Interconnection
How to ensure safe and efficient modular BESS deployments using pluggable battery pole connectors
By Rolf Horn, applications engineer at Digi-Key Electronics T
he use of modular battery energy storage systems (BESSs) is growing in residential, industrial, and utility- scale installations. Comprising multiple interconnected battery
modules, BESSs provide backup power if the main grid fails, regulate peak energy usage in industrial settings, and support the grid integration of renewable energy sources such as wind and solar. While their modular architecture simplifies installation, enables scalability, and supports the efficient replacement of worn- out battery modules, designers need to be particularly careful about their choice of battery pole connectors.
Along with meeting the latest safety and performance standards, as well as being rugged and cost-effective, designers need to factor in connector flexibility for orientation and the ability to withstand multiple insertion/ withdrawal cycles, while maintaining minimal electrical contact resistance to prevent overheating. Also, to ensure user safety, features like polarity reversal protection and being fully touch-proof should be on the checklist of requirements.
This article discusses the issues associated with BESS module connectivity. It then introduces and shows how to apply a line of pluggable battery pole connectors from Phoenix Contact that are designed for BESS applications.
Performance requirements for battery pole connectors The performance expectations for battery pole connectors vary between residential, commercial, and utility applications (Figure 1). While safety is a priority for all, residential installations benefit from high levels of flexibility. Maintenance considerations are important in commercial BESS designs. Utility- scale BESS installations place less emphasis on flexibility but are the most demanding application overall, with the expectation of fast installation (low labour time), high safety, low failure rates, low cost, and efficient maintenance. Selection of the right
50 April 2022
of 2, making them suitable for use in environments where only non-conductive pollution occurs, except that occasionally a temporary conductivity condition caused by condensation may occur.
Figure 1: Different applications have varying requirements for BESS connector performance. The right battery pole connector can meet the demands of all three application categories. (Image source: Phoenix Contact).
connectivity solution is critical to meet the varying performance demands. Cable lug wiring assemblies are a common method for connecting the battery modules in a BESS. Lug connectors are relatively inexpensive, but they have several disadvantages when used in a BESS installation: • They suffer from poor standardization and lack application flexibility
• Manually connecting and tightening the nuts on each lug connector is a time-consuming process and can be prone to wiring errors
• If the nuts are not properly tightened, the connection can have a high resistance, resulting in overheating
• Lug connectors are not protected from the environment; when used in outdoor enclosures the reliability of lug connectors can be reduced by exposure to dust or low- pressure water jets as well as condensation and water spray
• Lug connectors are not touch-safe and do not comply with current safety standards, presenting a potential shock hazard to installers and maintenance personnel To overcome the drawbacks of using lug connectors, designers can turn to specially designed pluggable battery pole connectors from Phoenix Contact that meet the requirements of consumer, commercial/ industrial and utility BESS installations (Figure 2).
These connectors offer good accessibility and the flexibility to connect to the battery
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pole from any direction for quick installation, with low contact resistance. They include polarity-reversal protection and are fully touch-proof for operator safety. An IP65 rated housing provides protection from dust ingress and against low-pressure water jets from any direction, plus protection from condensation and water spray.
The connectors have an International Electrotechnical Commission (IEC) overvoltage category III rating and are capable of withstanding transient voltages in fixed installations such as outdoor cabinets that house BESSs. They have an IEC 60664-1 degree of pollution rating
The Phoenix Contact pluggable battery pole connectors are colour-coded and mechanically keyed to prevent cross-wiring and can be simply plugged into the touch- protected socket where they click into place and lock into position (Figure 3). Further simplifying and speeding installation, the connectors can be rotated up to 360˚ as needed. The use of these battery pole connectors can save three-quarters of the typical installation time needed when compared to using lug connectors. A typical industrial or commercial battery rack can have 10 to 12 modules, while a utility-scale BESS installation in a container has hundreds or thousands of battery modules. In such applications, the installation time and cost savings from using specially designed battery pole connectors compared with lug connectors is substantial.
These pluggable battery pole connectors feature low contact resistance and support
Figure 2: Pluggable battery pole connec- tors for BESS overcome the limitations of lug connectors and meet the performance demands of consumer, industrial and utility installations. (Image source: Phoenix Contact).
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