IS200FGPAG1A - Gate Pulse Amplifier Board

Functional Description

IS200FGPAG1A is a Gate Pulse Amplifier Board developed by General Electric. It is a part of the EX2100 Excitation system. The FGPA is the gate driver, switching power supply, and SCR status monitors for the LCI. The LCI control sends gating commands to the board (via fiber-optic cables). Each FGPA provides sufficient gate power and duration for one phase of an SCR bridge. This is sent to CTs on the FHVA boards, which interface with the SCRs.

Features
The switching power supply circuit converts alternating current input to the alternating current control voltages required for status and gating functions. It takes a 120 V alternating current input from a power supply and outputs the following voltages:

• P5 (4.7 - 5.1 V dc) logic power supply
• No monitoring of P15 (13.5 - 14.5 V dc)
• P40 (25 V dc) for back porch gate
• To begin gating, use P90 (80 V dc)

Characteristics

• The control is interfaced to the Power Bridge via the board. The component receives gate commands from the controller's board and generates gate-firing pulses for six SCRs (Silicon Controlled Rectifiers). It also serves as an interface for current conduction feedback as well as bridge airflow and temperature monitoring. An RTD is used on a new exciter to monitor temperature and generate alarms. Additional switches activated by fan rotation track the flow of cooling air across the bridge.
• The exciter may accept feedback from two thermal switches mounted on the SCR heatsink assemblies in an exciter controls only retrofit. At the alarm level, one thermal switch opens, and the other at the trip level. These switches are connected to the board and may need retrofitting into the existing bridge. A bridge overtemperature alarm is generated if either switch is opened. A fault and a trip are generated if both switches are open.