IS200TRELH2A - Terminal Board

IS200TRELH2A - Terminal Board IS200TRELH2A - Terminal Board

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Part No.: IS200TRELH2A
Manufacturer: General Electric
Series: Mark VIe
Size 17.8 cm wide x 33.02 cm high
Number of trip solenoids: 3
Trip solenoid rating: 24 V dc is alternate with 3 A draw
Availability: In Stock
Country of Manufacture: United States (USA)

Functional Description

IS200TRELH2A is a Turbine Turbine Emergency Trip Terminal Board developed by GE. It is a part of Mark VIe control system. The Large Steam Turbine Emergency Trip terminal board plays a crucial role in ensuring the emergency overspeed protection for large steam turbines. This component is tightly integrated into the system's safety measures, controlled by the VPRO within the protection module.


  • TREL operates by supplying power to three emergency trip solenoids, which can be strategically connected between the TREL and TRPL terminal boards. The positive side of the 125 V dc power required for these solenoids is provided by TREL, while the negative side is sourced from TRPL. This dual-sided power supply arrangement ensures the reliable operation of the emergency trip solenoids.
  • In terms of functionality, the I/O controller takes on a central role in managing operations. It oversees the emergency overspeed protection measures, controls the emergency stop functions, and is responsible for the operation of the nine relays situated on the board. These nine relays are organized into three distinct groups of three, which collectively vote on inputs that ultimately govern the actions of the three trip solenoids. These groups are identified as ETR (emergency trip) 1, 2, and 3, each contributing to the robust emergency trip mechanism.
  • It is available in a Triple Modular Redundant (TMR) form, underscoring the high level of redundancy and fault tolerance built into its design. Unlike its counterpart, TREG, TREL lacks an economizing relay, as its primary focus is on rapid and effective emergency trip responses.
  • It does not incorporate the E-STOP (emergency stop) function present in TREG. Instead, its primary mission is to handle emergency overspeed scenarios and provide a critical layer of protection to large steam turbines.
  • For enhanced system reliability, a second board can be deployed and operated in conjunction with the protection module, ensuring redundancy and increasing the system's ability to respond effectively to emergency situations.


  • Wiring of Trip Solenoids: The first critical step involves wiring the three trip solenoids. These solenoids play a pivotal role in the system's operation, and they are connected to the first I/O terminal block. This connection ensures that the solenoids can be controlled and activated as needed.
  • Trip Interlock Connections: To enhance the system's safety and functionality, up to seven trip interlocks are wired to the second terminal block. These interlocks are vital for monitoring and safeguarding various aspects of the system's operation. Wiring them to the second terminal block allows for effective integration and control.
  • Reference to Wiring Diagram: The precise wiring connections for both the trip solenoids and trip interlocks are detailed in a comprehensive wiring diagram. This diagram serves as a visual reference, illustrating the specific paths and connections required for proper installation.
  • Connector J2: Connector J2 serves as a crucial element in the installation. It carries three power buses originating from TRPL. These power buses are essential for supplying power to various components within the system, including the trip solenoids. Proper connection to J2 ensures a reliable power source for these critical components.
  • Connector JH1: Another important connector in the installation is JH1, which carries the excitation voltage required for the seven trip interlocks. This voltage is essential for the interlocks to function effectively and monitor the system's status.
  • Testing and Verification: Once all the connections are made as per the wiring diagram, thorough testing and verification procedures are carried out. These tests ensure that all components are properly connected and functioning as intended, validating the integrity and reliability of the installation

World of Controls has the most comprehensive collection of GE Mark VIe components. Please contact WOC as soon as possible if you require any extra information.


Frequently Asked Questions


What is IS200TRELH2A?
It is an Turbine Turbine Emergency Trip Terminal Board developed by GE

What is the purpose of the protection module running diagnostics on the board and connected devices?
The protection module conducts diagnostics on the board and its connected devices to ensure their proper functioning and to detect any faults or discrepancies that may compromise the system's integrity and safety.

What specific components and parameters are covered by these diagnostics?
The diagnostics cover a range of critical parameters, including the trip relay driver and contact feedbacks, solenoid voltage, K25A relay driver and coil, servo clamp relay driver and contact feedback, and the solenoid voltage source.

What happens if the diagnostic results do not align with the desired values?
If any of the diagnostic results deviate from the expected or desired values, a fault is generated within the system. This fault serves as an alert that something is amiss and requires attention or troubleshooting.

Can you explain the role of TREL connectors JX1, JY1, and JZ1?
TREL connectors JX1, JY1, and JZ1 are equipped with ID devices. These ID devices are read-only chips that contain important information such as the terminal board's serial number, board type, revision number, and plug location.