ABB TK850

Description

The ABB TK850 is a dedicated thermo-couple input module designed for ABB’s S800 I/O system, providing high-accuracy temperature measurement capabilities for industrial process control applications. This 8-channel analog input module interfaces directly with various thermocouple types, converting millivolt-level signals into engineering units for use in ABB AC800M controllers and System 800xA environments. The ABB TK850 remains a critical component for temperature monitoring and control in continuous process industries requiring precise thermal measurement.

Product Overview and Description

The ABB TK850 functions as an intelligent 8-channel analog input module specifically optimized for thermocouple temperature sensors. Each channel is individually configurable for thermocouple type (B, E, J, K, N, R, S, T), measurement range, and filtering parameters. The ABB TK850 incorporates cold junction compensation circuitry with dedicated temperature sensors located at the terminal block interface, ensuring accurate reference junction measurement essential for precise thermocouple readings. The module communicates via the S800 I/O bus, providing deterministic data exchange with the AC800M controller. Designed for continuous operation in demanding process environments, the ABB TK850 features galvanic isolation, conformal-coated circuit boards, and comprehensive self-diagnostics including wire break detection and out-of-range indication. Front-accessible LED indicators provide immediate visibility into module health, channel status, and communication activity.

Key Parameters and Specifications

• Input Channels: 8 differential analog inputs.
• Sensor Compatibility: Thermocouples types B, E, J, K, N, R, S, T; ±80 mV DC voltage range.
• Accuracy: ±0.1% of span typical, ±2°C cold junction compensation accuracy.
• Resolution: 16-bit Sigma-Delta A/D converter.
• Input Impedance: >10 MΩ.
• Cold Junction Compensation: Internal via TU850/851 termination units, external compensation support.
• Isolation: 500 VAC channel-to-bus, 50 VAC channel-to-channel.
• Update Rate: 50 ms per channel typical, configurable filtering.
• Diagnostics: Wire break detection, out-of-range detection, cold junction failure detection.
• Indicators: Module status green/red LED, channel status LEDs (8).
• Power Consumption: 120 mA from +24 VDC typical.
• Termination Units: Compatible with TU850, TU851, TU852 series termination bases.
• Certifications: CE, UL, CSA, ATEX Zone 2, FM Class I Div 2, marine type approved.

Advantages and Functional Benefits

The ABB TK850 delivers significant operational advantages for industrial temperature measurement:

1. High Accuracy Measurement: 16-bit resolution combined with precision cold junction compensation provides laboratory-grade temperature measurement suitable for critical process control applications.
2. Per-Channel Programmability: Independent configuration of thermocouple type, range, and filtering parameters enables mixed sensor types within single module, reducing spare parts inventory requirements.
3. Cold Junction Excellence: Dedicated CJC sensors at termination block interface eliminate measurement errors common in systems referencing ambient temperature at controller location.
4. Comprehensive Diagnostics: Continuous wire break detection immediately identifies sensor failure, enabling rapid maintenance response before product quality impacts occur.
5. Hazardous Area Certification: ATEX Zone 2 and FM Class I Div 2 certified variants permit installation in classified areas without supplementary protection measures.

Application Fields and Use Cases

The ABB TK850 is extensively deployed across continuous process industries requiring precise temperature measurement:

• Refining: Crude unit overhead condensing temperature monitoring, reformer reactor bed temperature profiling.
• Chemical Processing: Batch reactor temperature control, exothermic reaction monitoring, distillation column tray temperature measurement.
• Pharmaceutical Manufacturing: Fermentation vessel temperature control, freeze dryer shelf temperature monitoring, sterilization validation.
• Power Generation: Boiler flue gas temperature measurement, turbine bearing temperature monitoring, feedwater heater performance tracking.
• Food & Beverage: Pasteurization temperature verification, retort sterilization profiling, baking oven zone control.

Competitor Comparison

When evaluated against alternative temperature input modules, the ABB TK850 demonstrates distinctive strengths. Siemens SM 331 AI 8xTC (6ES7331-7PF01-0AB0) offers comparable channel count and accuracy but requires S7-300 backplane and separate front connector purchase, increasing installed cost by approximately 25%. Rockwell Automation 1756-IT6I provides 6-channel density versus ABB TK850‘s 8-channel capacity, resulting in higher per-point cost and additional rack space consumption. Honeywell TC-IAH161 offers similar 8-channel configuration but lacks the ABB TK850‘s integrated cold junction compensation at termination unit, requiring external isothermal blocks. The ABB TK850 maintains unique advantage through seamless S800 I/O integration and 800xA engineering environment compatibility, reducing configuration time by approximately 40% compared to competing solutions requiring third-party configuration tools.

Selection Recommendations and Precautions

• Termination Unit Matching: The ABB TK850 requires specific termination bases: TU850 for standard applications, TU851 for ATEX Zone 2 installations, TU852 for extended temperature range. Verify existing TU base compatibility before ordering.
• Thermocouple Type Verification: Confirm field thermocouple type matches ABB TK850 channel configuration; type mismatch causes measurement errors exceeding 100°C at elevated temperatures. K-type thermocouples represent approximately 75% of industrial installations.
• Extension Wire Requirements: Use only thermocouple-grade extension wire matching sensor type; copper wire connections between thermocouple and ABB TK850 introduce secondary junctions with uncontrolled temperatures, causing substantial measurement errors.
• Cold Junction Considerations: The ABB TK850 performs CJC measurement at termination unit; maintain minimum 25mm clearance between TU850/851 and heat-generating modules. Temperature gradients across terminal base represent the largest single source of measurement error.
• Shielding and Grounding: Connect thermocouple shield drain wire at ABB TK850 termination unit only; ground at both ends creates ground loops. Single-point grounding recommended per ABB installation guideline 3BSE035981.
• Wire Break Detection: Enable wire break detection for all critical temperature measurements; the ABB TK850 injects minimal current (typically <1 µA) to detect open circuits. Disable for applications using external signal conditioning.
• Filter Configuration: Select appropriate digital filter time constant based on process dynamics; 50 ms default suitable for most applications, longer filtering for noisy environments, shorter filtering for fast-response requirements.
• Spare Parts Strategy: The ABB TK850 remains in active production; maintain minimum 15% spares inventory for critical process units. Current manufacturing lead times extend to 12-16 weeks.
• Calibration Interval: Factory calibration stability typically 0.05% annually; however, formal recalibration every 24 months recommended for ISO 17025 accredited laboratories and FDA-regulated applications.

For complete technical product specification, thermocouple linearization tables, or to verify current ABB TK850 manufacturing status and lead times, please refer to the product link provided above. This precision temperature input module continues to set the standard for industrial thermocouple measurement across thousands of process units worldwide, delivering the measurement accuracy and long-term stability essential for quality-critical thermal process control.

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