Description
1. At-A-Glance Executive Brief
- Model: 1756-OW16I
- Brand: Allen-Bradley (Rockwell Automation)
- Part Type: ControlLogix 16-Point Isolated Relay Output Module
- Lifecycle Status: Active / Mature Legacy Support
- System Compatibility: ControlLogix 1756 Chassis and Standard Removable Terminal Blocks (RTB)
- Weight: 0.52 kg (Shipping weight approx. 2 kg)
2. Technical Introduction
Plant maintenance teams replacing failed legacy I/O often run into sudden ground loops or voltage mismatch issues when driving mixed AC and DC field loads from a single PLC rack. Unprotected relay contacts subjected to heavy inductive loads suffer from premature pitting, welding, and catastrophic channel failure, leading to unplanned downtime on continuous process lines. The Allen-Bradley 1756-OW16I resolves this by providing 16 individually isolated normally open relay outputs, handling both 5 to 125V DC and 10 to 240V AC ranges within a single slot of a ControlLogix chassis to maintain strict electrical separation between field devices and backplane logic.
3 Core Technical Specifications
| Parameter | Value |
| Outputs | 16 N.O. Individually Isolated |
| Operating Voltage Range | 5…125V DC, 10…240V AC |
| Pilot Duty Rating | C300 / R150 |
| Max Output Current | 1A @ 5-30V DC, 0.5A @ 48V DC, 1.5A @ 120V AC |
| Min Load Current | 10 mA per point |
| Off-State Leakage Current | 1.5 mA per point max |
| Isolation Voltage | 250V continuous (routine tested @ 1350V AC) |
| Slot Width | 1 |
| Backplane Power Draw | 4.4 W total |
| Expected Contact Life | 300K cycles resistive, 100K cycles inductive |
4. Field Engineer’s Tech Notes
- Inductive Load Arc Suppression: This module lacks internal snubber circuits or built-in fusing. Always install external flyback diodes across DC inductive loads (such as solenoids or small DC relays) and RC snubbers or MOVs across AC loads to prevent severe contact pitting and extend relay life.
- Minimum Load Threshold: Operating these relay contacts below the 10 mA threshold causes oxidation buildup on the contact surfaces over time, resulting in high contact resistance and intermittent signal loss. Verify your connected load draws sufficient current or add a bleeder resistor if switching low-power PLC inputs or electronic loads.
5. Adaptive QA & Testing Protocol
Every pre-owned or New Surplus (NSFP) 1756-OW16I module undergoes rigorous bench testing before dispatch. Technicians execute individual channel actuation verification by energizing the backplane interface and monitoring mechanical relay closure using high-precision digital multimeters. Continuity testing confirms zero-ohm contact closure under load, while dielectric withstand testing checks channel-to-channel and channel-to-backplane isolation integrity. Detailed test reports and verification videos are available upon request to support your procurement audit trail.
6. Buyer’s FAQ
- Q: What warranty is included with this 1756-OW16I module?
A: All New Surplus and fully refurbished units come with a comprehensive 24-month replacement warranty covering component performance and hardware integrity.
- Q: Are these units shipped with the Removable Terminal Block (RTB)?
A: Standard supply includes the core module. Standard 36-pin RTBs (such as the 1756-TBNH or 1756-TBSH) can be bundled upon request depending on your cabinet wiring needs.
- Q: How does this module integrate during legacy system migration?
A: The 1756-OW16I fits directly into any standard ControlLogix 1756 chassis slot, requiring zero physical rack modifications or complex I/O mapping changes when replacing older Series A or B revisions.
- Q: What are the typical lead times for urgent plant shutdowns?
A: Expedited same-day dispatch is available for stock items to minimize downtime during emergency maintenance events.
