1794-IR8

About 1794-IR8

The Allen-Bradley 1794-IR8 module 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 fast-update channel rates. It is compatible with 2 and 3-wire RTDs and it can be installed to the 1794-TB3, the 1794-TB2, the 1794-TB3T, the 1794-TB3S, and the 1794-TB3TS terminal base unit. 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 ratings: 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 microAmps. It comes with an accuracy of 0.05% full scale, which is the maximum in the normal mode, and 0.01% full scale, which is typical in the 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. The normal mode rejection ratio of the terminal is -60 dB at 60 Hertz for A/D filter cutoff at 10 Hertz. The 1794-IR8 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 Volts 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 1794-IR8 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 of less than 40 degrees Celsius, and 24 Volts DC maximum for ambient temperatures that are equal to 55 degrees Celsius.

Technical specifications: