IS200EHPAG1DAB is part of GE EX21000 series Gate Pulse Amplifiers. IS200EHPAG1DAB board (for 100mm systems) interfaces the control tothe Power Bridge. IS200EHPAG1DAB takes the gate commands from the ESEL board in the controller, and generates the gate firing pulses for six SCRs (Silicon ControlledRectifiers). It is also the interface for current conduction feedback, and bridgeairflow and temperature monitoring.

The gate pulse amplifiers directly control the SCRs.

An RTD is used to monitor the bridge temperature and generate alarms. Additional sensors actuated by fan rotation monitor cooling airflow across the bridge. On anexciter controls only retrofit, the exciter may have provisions for accepting feedbackfrom two thermal switches mounted on the SCR heatsink assemblies. One thermalswitch opens at the alarm level (170 °F (76°C)) and the other at the trip level (190 °F(87°C)). These switches are wired to the EGPA board and may require retrofittinginto the existing bridge. If either switch opens, a bridge overtemperature alarm isgenerated. If both switches open, a fault and a trip are generated.