GE DS200FGPAG1AFC LCI Gate Pulse Amplifier Card
Description:
DS200FGPAG1A is the LCI's gate driver, switching power supply, and SCR status monitor. The board receives gating commands from the LCI control (via fiber-optic cables).  Each DS200FGPAG1A supplies gate power of sufficient magnitude and duration for one phase of an SCR bridge. It sends this to CT's on the FHVA boards, which provide an interface to the SCRs.
The switching power supply circuit converts ac input to the de control voltages required for status and gatingfinctions. It receives 120 V ac input from a power supply and produces the following voltages:
· P5(4.7-5.1 V dc) for logic power
· P15(13.5-14.5 V de) not monitored
· P40(25 V dc) for gate “back porch'
· P90(80 V dc) to start gating
As a status monitor, the DS200FGPAG1AFC accumulates SCR voltage information from the FHVA boards, andtransmits the data to the LCI control. This includesstatus of the switching power supply. Each gate driver utilizes a push-pull circuit driving a cen-ter-tapped transformer primary to produce an AC output current signal. The secondary of the transformer is con-nected to output stabs AGATEl and AGATE2. Currentfrom AGATEl flows through a conductor to the isolation CT on DS200FHVA. The conductor is routed through the window of each isolation CT to create a single-turm pr1-mary winding and back to AGATE2. The AGATE2 stabis grounded through stab AGND. The frequency of the output is approx1-mately 33 Khz. The CT on the FHVA card has a 5 turn secondary connected to the input of a full wave diode bridge. This combination steps the ac current from FGPA down by a ratio of 5:1, then rectifies and sends the resulting dc current on to the SCR gate.