The 1791-8AR is an 8 points AC Block I/O module manufactured by Allen Bradley/Rockwell Automation as part of the 1791 Block I/O module series. The module has 8 inputs and 8 relay outputs. These relay an output offer grounded connection and source of voltage to the load and thus requires no extra devices to connect with the load. It has a nominal input current 11 milliamps and voltage of 120 volts AC. The 1791-8AR Block, I/O module, comes in a flexible and compact design. Some of the important parameters of this module that are load-dependent include output voltage rating, power rating output current rating, which makes it deliver either on DC or AC power. It also has four different groups of power ratings, including DC resistive, AC resistive, DC inductive, and AC inductive. The maximum power rating produced by this module is 132 watts AC for 132 volts AC resistive AC output. When installing the 1791-8AR module, ensure you go through the manual provided. Note that insufficient or excessive power can lead to severe damage to devices. This module has no surge limiting circuitry, so it’s essential to ensure that the amount of surge does not exceed the current and voltage rating. It doesn’t come with internal protection to protect it from over-current of up to 150 milliamps and over-voltage of up to 132 volts. To increase load current, do not parallel the output as the output, which turns on first be carrying full load current, and this can be harmful to the devices.

The Allen Bradley 1791-8AR AC Block I/O module, in regard to its inputs, has an on-state voltage range of 79 to 132 volts AC at a frequency range of 47 to 63 hertz. The maximum off-state voltage of this product's inputs is 35 volts. The on-state current is rated at 5 milliamperes minimum at 79 volts at 60 hertz and 12.3 milliamperes maximum at 132 volts at 60 hertz. Additionally, the off-state current for the 1791-8AR's inputs is 2.3 milliamperes minimum at a frequency of 60 hertz. The input impedance rating of the Allen Bradley 1791-8AR AC Block I/O module is 15K ohms maximum at a frequency of 60 hertz. The input signal delay of this device is 1.0 millisecond for off to on, while the input signal delay for on to off is a maximum of 26 milliseconds, as it allows for 1/2 cycle drop-out. 

The Allen Bradley 1791-8AR AC Block I/O module requires an external power supply voltage ranging from 85 to 132 volts AC at a frequency range of 47 to 63 hertz to operate properly. Additionally, the external power supply should have a current rating of 150 milliamperes. The maximum power dissipation rating of this device is 16.5 watts, while the maximum thermal dissipation rating is 56.1 BTU/hr. This Allen Bradley module has physical dimensions that measure 176.5 millimeters x 68.8 millimeters x 98 millimeters, or 6.95 inches x 2.7 inches x 3.85 inches (height x width x depth). The operational temperature appropriate for this module ranges from 0 to 60 degrees Celsius.