Honeywell STT850 temperature transmitter

Honeywell STT850 temperature transmitter

Product Overview

The Honeywell STT850 is a high-performance temperature transmitter engineered for demanding industrial automation and process control environments. As a core component of Honeywell’s SmartLine family, the STT850 delivers exceptional measurement accuracy and long-term stability across wide-ranging process and ambient temperature conditions. The total installed accuracy level of the transmitter allows the STT850 to replace virtually any competitive transmitter available on the market today.-1-36

The STT850 is built on the industry’s first modular temperature measurement platform, offering robust performance throughout the entire plant lifecycle—from construction and commissioning to daily operations and maintenance.-37Fully tested and compliant with Honeywell Experion® PKS standards, the STT850 provides the highest level of compatibility assurance and seamless integration capabilities with existing control system infrastructure.-3

Key Technical Specifications

Measurement Capabilities:

Differential – Measure temperature difference between two sensors

Averaging – Average temperature across multiple sensing points

Redundant – Dual-sensor configuration for critical applications

Split Range – Multiple measurement ranges on a single transmitter

Performance Characteristics

Accuracy & Stability

The STT850 delivers digital accuracy up to ±0.1°C for RTD inputs, combined with output D/A accuracy of ±0.005% of span for Pt100 sensors.-1-11The transmitter maintains long-term stability of ±0.01% of URL per year sustained over a ten-year period, reducing calibration frequency and maintenance costs.-1

Response Time

With update times of 125 ms for single-input configurations and 250 ms for dual-input models, the STT850 provides near real-time temperature data to control systems, supporting rapid process adjustments and minimizing control loop latency.-3-5

Sensor Matching

The STT850 includes a sensor matching facility that achieves higher overall accuracy. Direct entry of Callendar-Van Dusen coefficients (R0, α, δ, β) for calibrated RTD sensors is supported, enabling the transmitter to compensate for individual sensor variations and achieve measurement precision beyond standard tolerance levels.-1-5

Environmental & Durability Specifications

Protection Ratings

The STT850 is available with IP66, IP67, and NEMA 4X protection grades, ensuring reliable operation in harsh industrial environments exposed to moisture, dust, and corrosive agents. The dual compartment housing design separates electronics from wiring terminals for enhanced reliability.-5-36

Hazardous Area Certifications

The STT850 carries comprehensive global hazardous location approvals:

Explosion-proof and Intrinsic Safety: FM, CSA, ATEX, IECEx, NEPSI, KOSHA, INMETRO, SAEx, EAC, CCoE

Marine Approvals: ABS, DNV, LR, BV

EMC Compliance: EN 61326-1, EN 61326-3-1

SIL Compliance: Full compliance with SIL 2/3 requirements per IEC 61508-11

Diagnostic Capabilities

Comprehensive on-board transmitter and sensor diagnostics

Sensor break detection (supports Namur 89 wire break)

Namur 107 extended diagnostics

Sensor health trend visualization through advanced display

Built-in galvanic isolation-5-36

Display Options

The modular STT850 accommodates two display choices:

Basic Alphanumeric LCD: Two lines, 16 characters, multiple unit display (°C, °F, °R, Kelvin, mV, Ohm)

Advanced Graphics LCD: Up to eight display screens with trend graph capability, multi-language support (EN, GE, FR, IT, SP, RU, TR, CN, JP)-36-14

Applications & Industries

The STT850 is ideally suited for process manufacturers, OEMs, and EPC contractors requiring high-precision temperature measurement with SIL-rated safety integrity.

Typical Applications:

Oil & Gas: Refinery process temperature monitoring, pipeline temperature control

Chemical Processing: Reactor temperature management, exothermic reaction monitoring

Power Generation: Boiler feedwater temperature, steam temperature control, turbine inlet monitoring

Pharmaceuticals: Sterilization validation, bioreactor temperature measurement

Food & Beverage: Pasteurization, cooking process control, cold storage monitoring

Pulp & Paper: Digester temperature control, drying cylinder monitoring

HVAC: Building automation and environmental control

Compatible Systems: Honeywell Experion PKS, any 4-20 mA loop-powered input cards, DCS, PLC, SCADA systems

Ordering & Configuration Information

The STT850 temperature transmitter is a comp