Allen-Bradley 1794-IM8 Flex I/O AC Input Module

1794-IM8 Flex I/O 220V AC Digital Input Module

Product Introduction

The Allen-Bradley 1794-IM8 module adds 8 digital AC inputs to your Flex I/O system. Specifically, it accepts a nominal 220V AC supply and handles voltages from 159 to 264V AC. Moreover, each input includes a yellow status indicator for quick diagnostics. In addition, the module offers eight selectable filter times to reduce false triggering from electrical noise. For proper operation, it mounts on the 1794-TBN terminal base unit. Furthermore, this module carries Class I Division 2 certification for hazardous locations. Therefore, the 1794-IM8 is a reliable choice for demanding automation environments.

Key Electrical Specifications

First, this module provides clear input characteristics for AC signals. The nominal on-state voltage is 220V AC, with a minimum of 159V AC and a maximum of 264V AC. Meanwhile, the normal on-state current is 9.88 mA at 220V AC and 60 Hz. Its minimum on-state current is 5.27 mA, while the maximum reaches 13.21 mA. Additionally, the off-state voltage must stay below 40V AC, and the off-state current cannot exceed 2.6 mA. Furthermore, the nominal input impedance is 22.3 kΩ, with a typical input current of 10 mA at 220V AC. This module draws a FlexBus current of 30 mA at 5V DC. Finally, its maximum power dissipation is 4.7 W at 264V AC, with thermal dissipation at 16.2 BTU/hr.

Selectable Input Filter Times

The 1794-IM8 stands out with its user-configurable input filter settings. For instance, you can select from eight different filter times through the output image table. By default, the module uses Filter Time 0, which provides an Off-to-On delay of 7.5 ms and an On-to-Off delay of 26.5 ms. For applications with more electrical noise, however, you can choose longer filter times. For example, Filter Time 7 extends the Off-to-On delay to 42 ms and the On-to-Off delay to 60.5 ms. As a result, this flexibility allows you to balance response speed with noise immunity. Consequently, the 1794-IM8 adapts well to various field conditions.

Isolation and Protection

The 1794-IM8 provides robust isolation between the user system and the field side. In fact, it is 100% tested at 2600V DC for 1 second for user-to-system isolation. Nevertheless, there is no isolation between individual channels, which is typical for this type of AC input module. Similarly, there is no isolation between customer power and the input channels. Additionally, the module's keyswitch position is set to 8. For safety, users should install external fuses to protect against overcurrent conditions. This ensures the module operates safely and reliably over its service life.

Mechanical and Environmental Parameters

The Allen-Bradley 1794-IM8 measures just 46 mm (H) x 94 mm (W) x 53 mm (D) , which is 1.8 x 3.7 x 2.1 inches. Moreover, its lightweight design weighs only about 141 grams. The module operates in temperatures from 0 to 55 °C and can be stored between -40 and 85 °C. In addition, it handles operating shocks of 30g and non-operating shocks of 50g. Vibration testing at 5g from 10 to 500 Hz confirms its durability. Meanwhile, the non-condensing relative humidity tolerance is 5 to 95%. Finally, this module uses an open-style enclosure and is rated for Class I Division 2 hazardous locations.

Installation and Compatibility

Mounting the 1794-IM8 is simple using either DIN rail or screw mounting. First, it requires the 1794-TBN terminal base unit for proper installation. Next, the module provides 8 yellow status indicators on the field side. These LEDs are driven by the customer device and show each input's state. Furthermore, wire size supports up to 12 gauge (4 mm²) stranded conductors. The module fits into the Flex I/O system with a keyswitch position of 8. Finally, always ensure the FlexBus is fully seated before operation. This guarantees proper communication with the adapter.

Packaging List

• Allen-Bradley 1794-IM8 Digital Input Module (1 unit)

• Installation Instructions Manual (Publication 1794-5.57)

Shipping Information

We ship all orders using reputable global carriers. Specifically, your 1794-IM8 will be dispatched via FedEx, UPS, or DHL. This ensures fast and reliable delivery to your facility.

Frequently Asked Questions (FAQ)

Q1: What terminal base unit is required for the 1794-IM8?
The 1794-IM8 requires the 1794-TBN terminal base unit. This base provides the necessary connections for the AC inputs and the FlexBus interface.

Q2: How do I change the input filter time on the 1794-IM8?
You select the filter time through the output image table in your control system. Specifically, eight settings are available, ranging from 7.5 ms to 42 ms for Off-to-On delays. The default is Filter Time 0.

Q3: Is the 1794-IM8 suitable for 240V AC systems?
Yes, the 1794-IM8 operates with a nominal 220V AC but accepts voltages from 159 to 264V AC. Therefore, it is fully suitable for 240V AC systems as well.

Q4: Does the 1794-IM8 provide isolation between input channels?
No, there is no isolation between individual channels on the 1794-IM8. However, the module provides tested isolation between the user system and the field side at 2600V DC.

Q5: What certifications does the 1794-IM8 hold?
The Allen-Bradley 1794-IM8 carries UL, CSA, and CE markings. Additionally, it is certified for Class I Division 2, Groups A, B, C, D, and Class I Zone 2 Group IIC hazardous locations.