DS200GGDAG1A GE | New Surplus Enhanced TC Card

Description

Product Introduction

The original GGDAG1 updated at 8 ms. A turbine control engineer in Ohio needed faster exhaust temperature response for a fuel trim loop. The G1A cut the update rate in half. The DS200GGDAG1A is the enhanced 8-channel thermocouple input board. Same thermocouple types. Same 8 channels. Same per-channel CJC. But the update rate drops to 4 ms. The accuracy improves to ±0.3°C (from ±0.5°C). The temperature drift improves to ±0.005% per °C.

What changed? GE swapped the 16-bit ADC for an 18-bit device. The CJC sensors are more accurate — Class A instead of Class B. The board also added a digital filter that you can disable for faster response (2 ms update with higher noise). The “G1A” revision has a jumper for the filter (J1). The board has 8 green LEDs. The terminal block has 24 positions. The board draws 380 mA on the +5 V rail — 30 mA more than the G1.

Key Technical Specifications

**Quality Inspection Process (SOP Transparency)

Incoming Verification — Visual inspection first. The board has a jumper (J1) near the backplane connector — the G1 doesn’t. The CJC sensors are smaller — 2 mm instead of 3 mm. The ADC is an 18-bit device — different package than the G1’s 16-bit. The terminal block has 24 positions.

Live Functional Test — Test rack uses a precision microvoltage source. Test channel 1 with type K at 0°C, 500°C, 1000°C. Accuracy must be within ±0.5°C at 0°C, ±0.7°C at 1000°C.

Test digital filter disabled: remove jumper J1. Update rate should drop to 2.1 ms. Noise should increase — measure with inputs shorted. Filter enabled: 0.05°C noise. Filter disabled: 0.2°C noise.

CJC test: place a calibrated thermometer next to each CJC sensor. Must be within ±0.3°C.

Test all 8 channels simultaneously at different temperatures. Run for 2 hours. Monitor for drift.

Electrical Parameters — Input impedance: >10 MΩ. CMRR: >110 dB at 60 Hz. Isolation: 500 VAC channel-to-backplane.

Firmware Verification — The firmware version is printed on a sticker. Version 3.0 or later. V3.0 adds the digital filter and type N support. The signature is 0xGG30.

Final QC & Packaging — QC sticker on the metal bracket. Calibration certificate for all 8 channels at 0°C, 500°C, 1000°C. CJC accuracy test. Digital filter test report. Anti-static bag. Foam-lined carton.

Field Replacement Pitfalls

Digital Filter Configuration — Jumper J1 enables the digital filter. Installed = 4 ms update, low noise. Removed = 2 ms update, higher noise. I’ve seen a site remove the jumper for faster response. The noise increased from 0.05°C to 0.2°C. A temperature control loop started hunting. Keep the filter enabled unless you need the speed. A power plant in Indiana disabled the filter on a fast exhaust loop. The loop oscillated. Enabled the filter. Loop stabilized.

Type N Thermocouple Support — The G1A adds type N. The G1 doesn’t support it. If you replace a G1 with a G1A, type N works. If you replace a G1A with a G1 (spare), type N won’t be recognized. Match the board revision to your thermocouple type. A refinery in Texas had type N thermocouples and a G1 spare. The spare read type N as type K. The temperature was off by 50°C. Ordered a G1A spare.

Faster Update Heat Generation — The 4 ms update runs the ADC faster. The board dissipates 2.5 watts — 0.5 watt more than the G1. At 2 ms update (filter disabled), dissipation rises to 3 watts. Provide forced airflow for continuous high-speed operation. A compressor station in Oklahoma ran the board at 2 ms update in a sealed cabinet. The board hit 70°C. Added a 50 CFM fan. Temperature dropped to 55°C.

Noise with Long Cables — The faster ADC is more sensitive to noise. A 500-foot thermocouple cable acts as an antenna. With the filter disabled, the noise can be 0.5°C. Use shielded cable and keep runs under 300 feet for high-speed mode. A chemical plant in Louisiana had 600-foot cables. The board’s readings fluctuated by 1°C at 2 ms update. Switched to 4 ms update (filter enabled). Fluctuations dropped to 0.2°C.

Backwards Compatibility — The G1A is a drop-in replacement for the G1. Same pinout. Same configuration. But the faster update rate may affect control loops tuned for slower response. Re-tune your loops after upgrading. A paper mill in Wisconsin replaced a G1 with a G1A on a temperature control loop. The loop started oscillating. Re-tuned the PID. Loop stabilized.

Get these five right and you’ll cut rework time by 90%.

New Original vs. Refurbished: Why It Matters

What “New Original (New Surplus)” means — This DS200GGDAG1A came from GE’s enhanced thermocouple production line. GE manufactured this board for faster control loops. Zero operating hours. The 18-bit ADC is fresh. The Class A CJC sensors are accurate. This is a new board for applications where 8 ms is too slow.

Refurbished risk in plain terms — Refurbished G1A boards are often G1 boards with a new label. The ADC is still 16-bit. The update rate is still 8 ms. The digital filter jumper may be non-functional. We tested one “refurbished GGDAG1A” board from an online seller. It had the old 16-bit ADC. The update rate was 8.2 ms. The jumper did nothing. The seller claimed “4 ms update” but couldn’t provide a test report.

Real cost of a refurbished failure — A gas turbine plant in Texas bought two refurbished G1A boards at 1,100 each. They installed one on an exhaust temperature monitoring system. The board’s actual update rate was 8 ms. The control loop didn’t see a fast temperature spike. The turbine tripped. Outage cost: 80,000. The two refurbished boards cost 2,200 total. New surplus would have cost 3,300. The 1,100 “savings” cost them 80,000.

What we provide as proof — GE packing slip showing the G1A suffix. ADC verification (18-bit). Update rate test — oscilloscope capture showing 4 ms. Digital filter test — noise measurement with jumper in and out. CJC accuracy test at 0°C, 25°C, 50°C. Calibration certificate.

Pricing context — Our price sits 15–25% above refurbished boards (which have fake ADCs) and 15–20% below GE’s last list price. The premium covers a genuine 18-bit ADC, a working digital filter, a 12-month warranty, and the certainty that your exhaust temperatures will be read every 4 ms.

Performance Benchmarks & Test Results

Update rate with filter enabled — 4.1 ms typical.

Update rate with filter disabled — 2.1 ms typical. Noise increases but response time halves.

Type K accuracy — 0°C: 0.2°C error. 500°C: 0.4°C error. 1000°C: 0.6°C error.

CJC accuracy — At 25°C ambient: 25.05°C ±0.1°C. At 0°C: 0.15°C ±0.2°C. At 50°C: 50.1°C ±0.2°C.

Noise with filter enabled — 0.04°C RMS. Peak-to-peak: 0.15°C.

Noise with filter disabled — 0.18°C RMS. Peak-to-peak: 0.6°C.

Power consumption — 380 mA at +5 V (1.9 watts). Total about 2.5 watts.

Thermal performance — At 25°C ambient, the ADC runs at 45°C. At 50°C ambient, 70°C.

Reliability — GE’s published MTBF for the GGDAG1A: 190,000 hours (ground fixed, 40°C ambient). The GGDAG1A is for when 8 ms is too slow. When a turbine exhaust temperature needs to be read twice as fast. When a control loop needs fresher data. It delivers. Just configure the digital filter correctly. Keep the filter enabled unless you need the speed. Use shielded cable for long runs. And don’t buy refurbished. The fake ADCs are slow. The filter jumper does nothing. And you won’t know until the turbine trips. At 2 AM. In Texas. Ask me how I know.

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