IS200DSPXH1D & IS200EMIOH1A are the Control and I/O Board in the GE EX2100 Control System. The IS200DSPXH1C Digital Signal Processor Control Board (DSPX) serves as the primary controller for the bridge rectifier, motor regulator, and gating functions of InnovationSeries drives. It also controls the excitation function of the EX2100 exciter. The IS200DSPXH1CAA(IS200DSPXH1DBD) board performs most of the I/O interface and inner-loop bridge control and protection functions. The IS200EMIOH1ACA exciter main I/O board (EMIO) is primarily used to control pilot relays and gating, as well as to send commands to the ESEL board. The IS200EMIOH1A is a single-slot, double-height VME-type board that manages I/O from the EPCT, ECTB, EACF, and EXTB terminal blocks. I/O includes PT and CT signals, contact inputs, output relay drivers, and pilot trip relay drivers. The IS200EMIOH1A input/output board also sends logic-level gate pulse signals to the ESEL board via the backplane, and the ESEL board then sends these signals to the EGPA in the power conversion cabinet.

GE's EX2100 excitation system is a flexible, modular system that can be assembled to provide a range of available output currents and multiple levels of system redundancy. These options include power supplies from potential sources, composite sources, or auxiliary power supplies. Single-bridge or multi-bridge, hot-standby bridge, and simplex or redundant control are available. An overview of the turbine generator excitation system is shown in the figure below. The exciter is powered by a power potential transformer connected to the generator terminals or by an excitation transformer connected to the auxiliary bus. Generator line current and stator output voltage are the primary feedbacks to the exciter, while DC voltage and current are the controlled outputs of the exciter's magnetic field. This architecture supports Ethernet LAN (cell data highway) communication with other GE devices, including the GE Control System Toolbox (Toolbox) for configuration, the turbine control system, the LCI static starter, and the Human-Machine Interface (HMI).

The following figure is a simplified single-line diagram of the exciter, showing the power supply, generator current and voltage measurements, control modules, power conversion modules (PCMs), and protection circuitry. In the potential source system, the secondary side of the PPT is connected to the input of a three-phase full-wave inverter thyristor bridge. This inverter bridge provides both positive and negative excitation voltages for optimal performance. Negative excitation enables fast response for load shedding and de-excitation. Simplex or redundant control modes are selectable. Excitation control is achieved through phase control of the SCR bridge circuit output. The SCR trigger signal is generated by a digital regulator in the controller. In the redundant control option, M1 or M2 can act as the active master controller, while C monitors both to determine which is the active controller and which is the standby controller. The system employs dual independent trigger circuits and automatic tracking to ensure a smooth switchover to the standby controller.

The EX2100 hardware comprises the following three cabinets:

1. Control cabinet, containing the keyboard control rack, control power distribution module and power supply, and I/O terminal blocks.
2. Auxiliary cabinet, for field flashing and protection circuits, such as de-excitation and shaft voltage suppression.
3. Power conversion cabinet, for power SCR units, cooling fans, DC contactors, and AC circuit breakers. The exciter's power converter consists of a bridge rectifier, a resistor/capacitor filter configuration, and control circuitry. The dimensions of the components and bridge rectifier vary depending on the excitation system and required power output.

A diagnostic interface (keyboard) provides a second keypad for redundant control. The keypad is a local operating interface mounted on the control cabinet door. Start/stop commands, regulator switching commands, and regulator activation commands can all be issued via the keypad. The keypad also includes instrument displays indicating system status, such as the generator's megawatt (MW) and reactive power (MVAR), excitation current and voltage, and regulator balance status. Diagnostic displays (e.g., alarm history displays) provide system information for maintenance and troubleshooting.

The control module is a VME-type rack with onboard cables connecting to the I/O terminal block. This rack is divided into three independently powered sections for the M1, M2, and C controllers. Each controller contains a control board and an I/O processor board. If the rack contains only the M1 controller, it is a simplex control system; if the rack contains all three controllers, it is a redundant control system. The IS200DSPXH1D & IS200EMIOH1A are the  Control& I/O Board In this Control Cabinet. The control and I/O processor boards are as follows:

• Microprocessor-based Application Control Layer Module (ACLA) controller with LAN Ethernet port
• Microprocessor-based Digital Signal Processor (DSPX) controller
• Exciter ISBus board (EISB), communicating with the bridge feedback board via fiber optic cable
• Exciter Main I/O board (EMIO), used to control the sending of commands to the ESEL board via pilot relays and gating
• Exciter Selector board (ESEL), used to distribute gating pulses from the active controller to the EGPA

Simplex Control System

The interconnection between the simplex control system and the terminal board, generator protection module, and power supply is shown in the following diagram. Only one EPSM power supply is used, but this power supply can provide both AC and DC power simultaneously to improve reliability.

Redundant Control System

The redundant control system consists of three controllers and three redundant power supplies, one for each controller. The power supply rack also contains three grounding detector modules. The diagram below shows three EDCF boards; three EPCT boards can also be used if needed.

Controller C Redundant System

Controller C is used only in redundant systems. It is mounted in the control rack and its physical structure is similar to that of controllers M1 and M2, but C does not handle bridge triggering and therefore does not contain an ESEL or ACLA board. Controller C receives the same feedback voltage and current inputs as other controllers and contains similar software. Its purpose is to monitor the primary and backup controllers (M1 or M2) and initiate appropriate protection responses when system conditions exceed set values. It defines the regulatory boundaries. Input and output signal voting is performed across all three controllers, which are connected in a three-module redundancy (TMR) controller configuration. Each controller contains up to six boards interconnected via a backplane. And when Controller C redundancy mode is selected, IS200DSPXH1C or IS200DSPXH1D is the only control board option.

Control Power Supply
The controllers are powered by the Exciter Power Distribution Module (EPDM). This module is powered by one 125V DC power supply and one or two 115V AC power supplies. The AC power is passed through an AC/DC converter (DACA). The resulting 125V DC power is coupled to the other DC power supplies via diodes to form a DC bus that powers the control module and gate pulse amplifier board. The EPDM's fuse outputs power the EGPA board, EXTB, and Exciter Power Backplane (EPBP). Each output is equipped with an LED indicator and an isolating switch. The EPDM is mounted on the left side of the Exciter Power rack. Up to three Exciter Power Modules (EPSMs) can be mounted on the EPBP backplane, providing logic-level power to the controllers. The EPSM is powered by a 125 V DC supply from the EPDM and generates +5 V DC, ±15 V DC, and +24 V DC power supplies. Additionally, there is an isolated 70 V DC output for contact wetting by the EXTB and ECTB. Up to three ground detection modules (EGDMs) can be installed in the EPBP. These modules communicate with the EXAM module located in the auxiliary cabinet.