Allen-Bradley 1746-IA8 AC Input Module SLC 500

1746-IA8 8-Channel 120V AC Digital Input Module

Product Introduction

The 1746-IA8 comes from the reliable SLC 500 I/O series by Allen‑Bradley. This digital AC input module provides eight independent input channels. Its voltage range runs from 85V to 132V AC, making it ideal for 100–120V AC applications.

Additionally, this module has North American Hazardous Location Approval. Therefore, you can safely operate it in certain hazardous environments. It occupies just one slot in the SLC 500 chassis.

The 1746-IA8 draws 50mA from the 5V DC backplane. It takes no current from the 24V DC backplane. Consequently, it places a modest load on your system power supply.

For accurate signal detection, the off‑state maximum current sits at 2mA. The off‑state maximum voltage reaches 30V AC. Meanwhile, the nominal input current equals 12mA at 120V AC.

Signal delays remain predictable. Maximum ON delay is 35ms, and maximum OFF delay is 45ms. These timing characteristics work well for push buttons, limit switches, and proximity sensors.

Technical Specifications

Here are the complete technical details for the 1746-IA8:

• Inputs: 8 (non‑isolated, one common)

• Operating voltage: 85–132V AC (nominal 100–120V AC)

• Backplane current (5V DC): 50mA

• Backplane current (24V DC): 0mA

• Off‑state max current: 2mA

• Off‑state max voltage: 30V AC

• Nominal input current: 12mA at 120V AC

• Signal ON delay: 35ms max

• Signal OFF delay: 45ms max

• Inrush current: 0.8A max

• Inrush current duration: 0.5ms max

• Operational frequency: 47–63Hz

• Step response: 100ms in, 2.5ms out

• Power dissipation per point: 0.27W

• Thermal dissipation: 0.25W (min) to 2.4W (max)

• Isolation voltage: 500V DC (communication), 1500V AC (backplane)

This I/O module uses 1746-HT or 1746-HCA connectors for field wiring. It mounts directly into any SLC 500 chassis slot.

Hazardous Location & Environmental Ratings

The 1746-IA8 holds North American Hazardous Location Approval. This rating permits installation in specific hazardous environments. Always check local codes before installation.

The module measures 5 inches high by 2 inches wide by 6 inches deep (13 cm x 5 cm x 15 cm). It weighs 0.23 kg, and the gross packaged weight is 0.35 kg.

Operating temperature ranges from 32°F to 140°F (0°C to 60°C). The enclosure style is open, so you must install it inside a suitable control cabinet.

Furthermore, the front panel includes status indicators. These LEDs show the live status of each AC input channel. Troubleshooting becomes much faster with visual feedback.

Installation Guidelines

Follow these steps to install the 1746-IA8 correctly:

First, power down the entire SLC 500 chassis. Then, align the 1746-IA8 with the card guides inside the selected slot. Push it firmly until the backplane connector fully engages.

Next, tighten the two retention screws to lock the module in place. For wiring, use the 1746-HT or 1746-HCA I/O connector. Connect AC live wires to the input terminals and neutral wires to the common terminal.

Finally, confirm the AC supply stays between 85V and 132V AC. Never apply DC voltage to any input channel. Restore chassis power and verify the status LEDs respond correctly.

Packaging List

• 1 x Allen‑Bradley 1746-IA8 digital AC input module

• 1 x I/O wiring connector (1746-HT or 1746-HCA)

• 1 x installation instruction sheet

Note: Certificates and warranty documents are not included. The module ships in anti‑static protective packaging.

Shipping method: FedEx, UPS, or DHL (express delivery with full tracking).

Frequently Asked Questions (FAQ)

1. Can the 1746-IA8 be used in hazardous locations?
Yes, the 1746-IA8 holds North American Hazardous Location Approval. However, you must follow all local installation regulations.

2. What is the difference between 1746-IA4 and 1746-IA8?
The 1746-IA4 has 4 inputs and draws 35mA. The 1746-IA8 has 8 inputs and draws 50mA. Both share the same voltage range and delay characteristics.

3. Does this module support 240V AC operation?
No, the 1746-IA8 only accepts 85–132V AC. For 240V AC applications, consider the 1746-IA16 or other high‑voltage SLC 500 modules.

4. Why do my inputs stay on when the field device is off?
Check the off‑state leakage current. If it exceeds 2mA, the input may not turn off. Add a bleeder resistor in parallel with the input.

5. What is the maximum thermal dissipation I need to handle?
The 1746-IA8 dissipates up to 2.4 watts maximum. Ensure your control cabinet has adequate ventilation for this heat load.