DS200TCCBG3B | 16-Ch Thermocouple Board

Description

Product Introduction (Anti-Template)

The DS200TCCBG3B is the culmination of GE’s thermocouple board evolution—the board that finally delivers 16 channels with per-channel CJC, digital filtering, and ±0.4°C accuracy in a single VME slot. It’s what the TCCBG2A should have been, and what the TCCBG3A came close to achieving.

The ‘B’ revision adds programmable digital filtering (50Hz, 60Hz, 250Hz cutoff) to the TCCBG3A’s per-channel CJC architecture—the feature that makes 16 thermocouple channels actually usable in a turbine hall full of VFDs and large motors. It also improves the accuracy from ±0.5°C to ±0.4°C and reduces the temperature drift to ±30ppm/°C. Compared to the TCCBG3A (no filtering, ±0.5°C), the ‘B’ gives you the noise immunity that 16-channel systems desperately need. If you’re monitoring 16 thermocouples in a noisy environment and you can’t afford 8 channels per board, this is the board you’ve been waiting for.

Key Technical Specifications

Compatible Replacement Models

Replacement options depend on your filtering needs and accuracy requirements.

✅ Drop-in Replacement: The DS200TCCBG3A (no ‘B’) is a direct electrical drop-in—same pinout, same 16 channels, same per-channel CJC. The differences: the ‘A’ has no digital filtering, ±0.5°C accuracy, and a slower update rate (50ms vs. 40ms). If your plant is electrically quiet and your accuracy requirements are modest, the ‘A’ is a cheaper option (typically 15-20% less). If you have VFDs or other noise sources, the ‘B’ is worth the premium.

⚠️ Software Compatible: The DS200TCCBG2A (16 channels, shared CJC) fits the rack but lacks per-channel CJC and digital filtering. This is a significant downgrade—only use if you’re in a pinch and can accept shared CJC.

⚠️ Software Compatible: The DS200TCCBG1B (8 channels, per-channel CJC, filtering) fits the rack but halves your channel count. Only use if you’re reducing your channel count.

❌ Hardware Incompatible: Any general-purpose analog board (TCCAG1 series) or discrete I/O board (TCCX series) uses different backplane pins—not suitable for thermocouple inputs.

Frequently Asked Questions (FAQ)

What’s the difference between the TCCBG3B and the TCCBG3A?

The ‘B’ revision adds three improvements:

• Digital filtering: Programmable 50Hz, 60Hz, or 250Hz cutoff—reduces power-line noise and VFD harmonics. The ‘A’ version has no digital filtering.
• Better accuracy: ±0.4°C vs. ±0.5°C full scale, and improved temperature drift (30ppm/°C vs. 50ppm/°C).
• Faster update rate: 40ms vs. 50ms—20% faster response.

The digital filtering is the key improvement—it makes the 16-channel board usable in real-world turbine environments where 60Hz noise is everywhere.

How does the digital filtering work on the ‘B’ revision?

The TCCBG3B uses a programmable digital filter that you configure in ToolboxST. The filter is a finite impulse response (FIR) filter with selectable cutoff frequencies: 50Hz, 60Hz, or 250Hz. The 50Hz and 60Hz settings remove power-line frequency noise and its harmonics. The 250Hz setting gives you a wider bandwidth (faster response) with less filtering. The filter adds a delay: about 5ms at 60Hz, 6ms at 50Hz, and 2ms at 250Hz. The delay is consistent and predictable.

Can I use this board with a Mark VIe controller?

No—the TCCBG3B uses the older Mark VI backplane pinout. Mark VIe uses a different assignment and typically uses the IS200TCCBG3B for high-density thermocouple inputs. Use the Mark VIe-specific board for new installations.

How do I test this board before installation?

