DS200CTBAG1ADD | GE Mark V Board | Thermocouple

Description

Product Introduction

The GE DS200CTBAG1ADD is a thermocouple input module for the Mark V Speedtronic turbine control system. It is designed for high-temperature measurement (e.g., gas turbine inlet, combustion monitoring, and exhaust upstream of EGT probes). This module adds extended range calibration and high-ambient-temperature components to the CTBAG1A platform.

Core advantage: The ADD revision is factory-calibrated for Type K thermocouples up to 1250°C (standard CTBAG1A is calibrated to 1000°C). It also uses high-temperature op-amps (125°C rated) and capacitors (105°C) for operation in turbine enclosures up to 65°C ambient. Field data from gas turbine combustion monitoring shows the ADD board maintains ±1.5°C accuracy at 1200°C – standard boards have ±5°C error above 1000°C due to ADC nonlinearity.

Key Technical Specifications

Key Selling Points & Differentiators

• Extended range to 1250°C (Type K) – Standard CTBA boards saturate at 1000°C. ADD calibrated for high-temperature gas turbine monitoring. Covers combustion outlet and turbine inlet.
• High-ambient operation to 65°C – Standard boards rated 0-55°C. ADD uses high-temp components for turbine enclosures without air conditioning.
• Specialized linearization for Type K above 1000°C – Uses 4th-order polynomial (NIST ITS-90 extended range). Standard linearization error increases above 1000°C.
• Type B thermocouple support (200-1700°C) – For very high-temperature applications (pyrometer backup, gasifier monitoring).
• Same 16-channel density as CTBAG1A – No channel count reduction for high-temp features.
• Live tested with Type K at 1200°C – We heat a Type K TC to 1200°C in a calibration furnace (NIST traceable) and verify board reading within ±1.5°C.
• 30-day warranty with cross-ship – High-temp calibration drift or component failure? We send replacement same day.

Frequently Asked Questions (FAQ)

Q: What is the difference between DS200CTBAG1A and DS200CTBAG1ADD?
A: Temperature range and ambient rating. CTBAG1A: Type K up to 1000°C, ambient 0-55°C. CTBAG1ADD: Type K up to 1250°C, ambient 0-65°C, high-temp components. The ADD is for high-temperature turbine monitoring (combustion, turbine inlet). For standard EGT monitoring (exhaust, <1000°C), CTBAG1A is sufficient.

Q: Can I use the ADD board for standard EGT monitoring (exhaust, <1000°C)?
A: Yes – it works fine. Accuracy is similar to CTBAG1A (±1.0°C). You are paying extra for range you do not need. For cost-sensitive projects, use CTBAG1A. For turbines with high exhaust temperature (Frame 9, H-class), ADD is recommended.

Q: How do you test the high-temperature calibration on refurbished boards?
A: We use a Type K thermocouple in a calibration furnace (NIST traceable) at 500°C, 800°C, 1000°C, 1100°C, 1200°C, and 1250°C. The board must read within ±1.5°C at 1200°C and ±2.0°C at 1250°C. We also test Type R at 1600°C (special order). About 12% of incoming ADD boards fail high-temp testing – linearization table corrupted or ADC nonlinearity. Those are repaired (re-flash linearization table) or scrapped.

Q: I see an ADD board with a purple sticker near the terminal block. What does that mean?
A: The purple sticker indicates the board received an additional “furnace soak” test at 1250°C for 100 hours continuous. The board and TC must maintain accuracy within ±2.0°C. Standard boards are tested at 1200°C for 1 hour only. Purple-sticker boards are for continuous high-temperature monitoring (e.g., gasifier, incinerator). We charge an extra $50 for purple-sticker boards.

Q: My ADD board reads 5°C low at 1200°C on channel 3 only. Other channels are fine. What failed?
A: The ADC input mux for channel 3 has temperature-dependent nonlinearity. This is common on boards with high usage at elevated temperatures. The mux (ADG408) ages and its on-resistance changes with temperature. Repair cost is $185. We replace the input mux and recalibrate all channels. Turnaround is 7 days.

Q: Does the ADD board support Type B thermocouples?
A: Yes – Type B (Pt-30% Rh vs Pt-6% Rh) from 200°C to 1700°C. Below 200°C, Type B has very low output (0.1 mV) – readings will be inaccurate. For ambient temperature measurement, use Type K or T. The ADD is optimized for high-temperature B (1000-1700°C). Accuracy at 1500°C is ±2.0°C.

Q: How do I identify a counterfeit DS200CTBAG1ADD?
A: Genuine boards have “CTBAG1ADD” printed on the edge connector label with a “HT” (high temp) stamp. The ADC chip is Analog Devices AD7732 with extended temperature grade (-40 to 105°C). Counterfeits use commercial grade AD7732 (0-70°C) or unmarked chips. Also check the op-amps: genuine uses AD8512 (125°C rated). Fakes use LM358 (70°C). We photograph the ADC and op-amp date codes on every board.

Q: What is the maximum continuous temperature for the ADD board in a turbine enclosure?
A: 65°C ambient. At 65°C, the board’s components run at 85-90°C (still within ratings). For enclosures above 65°C, do not use this board. The high-temp capacitors are rated 105°C, but the CJC thermistor accuracy degrades above 65°C (±2°C at 75°C). Install cabinet cooling. For extreme environments (Middle East summer), add air conditioning.

Q: Can the ADD board be used with extension grade thermocouple wire at high temperatures?
A: Yes – but the extension wire must be rated for the ambient temperature at the board. Standard TC extension wire (PVC insulation) is rated 0-75°C. At board ambient 65°C, PVC is near its limit. Use high-temperature extension wire (Teflon or fiberglass insulation) rated 0-200°C. We sell high-temp extension cable for $2.50 per foot.

Q: Does the ADD board support open thermocouple detection at high temperatures?
A: Yes – same circuit as CTBAG1A. However, at temperatures above 1200°C, a failing TC may read low (drift) before going completely open. The open detection circuit will trigger when the TC breaks. For predictive maintenance, trend the TC resistance (we provide a resistance measurement procedure). ADD boards measure TC resistance through the same input circuit.

Q: What is the expected life of the high-temp capacitors at 65°C ambient?
A: Electrolytic capacitors are rated for 5,000 hours at 105°C. At 65°C, life doubles for every 10°C reduction (rule of thumb). 105°C to 65°C is 40°C reduction = 2^4 = 16x life extension. 5,000 hrs x 16 = 80,000 hours (9.1 years) continuous operation. Field data shows 8-10 years typical. For 24/7 turbines, replace capacitors at 8 years as preventive maintenance.

Q: Do you offer a version with conformal coating and high-temperature calibration?
A: Yes – special order DS200CTBAG1ADD-CC (silicone coated, high-temp calibrated). Lead time is 14-21 days. Cost adds $75. For refineries with high-temp turbines (cogeneration), we recommend coated ADD. For offshore high-temp (limited), acrylic coating (ABB) may be sufficient. Specify “refinery” or “offshore” when ordering to select correct coating.

Q: What is the warm-up time for the ADD board to achieve specified accuracy at 1250°C?
A: The board reaches 90% of final accuracy within 5 minutes. Full accuracy (no drift) requires 30 minutes for the ADC and reference to thermally stabilize. For critical high-temperature monitoring (e.g., turbine protection), we recommend a 30-minute warm-up before enabling alarms based on >1000°C readings. For standard EGT monitoring (<1000°C), warm-up is 10 minutes.

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