IS210TREGH4B - Terminal Board Assembly

IS210TREGH4B - Terminal Board Assembly IS210TREGH4B - Terminal Board Assembly

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Part Number: IS210TREGH4B
Manufacturer: General Electric
Series: Mark VI
Product Type: Emergency Trip Terminal Board Assembly
Repair: 3-5 days
Trip interlock isolation: Optical isolation to 1500 V on all inputs
Trip interlock filter: Hardware filter, 4 ms
Trip interlock ac voltage rejection: 60 V rms
Size: 17.8 cm wide x 33.02 cm high
Solenoid response time: Solenoid L/R time constant is 0.1 second
Suppression: MOV across the solenoid
Availability: In Stock
Country of Manufacturer: United States (USA)

Functional Description

IS210TREGH4B is an Emergency Trip Terminal Board Assembly developed by General Electrics. It is a part of Mark VI control system. The TREG system plays a critical role in ensuring the safety and functionality of various emergency functions within a larger system. Specifically, it serves as the power source for three emergency trip solenoids, all of which are under the precise control of the I/O controller.


  • Responsible for supplying power to the three emergency trip solenoids. These solenoids are crucial for triggering essential safety measures in response to specific conditions or events.
  • Designed to accommodate up to three trip solenoids, and these solenoids are connected between the TREG and TRPG terminal boards. Each solenoid is strategically positioned to respond to distinct emergency scenarios.
  • Provides the positive side of the direct current (DC) power to the connected solenoids. This positive power supply is essential for energizing and activating the solenoids when required.
  • To complete the circuit and ensure proper functionality, the TRPG terminal boards come into play by providing the negative side of the DC power. This complementary power source from TRPG is essential for enabling the solenoids to perform their emergency trip functions effectively.
  • The I/O controller takes on a central role in the operation of this system. It is responsible for overseeing and managing several critical functions:
    • Emergency Overspeed Protection: The I/O controller monitors the speed of the system and can engage emergency overspeed protection measures to prevent dangerous acceleration.
    • Emergency Stop Functions: In case of any critical issues or emergencies, the I/O controller can initiate emergency stop functions to halt the system immediately.
    • Relay Control: TREG hosts a set of 12 relays, and the I/O controller is in charge of controlling these relays. Nine of these relays are organized into three groups of three. These relay groups work in a voting system, where the inputs are assessed collectively, ensuring redundancy and reliability. This mechanism allows for effective control of the three trip solenoids, enhancing safety and response capabilities.


The operation of the TREG system is highly streamlined and reliant on the precise control provided by the I/O controller. This control scheme ensures the safety and functionality of the entire system, with minimal external connections to the control modules. 

  • I/O Controller Dominance: The I/O controller serves as the central brain of the system, exercising complete authority over its functions. It orchestrates and coordinates all actions and responses, making it a crucial component for the system's overall performance and safety.
  • Control Module Connections: TREG maintains a minimalist approach when it comes to external connections. The only two connections it has to the control modules are as follows:
    • J2 Power Cable: This cable is responsible for supplying power. It acts as the lifeline that ensures TREG remains operational and ready to respond to emergency situations. This power connection is fundamental to keeping the system active and prepared for action.
    • Trip Solenoid Connections: The primary means through which TREG interacts with the wider system is through the trip solenoids. These solenoids are crucial for initiating emergency shutdowns or other critical actions when necessary. The control signals from the I/O controller are transmitted through these solenoids, enabling precise and rapid responses to emergency conditions.
  • Simplex System Functionality: In simplex systems, an additional cable, known as the third cable, comes into play. This cable carries a trip signal from J1 to the TSVO terminal board. This trip signal is particularly important because it facilitates a servo valve clamp function when the turbine undergoes a trip event. This feature is critical for ensuring that the turbine is safely brought to a stop or controlled state during emergency scenarios.
  • In essence, TREG's operation is characterized by its reliance on the I/O controller for control and coordination. Its connections are kept minimal and purpose-driven, with power supply through the J2 cable and communication via the trip solenoids. In simplex systems, the introduction of the third cable adds an extra layer of safety by enabling precise control of the servo valve during turbine trip events. This careful design and control strategy make TREG an integral component in maintaining the safety and reliability of the larger system it is a part of.

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What is IS210TREGH4B?
It is a Emergency Trip Terminal Board Assembly developed by General Electrics.

What is the purpose of the application software in the controller?
The application software in the controller is designed to initiate tests of the trip solenoids. It allows for the systematic testing of these critical components to ensure they function as intended during emergency scenarios.

What are online tests for trip solenoids?
Online tests are procedures that enable each of the trip solenoids to be manually tripped one at a time. These tests can be conducted either through the PTR relays from the controller or through the ETR relays from the protection module.

Why is it important to be able to manually trip the solenoids one at a time?
Being able to manually trip solenoids individually is crucial for diagnostic purposes and for verifying that each solenoid responds correctly to the triggering signal. This ensures that the safety system is fully functional.