revision of VCMIH2C with enhanced EMI filtering and revised MAC address allocation.
• IS200EPCTG1A: Ethernet Patch Card — provides redundant IONet port switching within the Mark VI rack backplane.
• IS200STCIH1A: Serial Communications Interface — RS-232/RS-485 module for Modbus RTU integration with third-party instrumentation.

Power Supply Modules

• IS200PSCDH1A: DC Power Supply module — 28 VDC regulated output, supplies I/O pack rails within the Mark VI chassis.
• IS200PSCAH1A: AC/DC Power Converter — accepts 120/240 VAC input, outputs 28 VDC for controller and I/O rack power distribution.
• IS200TTURH1A: Turbine Terminal Unit Relay board — interfaces field trip solenoids and provides hardwired overspeed protection relay outputs.

Sourcing Hard-to-Find & Obsolete Mark VI Parts

GE formally transitioned Mark VI support to Baker Hughes GE (BHGE) following the 2017 merger. As of 2024, the Mark VI platform is classified as a mature/end-of-active-development system, with GE Digital and BHGE offering migration paths to the Mark VIe and Mark VIeS. New manufacture of many Mark VI board-level assemblies has ceased, making the secondary market the primary source for like-for-like replacements.

DriveKNMS maintains a dedicated inventory of Mark VI modules sourced from decommissioned turbine control panels, surplus OEM stock, and certified repair facilities. For modules such as the 151X1249BR01SA01, IS200UCVEH2A, and IS200VCMIH2C — which are no longer available through standard distribution channels — DriveKNMS provides verified pull-tested units with full traceability documentation. Lead times for in-stock items are typically 1–3 business days for international shipment. For units requiring board-level repair, turnaround is 7–15 business days depending on fault complexity.

Quality Control for the Mark VI Range

Mark VI modules present specific test challenges due to their VME backplane architecture, IONet Ethernet dependency, and FPGA-based I/O processing. DriveKNMS applies the following test protocol to all Mark VI units prior to shipment:

• Visual inspection: BGA solder joint integrity, capacitor ESR check, conformal coating condition assessment.
• Backplane continuity test: All VME bus lines verified against GE schematic reference for the specific board revision.
• Powered functional test: Module inserted into a live Mark VI test rack running GE ToolboxST software; I/O channels exercised at rated signal levels.
• IONet communication verification: VCMI and UCSC modules tested for successful IONet enumeration and data exchange at 100 Mbps.
• Firmware revision check: FPGA and embedded firmware versions logged and matched to GE compatibility matrix for the target turbine application.
• Burn-in: 48-hour continuous operation under simulated I/O load prior to final inspection and packaging.

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