1. Description:

The Allen-Bradley 20SD600NEN is an Allen-Bradley PowerFlex 20S SCR Bus Supply. It’s a key component in certain industrial drive systems, specifically designed to convert incoming three-phase AC line voltage (400/480V AC) into a common DC bus voltage (540-650 VDC) at a substantial current rating of 600 Amps. This is a “Stand Alone” configuration, meaning it functions as an independent power source for a common DC bus, supplying power to multiple AC drives that share that bus. It’s a non-regenerative unit, primarily acting as a rectifier.

2. Application Scenarios:

Imagine a large printing press in a commercial print facility, where multiple sections (feeding, printing units, drying, cutting, and folding) are driven by individual AC motors, all requiring precise speed and synchronization. Historically, each AC drive might have had its own rectifier section, leading to redundant components and potential inefficiencies. The implementation of the Allen-Bradley 20SD600NEN PowerFlex SCR Bus Supply provides a centralized and efficient power solution. This unit would be installed to convert the facility’s incoming AC power into a shared DC bus voltage, to which all the individual PowerFlex AC drives (e.g., PowerFlex 70, 700 series) for the printing press sections would connect. This common bus architecture, powered by the 20SD600NEN, simplifies the power distribution, reduces overall cabling, and enhances energy efficiency by allowing the drives to share energy across the bus, even if the 20SD600NEN itself is non-regenerative. This directly addresses the pain points of complex wiring and distributed power conversion, leading to a more streamlined and reliable power supply for large multi-motor systems.

3. Parameter:

Main Parameters Value/Description Product Model: Allen-Bradley 20SD600NEN Manufacturer: Allen-Bradley (Rockwell Automation) Product Category: PowerFlex SCR Bus Supply / Common Bus Power Supply Input Voltage: 400/480V AC, 3 Phase Output DC Bus Voltage: 540-650 VDC (typical for 400/480V AC input) Output Current: 600 Amps Configuration: Stand Alone (provides power for multiple drives on a common DC bus) Operation: Non-regenerative (converts AC to DC, does not return energy to AC line) Rectifier Type: Six-pulse, full-wave, three-phase SCR bridge rectifier unit Frequency Rating: 50-60 Hz Dimensions (H x W x D): Approx. 41.0 cm x 90.0 cm x 61.0 cm (or 16.14 x 35.43 x 24.02 inches) Weight: Approximately 51.4 kg (113 lbs) Protection: RC snubber circuit for dampening over-voltages, over-temperature sensor in heat sink. Enclosure: Typically designed for cabinet mounting (no specific NEMA/IP rating specified for standalone unit, assumes integration into enclosure). Status: Product is often listed as “end of life” by Rockwell Automation but available through surplus and repair channels.

4. Technical Principles and Innovative Values:

The Allen-Bradley 20SD600NEN PowerFlex SCR Bus Supply embodies several key technical principles and innovative values within the context of common bus drive systems:

• Innovation Point 1: Centralized DC Bus Power Supply: The core principle of the 20SD600NEN is to centralize the AC-to-DC conversion for multiple AC drives. Instead of each drive having its own rectifier, this single, high-capacity SCR bridge provides a common DC bus. This design simplifies power distribution, reduces the number of components required (especially rectifier sections in individual drives), and can lead to a more compact and cost-effective overall system for multi-axis or multi-motor applications.
• Innovation Point 2: Robust SCR Bridge Rectification: Utilizing a six-pulse, full-wave, three-phase SCR (Silicon Controlled Rectifier) bridge, the 20SD600NEN provides a robust and controllable means of converting AC to DC. While it’s non-regenerative, the SCR technology allows for controlled ramp-up of the DC bus, providing a soft-start for the entire common bus system, which is beneficial for protecting connected drives and optimizing power quality during startup.
• Innovation Point 3: Enhanced System Integration with Common Bus: The true value of this bus supply lies in its ability to enable a common DC bus architecture. This allows individual drives connected to the bus to dynamically share energy. For example, if one motor is braking (regenerating energy), that energy can be immediately consumed by another motor that is accelerating, thus reducing the total energy drawn from the AC line and potentially reducing overall energy consumption in applications with frequent start/stop cycles or varying loads.

5. Application Cases and Industry Value:

In a modern automated warehouse, large conveyor systems with numerous independent sections transport packages. Each section is driven by an AC motor controlled by a VFD. To manage power efficiently and simplify the electrical infrastructure, the warehouse implemented a common DC bus architecture powered by an Allen-Bradley 20SD600NEN PowerFlex SCR Bus Supply. This 600A bus supply provided the central DC voltage for all the AC drives controlling the various conveyor sections. As packages moved through the system, some conveyor sections might decelerate (generating energy) while others accelerate (consuming energy). The common bus allowed this energy to be shared instantaneously among the drives. This setup, enabled by the 20SD600NEN, significantly reduced the overall energy consumption of the conveyor system by up to 15% compared to individual drive rectifiers. It also simplified the electrical panel design, reduced wiring complexity, and improved the reliability of the power delivery to the drives, resulting in considerable operational savings and reduced maintenance.

6. Related Product Combination Solutions:

The Allen-Bradley 20SD600NEN PowerFlex SCR Bus Supply is typically integrated into a larger common bus drive system:

• Allen-Bradley PowerFlex AC Drives (e.g., PowerFlex 70, PowerFlex 700, PowerFlex 755): These are the individual variable frequency drives that connect directly to the DC output of the 20SD600NEN. They control the AC motors of the application.
• Common Bus Diodes/Fuses: Used to protect individual drives on the common bus and manage energy flow.
• Braking Resistors / Braking Modules: While the 20SD600NEN is non-regenerative, if the overall system’s regenerated energy exceeds the capacity for absorption by other drives on the bus, external braking resistors might be required to dissipate excess energy.
• System Contactor / Circuit Breaker: For isolating the 20SD600NEN from the incoming AC line.
• Line Reactors / Isolation Transformers: Often installed on the AC input side of the 20SD600NEN to reduce harmonic distortion and protect the bus supply from line disturbances.
• Allen-Bradley PLCs (e.g., ControlLogix, CompactLogix): Provide supervisory control and coordination for the overall system, including starting/stopping the bus supply and commanding the individual drives.
• HMI Panels (e.g., PanelView Plus): For operator interface, monitoring system status, and troubleshooting.

7. Installation, Maintenance, and Full-Cycle Support:

The Allen-Bradley 20SD600NEN PowerFlex SCR Bus Supply is designed for integration into industrial electrical cabinets. Installation involves securely mounting the unit, connecting the three-phase AC input power, and connecting the DC bus output to the common bus terminals of the individual PowerFlex AC drives. Due to its high current rating, proper sizing and routing of power cabling, along with meticulous grounding, are critical for safety and optimal performance. Commissioning typically involves verifying all electrical connections and ensuring the bus supply is properly integrated into the overall drive system’s control scheme.

Routine maintenance for the 20SD600NEN focuses on ensuring adequate cooling airflow through the unit’s heatsinks, keeping the electrical connections clean and tight, and visually inspecting for any signs of overheating or damage. The internal over-temperature sensor and snubber circuits contribute to its reliability. As the 20SD600NEN is listed as “end of life” by Rockwell Automation, accessing full manufacturer support for new purchases may be limited. However, a robust ecosystem of industrial automation spare parts suppliers offers new, surplus, or refurbished units, as well as repair services. These suppliers typically provide their own warranties and technical assistance. Migration paths to newer Rockwell Automation common bus solutions (e.g., specific PowerFlex 7000 configurations or other common bus architectures) would also be an option if system upgrades are planned.