1794-IR8

About 1794-IR8

The Allen-Bradley 1794-IR8 is a FLEX RTD I/O module. This 24 Volts DC resistance temperature detector module has 8 differential input channels available and it comes with red and green indicators. This module is ideal for applications that do not require channel fast-update rates. It is compatible with 2 and 3-wire RTDs and can be installed to the 1794-TB3, the 1794-TB2, the 1794-TB3T, the 1794-TB3S, and the 1794-TB3TS terminal base units. This module has a 16-bit resolution across 435 Ohms. Its open TC/RTD circuit detection has an out-of-range reading and it supports RTDs with the following resistance: 100 Ohms Pt α = 0.00385 Euro (-200 to 870 degrees Celsius), 100 Ohms Pt α = 0.003916 U.S. (-200 to +630 degrees Celsius), 200 Ohms Pt α = 0.00385 Euro (-200 to +400 degrees Celsius), 500 Ohms Pt α = 0.00385 Euro (-200 to +630 degrees Celsius), 100 Ohms Nickel α = 0.00618 (-60 to +250 degrees Celsius), 120 Ohms Nickel α = 0.00672 (-60 to +250 degrees Celsius), 200 Ohms Nickel α = 0.00618 (-60 to +250 degrees Celsius), 500 Ohms Nickel α = 0.00618 (-60 to +250 degrees Celsius), and 10 Ohms Copper α = 0.00427 (-200 to +260 degrees Celsius).

The 1794-IR8 module’s RTD excitation current is 718.36 µA. It comes with an accuracy of 0.05% full scale, which is the maximum at normal mode, and 0.01% full scale, which is typical at enhanced mode, at low humidity without calibration. It has 0 Volts common mode input range and a common mode rejection of -120 dB at 60 Hertz and -100 dB at 50 Hertz with A/D filter cutoff at 10 Hertz. Normal mode rejection ratio of the terminal is -60 dB at 60 Hertz for A/D filter cutoff at 10 Hertz. The module also has a channel bandwidth of 0 to 2.62 Hertz or -3 dB, a maximum power dissipation of 3 Watts at 31.2 Volts DC, and a thermal dissipation of 10.2 BTU/hour, also at 31.2 Volt DC. The 1794-IR8’s cold junction compensation range is from -20 to 100 degrees Celsius. The 1794-IR8 has a signal input range of 1 to 433  Ohms and an overvoltage capacity of 35 Volts DC and 25 Volts AC, which is continuous at 25 degrees Celsius. Its isolation voltage has been tested for 60 seconds at 707 Volts DC from the inputs and user power to the logic side. The module has a current certification of 140 mA, a current specification of 150 mA at 24 Volts DC, and voltage specifications of 24 Volts DC nominal, 19.2 to 31.2 Volts DC that includes the 5% AC ripple and for ambient temperatures less than 40 degrees Celsius, and 24 Volts DC maximum for ambient temperatures that are equal to 55 degrees Celsius.

Technical specifications: