Allen-Bradley 1746-IM8 AC Input Module

1746-IM8 SLC 500 Digital AC Input Module

Product Introduction

The 1746-IM8 is a digital AC input module from the Allen‑Bradley SLC 500 series. Rockwell Automation manufactures this unit with eight isolated channels. It accepts a voltage range of 170–265V AC at 47–63 Hz. Many industrial facilities choose this module for its robust performance in moderate to high-voltage AC sensing.

Additionally, the 1746-IM8 draws only 50 mA from the 5V DC backplane. It also features zero current draw from the 24V DC backplane. This efficiency makes it suitable for dense I/O configurations. Furthermore, users appreciate its dual signal delay options of 35 ms or 45 ms.

Technical Specifications

The 1746-IM8 operates as an open‑type equipment piece. It is intended for industrial environments with Pollution Degree 2 (per EN/IEC 60664‑1). For instance, its off‑state current sits at just 2 mA, preventing false triggering.

Key electrical parameters include:

• Inputs: 8 (sink/source, AC)

• Voltage range: 170–265V AC

• Frequency: 47–63 Hz

• Signal delay: 35 ms or 45 ms (selectable)

• Off‑state current max: 2 mA

• Backplane current (5V DC): 50 mA

• Backplane current (24V DC): 0 mA

Application notes:
This module works well for general‑purpose 125V DC inputs as well. However, always verify voltage compatibility before wiring. You must use it with compatible I/O connections like 1746-HT or 1746-HCA terminal blocks.

Mechanical and Environmental Ratings

The 1746-IM8 withstands tough conditions without losing accuracy. Specifically, its operating temperature range is -25°C to 60°C (-13°F to 140°F). Non‑operating temperatures stretch from -40°C to 85°C (-40°F to 185°F).

Other environmental specifications:

• Relative humidity: 5% to 95% non‑condensing

• Operating vibration: 1.0 g at 5–2000 Hz

• Operating shock: 30 g

• Total heat dissipation: 3.1 Watts

• Heat per point: 0.35 Watts

Moreover, step response is rated at 100 ms in and 2.5 ms out. This fast response supports real‑time control loops. Therefore, you can deploy the 1746-IM8 in applications requiring quick signal detection.

Installation Guidelines

Proper installation ensures safety and long service life. First, always cut all power to the SLC 500 chassis before inserting or removing the 1746-IM8. Next, secure the module in an enclosure rated for industrial use. Remember that this unit is open‑type equipment. Only authorized personnel should access the enclosure.

For wiring, use the 1746-HT or 1746-HCA I/O connection blocks. Maintain proper clearance between AC inputs and low‑voltage wiring. Additionally, do not apply voltages above 265V AC to any channel. Exceeding this limit can cause permanent damage or fire hazards.

Hazardous environment precautions:
The 1746-IM8 can operate in some hazardous locations. However, you must follow strict safety rules. Keep equipment connected only until power is cut and the area is secured. Never hot‑swap the module in a hazardous zone.

Packaging List

Your shipment includes the following items:

• One Allen‑Bradley 1746-IM8 digital AC input module

• One product data sheet (printed)

• One anti‑static protective bag

Note: This package does not include terminal blocks, cables, certificates, or warranty documents. Terminal blocks such as 1746-HT and 1746-HCA must be ordered separately.

Shipping Information

We ship all orders using trusted global carriers. Your 1746-IM8 module will be dispatched via:

• FedEx

• UPS

• DHL

Tracking numbers will be provided within 24 hours of shipment. Standard delivery takes 3–7 business days depending on your location.

Frequently Asked Questions (FAQ)

1. Can I use the 1746-IM8 with 120V AC signals?
No, the 1746-IM8 requires a minimum of 170V AC. For 120V AC applications, please use the 1746-IA8 or 1746-IA16 modules instead.

2. What happens if I connect DC voltage to this module?
Connecting DC voltage can damage the internal circuitry. The 1746-IM8 is designed exclusively for AC inputs. Always double-check your signal type before wiring.

3. How do I select the signal delay time?
The 1746-IM8 does not have a physical switch. You configure the delay through your SLC 500 processor's I/O configuration software. Choose either 35 ms or 45 ms per channel.

4. Is the 1746-IM8 compatible with a 1746-A10 chassis?
Yes, the 1746-IM8 fits all SLC 500 chassis, including the 1746-A10, 1746-A13, and 1746-A7. Simply insert it into any available slot.

5. Why does my module show no input activity?
First, verify the AC voltage is between 170V and 265V. Next, check the wiring on your 1746-HT or 1746-HCA block. Also, ensure the backplane connection is secure. Finally, confirm your processor's configuration enables the input channels.