Low-Series Inductance of Copper Bus Bars

This blog is written by a guest contributor.

The guest contributor, Brian J. Inouye, is the President and Founder of Inouye Audio Concepts and a long-time customer of Protocase.

Copper bus bars are popular in electrical systems for their exceptional properties. Their superior electrical conductivity and design flexibility make them a preferred choice. At Protocase, we can build fully-finished custom copper bus bars within a fast 2-3 day manufacturing lead time.

In this blog, we’ll delve into their inherent low-series resistance and low-series inductance, explain why these characteristics matter, and demonstrate how they can enhance the performance of your electrical systems.

The Basics of Current Types: DC vs. AC

To fully understand copper bus bars, it’s important to first examine the two primary types of current used in electrical systems: direct current (DC) and alternating current (AC). Grasping the differences between these currents is crucial for the effective application of bus bars.

• DC Power: Direct current flows consistently in one direction and utilizes the entire cross-section of a conductor, whether it’s a round wire or a flat bus bar. With DC power, the primary design metric to consider is series resistance.
• AC Power: In contrast, alternating current changes direction periodically and primarily flows near the surface of a conductor. This phenomenon, known as the skin effect, results in current flowing mostly on the conductor’s surface rather than through its entire cross-section.

The skin effect varies with frequency and increases effective resistance, impacting both round conductors and flat bus bars. Effective resistance is the combination of series resistance and series inductance.

Importance of Series Inductance in Copper Bus Bars

Series inductance measures an electrical conductor’s ability to store energy in a magnetic field, momentarily resisting current flow. Reducing series inductance improves instantaneous current transfer, resulting in more efficient current flow and less energy loss as heat.

To sum it up, DC power flows through the entire cross-section of a conductor. On the other hand, AC power predominantly flows on the surface.

Even with a conventional linear DC power supply, an AC ripple component exists — 60 Hz for half-wave rectified power and 120 Hz for full-wave rectified power. This is due to periodic fluctuations in the DC voltage output. With switch-mode power supplies, the AC ripple can range from low kilohertz to several megahertz.

Mitigating the Skin Effect with Copper Bus Bars

The low inductance of flat copper bus bars helps mitigate the skin effect by shortening the electrical distance between component connections, which lowers effective resistance. This is especially important in high-power switch-mode power supply applications, where filtering out large high-frequency components is crucial.

For projects involving electrical power components, recognizing the importance of low-series inductance is essential for optimizing system performance. Flat copper bus bars, with their low-series inductance, help minimize losses. This ensures more electrical energy is used for its intended purpose rather than wasted.

Copper vs. Aluminum Bus Bars

Aside from copper, aluminum is a common material used for bus bars. While aluminum is lighter and often more cost-effective, it exhibits higher series resistance and lower electrical conductivity compared to copper.

Copper, along with its low-series inductance, boasts excellent thermal and electrical conductivity, enabling it to handle high current loads without overheating, further enhancing its efficiency.

Conclusion

To wrap things up, copper bus bars are real game-changers in today’s electrical systems. Their low-series inductance means they help reduce energy loss and improve overall performance.

Got a bus bar design ready and need a quote? Just fill out our Request a Quote form! We’ll get back to you with a quote within one business day. Once you finalize and approve your custom design, we can bring your bus bars to life, complete with all of the finishes and markings you need, in just 2-3 days!

Brian J. Inouye

President and Founder, Inouye Audio Concepts