NFAR181-S00

The Yokogawa NFAR181-S00/R8S0 is a 12-channel isolated RTD input module designed to acquire resistance temperature signals for industrial process monitoring. It belongs to the FCN/FCJ I/O module range. The NFAR181 series provides isolated temperature measurement inputs, while the /R8S00 option identifies a pressure-clamp terminal block configuration for RTD field wiring.

RTD Input Configuration

The module accepts resistance signals from the following three-wire temperature sensors:

• Pt100: JIS C 1604:1997 and IEC 60751:1995.
• Pt100: JIS C 1604:1989 and IEC 60751:1986.
• JPt100: JIS C 1604:1989.

The RTD measurement circuit uses a 1 mA measurement current. This allows the controller to acquire sensor resistance and convert it into temperature data for process monitoring. The supported sensor type and wiring arrangement must match the field instrument configuration.

Electrical Characteristics and Signal Accuracy

The NFAR181 provides an accuracy of ±0.03% of full scale over the 0 to 400 ohm measurement range. The allowable total resistance of the signal source and wiring is 40 ohm or less, with equal wiring resistance required for individual leads.

The input-to-system withstand voltage is 1500 V AC for one minute. This isolation specification defines the electrical withstand capability between the input circuit and the system; it should not be interpreted as a channel-to-channel isolation rating.

Technical Specifications

Parameter	Specification
Model	NFAR181-S00/R8S0
Brand	Yokogawa
Product Type	RTD Input Module
Series	STARDOM FCN/FCJ I/O
Number of Input Channels	12, Isolated
Input Signal	RTD
Supported Sensors	Pt100, JPt100, Three-wire
Measurement Range	0 to 400 ohm
Measurement Current	1 mA
Accuracy	±0.03% of full scale
Allowable Input Voltage	±5 V
Input Resistance (Power ON)	2 MΩ or more
Input Resistance (Power OFF)	2 MΩ or more
Allowable Total Resistance	40 ohm or less, per-wire wiring resistance
Withstanding Voltage	1500 V AC, 1 minute, input to system
Temperature Drift	Max. ±30 ppm/deg C
Data Refresh Cycle	1 second
Maximum Current Consumption	450 mA at 5 V DC
External Connection	Pressure Clamp Terminal
Weight	0.2 kg

Technical specifications: Yokogawa GS 34P02Q31-01E, Analog I/O Modules General Specifications.

Terminal Block and Ordering Configuration

The /R8S00 option is identified in Yokogawa's FCN/FCJ ordering information as a pressure-clamp terminal block for RTD connections, model NFTR8S-00. It provides the field wiring interface for connecting RTD sensor circuits to the input module.

Frequently Asked Questions

Q: How many RTD sensors can the NFAR181 support?

A: The module supports 12 isolated RTD input channels. Each channel is intended for the specified three-wire Pt100 or JPt100 sensor configuration.

Q: Can the NFAR181 accept both Pt100 and JPt100 sensors?

A: Yes. The published specifications identify both Pt100 and JPt100 three-wire inputs. The selected sensor standard must correspond to the actual field sensor.

Q: What is the function of the R8S00 terminal option?

A: It specifies the pressure-clamp terminal block for RTD field connections, identified as Yokogawa NFTR8S-00. This is a terminal configuration option rather than an additional measurement channel or signal type.

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