Yokogawa NFAR181-S50 Temperature Input Module

Overview

The NFAR181-S50 is a multi-channel temperature measurement input module developed by Yokogawa for use in ProSafe-RS safety-instrumented systems and high-reliability control platforms. It is designed to acquire precise temperature data from RTD and thermocouple sensors while maintaining strict electrical isolation between channels, ensuring dependable operation in electrically noisy and safety-critical environments.

This module is commonly deployed in continuous-process industries where temperature integrity directly impacts process safety, equipment protection, and regulatory compliance.

Functional Characteristics

The NFAR181-S50 provides twelve individually isolated input channels, allowing simultaneous measurement of multiple temperature points without signal interference. Each channel supports configurable sensor types, enabling flexible field wiring and simplified spare-parts management across mixed RTD and thermocouple installations.

Integrated cold-junction compensation and digital linearization ensure stable and repeatable measurements across wide temperature ranges. The module is optimized for fast data refresh, supporting control and safety logic that requires timely temperature feedback.

Supported Sensor Inputs

RTD Measurement

• Pt100 RTD, 3-wire configuration

• JPt100 RTD, 3-wire configuration

• Measurement range from −200 °C to +800 °C

• Typical accuracy up to ±0.15 °C

• Internal lead-wire resistance compensation

Thermocouple Measurement

• Compatible thermocouple types include J, K, E, T, B, R, and S

• Supports additional MIL-standard thermocouple variants

• Built-in cold-junction compensation

• Automatic linearization per selected thermocouple type

Performance Specifications

• Input channels: 12, fully isolated

• Channel-to-channel isolation: Supported

• Channel-to-system isolation: Supported

• Data update interval: Approximately 1 second

• Long-term measurement stability optimized for continuous operation

• High resistance to electromagnetic and conducted noise

Mechanical and Environmental Data

• Module form factor: Compact I/O card for Yokogawa safety systems

• Dimensions: 130 × 107.5 × 32.8 mm

• Weight: 0.3 kg

• Designed for control room and field-mounted safety cabinets

System Compatibility

The NFAR181-S50 is designed for seamless integration with Yokogawa ProSafe-RS safety controllers and related I/O subsystems. Configuration and diagnostics are performed through Yokogawa engineering tools, allowing sensor selection, range assignment, and fault monitoring at the system level.

Typical Applications

• Safety-instrumented temperature monitoring

• Burner and furnace protection systems

• Reactor and vessel temperature supervision

• Turbine and auxiliary equipment monitoring

• High-integrity shutdown and alarm systems

Frequently Asked Questions

Can RTD and thermocouple sensors be mixed on the same module?
Yes. Each channel can be configured independently, allowing RTD and thermocouple inputs to coexist on a single NFAR181-S50 module.

Is the module suitable for SIL-rated systems?
Yes. The module is intended for use in Yokogawa ProSafe-RS safety systems and meets the reliability requirements typical of SIL-based architectures when used in approved configurations.

Does the module require external cold-junction compensation hardware?
No. Cold-junction compensation is integrated into the module for thermocouple measurements.