Purchase now: Allen-Bradley 1756-CPR2 Redundant Power Cable
Purchase now: Atlantechdrives provides you the 1756-CPR2, an absolutely essential, highly specialized power transmission cable engineered specifically by Rockwell Automation for the ControlLogix 1756 programmable automation system. In critical infrastructure applications—such as continuous oil refining, pharmaceutical batching, or high-speed automotive stamping—a simple power supply failure cannot be allowed to crash the central processor. To achieve true power redundancy, engineers utilize two identical redundant power supplies (such as the 1756-PA75R) mounted in a separate, dedicated power chassis (the 1756-PSCA2). The 1756-CPR2 is the critical physical umbilical cord that connects this redundant power chassis directly to the main ControlLogix PAC chassis. Measuring exactly 0.91 meters (3.0 feet) in length, this heavy-duty, multi-conductor cable safely and efficiently transmits the highly regulated 1.2V, 3.3V, 5.1V, and 24V DC backplane currents generated by the redundant supplies directly into the processor rack. Without this specific, factory-molded cable, building a certified Allen-Bradley redundant power architecture is physically impossible.
Technical Specifications of the 1756-CPR2
The 1756-CPR2 is not a standard electrical wire; it is a highly engineered, shielded, low-impedance cable assembly designed to prevent voltage drop and electromagnetic interference (EMI) from corrupting the delicate DC currents feeding the main processor’s RAM and logic circuits.
- Part Number: 1756-CPR2
- Platform Compatibility: ControlLogix 1756 Redundant Power Systems
- Cable Length: 0.91 meters (3.0 feet)
- Primary Function: Connects the 1756-PSCA2 redundant power chassis to the main 1756-Axx chassis adapter
- Compatible Power Supplies: 1756-PA75R, 1756-PB75R, 1756-PC75R
- Connector Type: Factory-molded, highly secure multi-pin locking connectors
Expert Tips: The 3-Foot Limitation and Cabinet Layout
When designing an industrial control panel that requires power supply redundancy, cabinet layout planning is absolutely critical. Expert Tip: The 1756-CPR2 cable is strictly limited to 0.91 meters (3 feet). You cannot extend this cable, splice it, or order a custom 10-foot version from Rockwell. The 3-foot limitation is a strict electrical engineering constraint designed to prevent fatal voltage drops across the 5.1V and 1.2V DC traces under heavy amperage loads. Because of this short umbilical cord, the dedicated redundant power supply chassis (the 1756-PSCA2) must be physically mounted immediately adjacent to, or directly below, the main ControlLogix processor chassis inside the electrical enclosure. Failing to account for this short cable length during the AutoCAD panel design phase will result in physical impossibility during the actual panel build on the shop floor.
Installation Advice: Strain Relief and Connector Seating
The multi-pin connectors on the ends of the 1756-CPR2 carry high amperage DC currents. During installation, technicians must ensure that the connectors are pushed completely flush into the receptacles on both the PSCA2 chassis and the main chassis adapter, and that the locking clips are fully engaged. A loose connection will cause severe electrical arcing, micro-voltage drops, and sudden, inexplicable backplane faults that will randomly crash the main CPU. Furthermore, despite its heavy-duty jacket, you must respect the minimum bend radius of the cable. Do not kink the 1756-CPR2 at a hard 90-degree angle to make it fit inside tight plastic wire ducting, as this will fracture the internal copper strands over time due to natural machine vibration.
Frequently Asked Questions (FAQs)
Q: Can I use two 1756-CPR2 cables to connect a second expansion chassis to the redundant power supplies?
A: No. A redundant power supply pair (housed in the PSCA2 chassis) is designed to power only one single ControlLogix chassis. If you have a multi-chassis system, each individual chassis requires its own dedicated set of redundant power supplies, its own PSCA2 chassis, and its own 1756-CPR2 cable.
Q: What happens if one of the power supplies fails while the CPR2 cable is connected?
A: That is the exact purpose of the system. The solid-state circuitry inside the PSCA2 adapter seamlessly transfers the entire electrical load to the surviving power supply in milliseconds. The 1756-CPR2 cable continues to transmit the steady DC voltage to the main chassis, and the processor never experiences a drop in power.
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This ControlNet redundancy cable is technically essential for interconnecting modules such as the 1756-CNB bridge.
