I/O Module Allen-Bradley 1791-24AR

Allen-Bradley 1791-24AR: 24-Input, 8-Relay Output Block I/O Module

Technical Specifications

• Brand: Allen-Bradley
• Model: 1791-24AR
• Product Line: 1791 Block I/O
• Input Channels: 24 AC Inputs (3 groups of 8)
• Output Channels: 8 Relay Outputs (Normally Open contacts)
• Input Voltage Range: 79-132V AC
• Nominal Input Voltage: 120V AC, ~11 mA
• Input Off-State Leakage: 2.3 mA min @ 35V AC max
• External Power Supply: 85-132V AC
• Module Dimensions: 3.85"D x 4.35"W x 6.95"H
• Weight: 2.50 lbs (1.13 kg)

Relay Output Specifications

• The eight outputs are electromechanical relays with NO (Normally Open) contacts.
• Relay contacts can switch either AC or DC voltage, providing maximum application flexibility.
• Maximum Resistive Current: 1.0 A @ 20-132V AC or 20-30V DC.
• Output Rating depends on Load Type:
  • Resistive Load: Up to 1.0 A (AC or DC, as above). At 0.2 A, voltage can be up to 125V DC.
  • Inductive AC Load (cos Φ = 0.4): 0.5 A @ 20-132V AC.
  • Inductive DC Load (L/R = 7 ms): 1.0 A @ 20-30V DC.
  • DC Steady State: 0.1 A @ 125V DC.
• Always refer to the load-specific ratings to ensure reliable and safe operation.

Installation & Integration

• The 1791-24AR is designed for Remote I/O architecture, acting as an adapter on the network.
• It requires connection to an RIO scanner in a compatible Allen-Bradley PLC chassis.
• Installation follows standard 1791 series practices for mounting and wiring.
• Use appropriate gauge wiring for both the 120V AC inputs and the relay output load circuits.
• Consider inrush currents and load types (inductive, resistive, lamp) when sizing outputs.
• For inductive loads, external suppression (like flyback diodes for DC) is recommended to protect relay contacts.

Frequently Asked Questions

• What makes the 1791-24AR different from the 1791-24A8?
  The key difference is the output type. The 1791-24AR has 8 relay outputs that can switch AC or DC, while the 1791-24A8 has 8 solid-state AC outputs only.
• What voltages can the relay outputs on the 1791-24AR switch?
  The relay contacts are versatile. They can switch AC voltage (20-132V AC) or DC voltage (20-125V DC), depending on the current rating.
• What is the maximum current for the relay outputs?
  The maximum current is 1.0 Amp for resistive loads at lower voltages. The rating decreases for inductive loads or higher voltages—please check the detailed specs above.
• Are the relay outputs on this module fused internally?
  No, the relay output circuits are not internally fused. External fusing or circuit protection is required for each output load.
• Do you have this module in stock, and how do you ship?
  Yes, we stock the 1791-24AR and ship within 3-5 days via major carriers like DHL, FedEx, or UPS.
• Can I return the module if it doesn't suit my application?
  Absolutely. We offer a 30-day return period for products in original condition.

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