GE IS200ESELH2A IS200ESELH2AAA | Exciter Selector Board

Core Function and System Role

The GE IS200ESELH2A selects and fires SCRs for Mark VI exciter systems. Specifically, this board routes firing pulses to the appropriate thyristor bank. Moreover, it provides isolation between logic and power circuits. The IS200ESELH2AAA variant includes enhanced gate drive for high-power applications.

Technical Specifications Overview

This exciter selector board features six independent SCR output channels. Each channel delivers 2 A peak gate current for reliable switching. Furthermore, the board provides 2500 Vrms isolation between input and output.

Parameter	Specification
Part Number	IS200ESELH2A / IS200ESELH2AAA
Type	Exciter Selector Board / SCR Firing Module
Gate Outputs	6 Channels
Peak Gate Current	2 A per Channel
Gate Voltage	15 Vdc Open Circuit
Isolation Voltage	2500 Vrms
Input Signal	TTL, 5 Vdc
Propagation Delay	<1 µs
Selector Logic	2-of-6 Programmable
Logic Power Supply	24 Vdc ±15%
Connector Types	2 x 50-pin D-sub, 1 x Terminal Block
Dimensions (W x H x D)	195 x 115 x 32 mm
Weight	0.72 kg
Onboard Energy Storage	6 x 680 µF, 80V Capacitors

Connector Layout and Component Count

The board uses two 50-pin D-sub connectors for control interfaces. For instance, connector P1 receives firing pulse commands from the regulator. Meanwhile, connector P2 routes gate current to external SCR stacks. A separate terminal block supplies 24 Vdc logic power. The IS200ESELH2AAA adds six high-current MOSFET drivers on the output stage.

Energy Storage and Pulse Integrity

This selector board includes local capacitance for consistent gate drive. Specifically, six 680 µF capacitors store energy for each output channel. Therefore, the board delivers full gate current even during AC line sags. Additionally, onboard LED indicators show each channel’s selection status. For example, green LEDs illuminate for active firing channels. Yellow LEDs indicate standby or deselected channels.

Diagnostic Features and Fault Protection

The board continuously monitors each gate for proper current flow. Consequently, it detects open gate conditions within 1 microsecond. Moreover, the GE IS200ESELH2A IS200ESELH2AAA includes desaturation detection on all output transistors. This feature prevents damage from output short circuits. An onboard fault relay reports any channel error to the main controller.

Maintenance and Hot Replacement

You can replace this selector board without shutting down the exciter system. Thus, mean time to repair remains under fifteen minutes. The board stores no calibration data locally. Therefore, you simply install the replacement and resume normal firing control.

Industrial Applications

This exciter selector board works inside GE Mark VI excitation panels. For reliable GE SCR firing, the IS200ESELH2A and IS200ESELH2AAA deliver exceptional performance. They provide robust gate drive selection for steam and gas turbine generator exciters.