Allen-Bradley 1746-IA4 AC Input Module SLC 500

1746-IA4 4-Channel 120V AC Digital Input Module

Product Introduction

The 1746-IA4 belongs to the trusted SLC 500 family from Allen‑Bradley. This digital AC input module handles four independent AC inputs. Its voltage range spans from 85V to 132V AC, making it suitable for 100–120V AC applications.

Additionally, the module consumes just 35mA from the 5V DC backplane. It draws no current from the 24V DC backplane. Therefore, it places a very low load on your power supply.

For reliable signal reading, the 1746-IA4 has a maximum off‑state current of 2mA. The off‑state voltage goes up to 30V AC. Meanwhile, the nominal input current sits at 12mA when supplied with 129V AC.

The signal delay is consistent. Maximum ON delay equals 35ms, and maximum OFF delay equals 45ms. This response works well for most industrial sensors and push buttons.

Furthermore, the module supports a frequency range of 47–63Hz. It handles inrush current for up to 500 microseconds. The step response reaches 100ms for input and 2.5ms for output.

Technical Specifications

Here are the key technical details for the 1746-IA4:

• Inputs: 4 (non‑isolated, one common)

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

• Backplane current (5V DC): 35mA

• Backplane current (24V DC): 0mA

• Off‑state max current: 2mA

• Off‑state max voltage: 30V AC

• Nominal input current: 12mA at 129V AC

• Signal ON delay: 35ms max

• Signal OFF delay: 45ms max

• Inrush current duration: 500µs max

• Operational frequency: 47–63Hz

• Step response: 100ms in, 2.5ms out

• Power dissipation per point: 0.27W

• Thermal dissipation: 0.175W (min) to 1.3W (max)

This I/O module uses 1746-HT and 1746-HCA for field wiring connections. It occupies exactly one slot in the SLC 500 chassis.

Mechanical & Environmental Parameters

The 1746-IA4 measures 5 inches high by 2 inches wide by 6 inches deep (13 cm x 5 cm x 3.8 cm). Its weight is only 0.17 kg, and the gross weight with packaging is 0.28 kg.

Operating temperature ranges from 32°F to 140°F (0°C to 60°C). The enclosure is open‑style, designed for installation inside a control cabinet.

Moreover, the front panel includes a status display. This LED indicator shows the presence of AC power on each input channel. Troubleshooting becomes faster because you can see channel status immediately.

Installation Guidelines

Follow these steps when installing the 1746-IA4:

First, ensure the SLC 500 chassis is powered off. Then, align the module with the card guides inside the slot. Slide it firmly until the backplane connector seats completely.

Next, tighten the retention screws to secure the module. For wiring, use 1746-HT or 1746-HCA I/O connectors. Connect AC live and neutral wires according to the labeling on the module.

Finally, verify the AC voltage source stays within 85–132V AC. Do not apply DC voltage to any input. Turn on the chassis power and check the status indicators.

Packaging List

• 1 x Allen‑Bradley 1746-IA4 digital AC input module

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

• 1 x quick reference guide

Note: No certificates or warranty documents are included. The module ships in anti‑static packaging.

Shipping method: FedEx, UPS, or DHL (express delivery, fully tracked).

Frequently Asked Questions (FAQ)

1. Can the 1746-IA4 accept DC voltage?
No, the 1746-IA4 is designed only for AC voltages between 85V and 132V AC. DC inputs will damage the module.

2. What is the maximum number of inputs on this module?
It provides exactly four AC inputs. For more channels, use other SLC 500 modules like the 1746-IA8 or 1746-IA16.

3. Does the module require an external power supply?
No, it draws all necessary power from the 5V DC backplane of the SLC 500 chassis. No external 24V DC supply is needed.

4. Why does my 1746-IA4 show an incorrect signal?
Check the off‑state current. If field device leakage exceeds 2mA, the input may stay ON incorrectly. Add a loading resistor if needed.

5. What happens if I exceed the inrush current duration?
The module may overheat or fail. Keep inrush current pulses shorter than 500 microseconds to ensure reliable operation.