GE IS200 Modules — IS200SRTDH2ACV Simplex Terminal Relay Board

Technical Dossier

Product Details And Specifications

GE IS200 Series: Comprehensive Module Range and Technical Overview

The GE IS200 series constitutes the core I/O, relay, communication, and power distribution hardware of GE's Mark VI Turbine Control System and the EX2100 Excitation Control platform. Deployed across heavy industrial sectors — including petrochemical refineries, nuclear power stations, combined-cycle gas turbine plants, and offshore oil & gas facilities — the IS200 series represents one of the most widely installed distributed control architectures in global power generation infrastructure. Installed base estimates exceed tens of thousands of units across North America, Europe, the Middle East, and Asia-Pacific. The modular backplane architecture allows individual boards to be replaced without full system shutdown, making spare parts availability a critical operational concern for plant maintenance teams operating under long asset lifecycles (20–40 years).

The Evolution of IS200 Architecture

The IS200 hardware lineage originates from GE's SPEEDTRONIC Mark V platform (late 1980s), which used discrete relay logic and analog signal conditioning. The Mark VI (introduced mid-1990s) transitioned to a fully digital, triple-redundant (TMR) or simplex architecture using the IS200 board family over a VME-derived backplane with proprietary IONet and ARCNET communication buses. Key architectural milestones include the introduction of the VCMI (VME Communication Module Interface) for inter-controller communication, the PPRO processor board for real-time turbine sequencing, and the relay terminal boards (SRLY, SRTD families) for hardwired trip and alarm circuits. The EX2100 excitation control system shares a significant subset of IS200 boards, particularly in the analog I/O and power supply domains. Compatibility constraints are strict: IS200 boards are not interchangeable with IS215 (Mark VIe) boards without firmware and backplane adapter changes. Plants migrating from Mark VI to Mark VIe must conduct full I/O mapping audits. The IS200 series entered the mature/end-of-active-production phase circa 2015, with GE transitioning new installations to the Mark VIe (IS215 series). However, the installed base remains extensive, and GE Vernova (formerly GE Gas Power) continues to offer limited OEM support. Third-party MRO suppliers such as DriveKNMS provide lifecycle extension services for obsolete and hard-to-find IS200 variants.

IS200 Full Catalog & Functionalities (SKU List)

The following IS200 series modules are classified by functional category. Each SKU represents a verified, commonly stocked component within the Mark VI / EX2100 control architecture.

Relay & Terminal Boards

• IS200SRTDH2ACV: Simplex terminal relay board; hardwired relay output interface for Mark VI turbine trip and alarm circuits.
• IS200SRLYH1ACD: Simplex relay output board; 16-channel relay driver for discrete output signals in Mark VI simplex configurations.
• IS200STCIH1ACD: Terminal board for thermocouple inputs; cold-junction compensated analog input conditioning for up to 12 TC channels.
• IS200SRTDH1ACD: Simplex terminal relay board variant H1; earlier revision of the SRTD family with identical relay output topology.

Analog I/O Modules

• IS200AEPAH1ACD: Analog I/O expansion board; provides additional 4–20 mA input/output channels for process variable monitoring.
• IS200AEAAH1ACD: Analog input board; 16-channel differential analog input module for pressure, flow, and temperature transmitters.
• IS200AEAAH2ACD: Analog input board revision H2; updated isolation and filtering specifications versus H1 variant.
• IS200AEPAH2ACD: Analog I/O expansion board H2; revised PCB layout with enhanced EMI shielding.

Digital I/O Modules

• IS200EDCFH1ACD: Digital contact input board; 24 VDC discrete input module for valve position and limit switch feedback.
• IS200EDCFH1ACA: Digital contact input board variant A; alternate voltage rating configuration for 120 VAC field wiring.
• IS200EACFH1ACD: AC digital input board; 120/240 VAC contact input module for high-voltage field device interfacing.
• IS200EPCTG1ACD: Pulse count input board; high-speed pulse accumulator for turbine speed and flow meter signals.

Processor & Communication Modules

• IS200VPROH1ACD: VME processor board (PPRO); primary real-time control processor running Mark VI turbine sequencing firmware.
• IS200VCMIH2ACD: VME communication module interface H2; manages IONet Ethernet and ARCNET inter-controller data exchange.
• IS200VCMIH1ACD: VME communication module interface H1; earlier VCMI revision; functionally equivalent with older firmware baseline.

Power Supply Modules

• IS200EPSMH1ACD: Power supply module; 28 VDC regulated output for IS200 backplane and I/O board power distribution.
• IS200EPSMH2ACD: Power supply module H2; updated switching topology with improved transient suppression and higher MTBF rating.

Sourcing Hard-to-Find & Obsolete IS200 Parts

Quality Control for the IS200 Range

IS200 boards present specific test challenges due to their multi-layer VME backplane interface, proprietary ARCNET/IONet communication stacks, and mixed analog-digital signal paths. DriveKNMS applies a structured test protocol for all IS200 units prior to shipment. Relay output boards (SRTD, SRLY families) undergo coil continuity measurement, contact resistance verification (<100 mΩ per contact), and dielectric withstand testing at 1500 VAC for 60 seconds. Analog I/O boards are bench-tested against GE's published accuracy specifications using calibrated signal sources traceable to NIST standards. Processor and communication boards (PPRO, VCMI) are powered in a live Mark VI test rack and validated for IONet enumeration, firmware version integrity, and inter-board communication handshake. All boards are inspected for capacitor ESR degradation, solder joint integrity under 10× magnification, and conformal coating condition. Units failing any test parameter are quarantined and not offered for sale.