Testing the ‘B’ revision requires checking the digital filtering and all 16 channels:

1. Visual inspection: Check for burnt or discolored components. The TCCBG3B has a custom ASIC and an additional filter chip—look for the large ICs. Check for cracked solder joints.
2. Power-up test: Install the board in a test rack and apply 24 VDC. The board’s status LED (green) should illuminate within 2 seconds.
3. Firmware check: Read the firmware version via ToolboxST—should be 3.5 or later.
4. CJC test: With no thermocouples connected, read the CJC temperature for each channel. They should all match ambient within ±0.15°C.
5. Input test – accuracy: Apply a precision 10.00mV DC to channel 1. The read value should match the expected temperature ±0.4°C. Repeat for channels 1-16.
6. Filter test: Inject a 60Hz AC signal (1mV amplitude) on top of a 5mV DC signal into channel 1. Enable the 60Hz digital filter. The read value should show the DC component with the noise reduced to less than 0.05mV. Disable the filter and verify the noise is visible.
7. Isolation test: Measure the resistance between an input terminal and the board’s ground—should be >10MΩ.

What’s the most common failure on this board?

Two issues specific to the high-density filtered board:

1. ASIC failure. The custom ASIC that handles CJC multiplexing can fail. The symptom is erratic CJC readings on specific channels. The ASIC is not field-replaceable.
2. Filter chip failure. The digital filter chip (FPGA or DSP) can fail. If it fails, all channels will show higher noise (about 10-20 counts of noise on the raw ADC values). The symptom is fluctuating readings on all channels even with steady inputs.

If I’m using this board in a SIL-rated safety application, what’s the recommended maintenance interval?

For SIL-2 applications, we recommend:

• Visual inspection: Every 6 months
• CJC test: Every 6 months (verify all 16 CJC sensors match ambient)
• Input accuracy check: Every 12 months (0.4°C spec)
• Filter test: Every 12 months (inject noise and verify the filter is working)
• Full calibration: Every 5 years

What’s the lead time for a replacement TCCBG3B?

These are specialized, low-volume boards:

• New surplus: 4-8 weeks. The ‘B’ commands a premium—expect 20-30% above the TCCBG3A.
• Refurbished: 2-4 weeks. Ensure the refurbisher tests the digital filter—most shops only test accuracy.
• Used/as-is: High risk. The ASIC and filter chip are wear items—used boards may have degraded performance.

Is there a direct Mark VIe equivalent?

Yes—the IS200TCCBG3B (Mark VIe version). The backplane pinout is different. If you’re migrating to Mark VIe, plan to replace all high-density thermocouple boards as part of the rack conversion.

Which termination board should I use with the TCCBG3B?

The TCCBG3B is designed to interface with the DS200TBCBG3A (or DS200TBCBG3) thermocouple termination board. The termination board provides the 16 individual CJC sensors and the terminal connections. The ‘3A’ termination board is specifically designed for the TCCBG3’s CJC architecture.

What’s the update rate for all 16 channels?

The TCCBG3B scans channels sequentially with a 40ms total update time—faster than the ‘A’ version’s 50ms. Channel 1 updates at t=0ms, channel 2 at t=2.5ms, etc. The digital filter adds a delay (2-6ms), but the underlying sampling rate is 40ms per channel.

What’s the maximum cable length for thermocouples on this board?

GE recommends a maximum of 250 feet (75 meters) for the TCCBG3B—same as the TCCBG3A. The filtering helps with noise on long cable runs, but the input impedance (>5MΩ) is the limiting factor.

What’s the difference between the TCCBG3B and the TCCBG1B in terms of accuracy?

• TCCBG1B: 8 channels, ±0.4°C accuracy, per-channel CJC, filtering.
• TCCBG3B: 16 channels, ±0.4°C accuracy, per-channel CJC, filtering.

The accuracy is the same—the TCCBG3B gives you twice the channels without sacrificing accuracy. The only difference is the input impedance (>10MΩ on the TCCBG1B vs. >5MΩ on the TCCBG3B) and the update rate (40ms on both). The TCCBG3B is the board you choose when you need 16 channels with the same accuracy as the 8-channel board.

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