Description
Key Technical Specifications
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Model Number: IS200EXTBG1AAA
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Manufacturer: General Electric
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Power Rails: M1 & M2 isolated 24 VDC inputs (board derives local 5 V & ±12 V)
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Contact Inputs: 3 opto-isolated, 24 VDC, 2 ms debounce
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Relay Outputs: Relay 41 “close” driver (Form-C, 2 A) for redundant field-breaker control
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Protection: > 130 precision resistors for surge suppression and current limit
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Connectors: 96-pin DIN to VME back-plane, two 20-position pluggable for field contacts
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Isolation: 1500 Vrms contact-to-logic, 500 V channel-to-channel
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Coating: Standard conformal coat for coal/oil mist environments
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Operating Temperature: –20 °C to +70 °C inside exciter cabinet
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Dimensions: Lightweight rectangular PCB, standard 6U VME depth
GE DS3800HLEA1C1B
Field Application & Problem Solved
In a 2000-era EX2100 cabinet the static exciter needs to know if the field breaker is really closed before it ramps volts. The IS200EXTBG1AAA sits in the VME rack, reads three dry-contact inputs (breaker status, field-discharge, manual flashing), and drives Relay 41 to close the field breaker redundantly. When the card fails you lose contact status, the exciter folds back to manual, and you trip on “EXCOMM FAULT”; swap the board, snap the 20-pin plugs back in, and the close logic returns—no re-cal, no firmware flash. You’ll find this PCB in every EX2100 cabinet from 50 MW peakers to 400 MW combined-cycle blocks. Its value is bullet-proof status: the three inputs are opto-isolated, so a shorted field contact can’t pull down the 24 V bus and crash the whole rack.
In a 2000-era EX2100 cabinet the static exciter needs to know if the field breaker is really closed before it ramps volts. The IS200EXTBG1AAA sits in the VME rack, reads three dry-contact inputs (breaker status, field-discharge, manual flashing), and drives Relay 41 to close the field breaker redundantly. When the card fails you lose contact status, the exciter folds back to manual, and you trip on “EXCOMM FAULT”; swap the board, snap the 20-pin plugs back in, and the close logic returns—no re-cal, no firmware flash. You’ll find this PCB in every EX2100 cabinet from 50 MW peakers to 400 MW combined-cycle blocks. Its value is bullet-proof status: the three inputs are opto-isolated, so a shorted field contact can’t pull down the 24 V bus and crash the whole rack.
Installation & Maintenance Pitfalls (Expert Tips)
Contact input reversed—24 V on 5 V pin cooks the opto
The two field headers are keyed alike but pin-outs differ. Land a 125 VDC field contact on the logic side and you blow the opto-coupler—card smells like fish. Meter pin-to-pin before you torque; the silk-screen “CI1/CI2/CI3” legend is your friend.
The two field headers are keyed alike but pin-outs differ. Land a 125 VDC field contact on the logic side and you blow the opto-coupler—card smells like fish. Meter pin-to-pin before you torque; the silk-screen “CI1/CI2/CI3” legend is your friend.
Relay 41 arc—contact welds, breaker stays closed
Relay 41 is only rated 2 A. If the field breaker coil draws > 2 A inductive, the contacts weld and the breaker can’t trip on fault. Always add an interposing relay or check the coil spec—otherwise you’ll be explaining to the insurance guy why the generator fed a fault for 30 s.
Relay 41 is only rated 2 A. If the field breaker coil draws > 2 A inductive, the contacts weld and the breaker can’t trip on fault. Always add an interposing relay or check the coil spec—otherwise you’ll be explaining to the insurance guy why the generator fed a fault for 30 s.
Conformal coat cracked—salt fog kills the pull-up
The board is coated, but the 20-pin edge is masked. If the coat cracks, salt bridges the 5 V pull-up and you get false “contact closed.” Scrape the salt, hit the edge with 2100-FTG, and re-coat—problem gone for another decade.
The board is coated, but the 20-pin edge is masked. If the coat cracks, salt bridges the 5 V pull-up and you get false “contact closed.” Scrape the salt, hit the edge with 2100-FTG, and re-coat—problem gone for another decade.
Missing shoulder washers—card arcs to rack
The four corner holes are through-plated. Forget the fiber washers and the card edge sits 0.5 mm proud; 125 V field voltage finds the rack paint, arcs, and blows a hole in the ground plane. Use the original GE shoulder washers—torque to 8 in-lb, no more.
The four corner holes are through-plated. Forget the fiber washers and the card edge sits 0.5 mm proud; 125 V field voltage finds the rack paint, arcs, and blows a hole in the ground plane. Use the original GE shoulder washers—torque to 8 in-lb, no more.
Technical Deep Dive & Overview
IS200EXTBG1AAA is basically a smart contact input card frozen in 1999 silicon. Three opto-couplers read field-breaker status, a 74LS374 latch presents the data to the VME bus, and a Form-C relay gives the exciter a hard-wired path to close the field breaker redundantly. Because the card carries both logic and contact power, you can swap it hot and the exciter never knows—just kill the 125 VDC field supply first or you’ll arc-weld the 20-pin plugs. Treat the contact inputs like instrumentation loops and the board will keep the field breaker closing for another thirty years .
IS200EXTBG1AAA is basically a smart contact input card frozen in 1999 silicon. Three opto-couplers read field-breaker status, a 74LS374 latch presents the data to the VME bus, and a Form-C relay gives the exciter a hard-wired path to close the field breaker redundantly. Because the card carries both logic and contact power, you can swap it hot and the exciter never knows—just kill the 125 VDC field supply first or you’ll arc-weld the 20-pin plugs. Treat the contact inputs like instrumentation loops and the board will keep the field breaker closing for another thirty years .
