Description
Key Technical Specifications
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Model Number: DS200EXPSG1ACB
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Manufacturer: General Electric
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Input Bus: 125 VDC ±20 % from Mark V power shelf
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Outputs: +5 V @ 20 A, +15 V @ 3 A, –15 V @ 3 A
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Efficiency: 82 % typical, fan-cooled 50 CFM required
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Protection: 3 A GMT fuses per rail, fold-back current limit
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Hold-up Time: 20 ms @ full load at 125 VDC
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Ripple: 50 mV p-p on 5 V rail, 100 mV on ±15 V
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Isolation: 1 kV input-to-output, 500 V rail-to-rail
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Connectors: J1 125 VDC input, J2/J3 9-pin output distribution, J4 alarm
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Indicators: Green power-good LED, red fuse fault LED
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Operating Temperature: 0 – 70 °C with 300 LFM airflow
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Coating: Enhanced (ACB) acrylic for paper-mill H₂S duty
GE DS200SDCIG1A
Field Application & Problem Solved
Static-start EX2000 racks die quickest when the bulk supply folds. Logic crashes first, then gate drive collapses and the whole bridge faults on under-voltage. The DS200EXPSG1ACB is the brick that keeps that from happening. It lives in the lowest slot of the inverter rack, pre-regulates 125 VDC down to the three rails the rest of the cards need, and does it with enough head-room to ride through a 200 ms DC dip when the battery charger hiccups. You’ll find one in every EX2100 exciter cubicle and legacy Mark V static starter. Its real value: it isolates the 125 V battery bus from sensitive logic and gives you independent fuses so a shorted encoder cable doesn’t drag down the entire rack. In fifteen years I’ve never lost a turbine on this board—when it dies it announces itself, you hot-swap it, and you’re back online in six minutes.
Static-start EX2000 racks die quickest when the bulk supply folds. Logic crashes first, then gate drive collapses and the whole bridge faults on under-voltage. The DS200EXPSG1ACB is the brick that keeps that from happening. It lives in the lowest slot of the inverter rack, pre-regulates 125 VDC down to the three rails the rest of the cards need, and does it with enough head-room to ride through a 200 ms DC dip when the battery charger hiccups. You’ll find one in every EX2100 exciter cubicle and legacy Mark V static starter. Its real value: it isolates the 125 V battery bus from sensitive logic and gives you independent fuses so a shorted encoder cable doesn’t drag down the entire rack. In fifteen years I’ve never lost a turbine on this board—when it dies it announces itself, you hot-swap it, and you’re back online in six minutes.
Installation & Maintenance Pitfalls (Expert Tips)
Airflow is Not Optional
The heatsink is sized for 300 LFM. Block one fan filter and the sink hits 85 °C in twenty minutes; the fold-back cuts 5 V to 4.6 V and the CPU starts random resets. Vacuum the filters every outage or you’ll chase phantom “CPU HALT” alarms.
The heatsink is sized for 300 LFM. Block one fan filter and the sink hits 85 °C in twenty minutes; the fold-back cuts 5 V to 4.6 V and the CPU starts random resets. Vacuum the filters every outage or you’ll chase phantom “CPU HALT” alarms.
Tighten the 125 VDC Lugs Once, Then Again After 24 Hours
Fine-strand 6 AWG cold-flows under the lug. I torque to 2 N·m, run the rack, then re-torque the next day. Skipping the re-check gives you a brown-out that looks exactly like a dying power supply.
Fine-strand 6 AWG cold-flows under the lug. I torque to 2 N·m, run the rack, then re-torque the next day. Skipping the re-check gives you a brown-out that looks exactly like a dying power supply.
Don’t Swap Fuses Without a Meter
The GMT fuses are 3 A, but the red LED lies—check continuity. Half the time the fuse is good and the real fault is a shorted downstream card. Power down, buzz the rails to ground; anything under 2 Ω means pull the rest of the rack first.
The GMT fuses are 3 A, but the red LED lies—check continuity. Half the time the fuse is good and the real fault is a shorted downstream card. Power down, buzz the rails to ground; anything under 2 Ω means pull the rest of the rack first.
Verify J4 Alarm Loop
The supply reports “power-good” via J4. If you drop in a fresh card and still get “EXPS FAULT,” swap the twisted pair—GE wired it normally-closed, so a broken wire reads bad supply.
The supply reports “power-good” via J4. If you drop in a fresh card and still get “EXPS FAULT,” swap the twisted pair—GE wired it normally-closed, so a broken wire reads bad supply.
GE DS200SDCIG1A
Technical Deep Dive & Overview
The DS200EXPSG1ACB is a half-rack switch-mode pre-regulator. A UC3844 forward converter chops 125 VDC at 100 kHz, drives a custom ferrite transformer, and produces the three secondaries that become +5 V, +15 V, and –15 V. Each secondary has its own LC filter and GMT fuse before it leaves the board. The 5 V rail also feeds a TL431 reference; when that rail sags below 4.8 V the green LED goes out and the red LED pulls the J4 alarm line low, killing the enable to downstream IGBT drivers. No pots, no trim—GE learned early that field techs will “tweak” a supply into oscillation. The ACB revision adds thicker conformal coat and swaps the input caps for 105 °C rated units—cheap insurance against geothermal H₂S.
The DS200EXPSG1ACB is a half-rack switch-mode pre-regulator. A UC3844 forward converter chops 125 VDC at 100 kHz, drives a custom ferrite transformer, and produces the three secondaries that become +5 V, +15 V, and –15 V. Each secondary has its own LC filter and GMT fuse before it leaves the board. The 5 V rail also feeds a TL431 reference; when that rail sags below 4.8 V the green LED goes out and the red LED pulls the J4 alarm line low, killing the enable to downstream IGBT drivers. No pots, no trim—GE learned early that field techs will “tweak” a supply into oscillation. The ACB revision adds thicker conformal coat and swaps the input caps for 105 °C rated units—cheap insurance against geothermal H₂S.
