Answering Specifiers’ FAQs on Busway Design
🕓 5 minute read | Chris Osian, Product Manager at Starline
During our recent How to Design Flexible Power Architectures for AI, High-Density Data Centers webinar with Consulting-Specifying Engineer, attendees submitted a range of questions about designing scalable, reliable power distribution for high-density data center environments. In this blog, Starline Product Manager Chris Osian, answers some of the most common questions raised during the session.
1. Can plug-in metering be added to busway systems?
Plug-in metering can be added at both the plug-in unit and end feed level. As AI and HPC power densities continue to rise, monitoring at the branch circuit level has become increasingly important. It provides operators with real-time visibility into voltage, current, power, and overall load behavior throughout the distribution system.
Starline’s M70 Critical Power Monitor (CPM) communicates data in real-time to BMS and DCIM platforms. In addition to providing critical load data, plug-in metering adds an additional layer of protection for personnel and equipment. Temperature monitoring and alarm capabilities can help identify abnormal conditions or early indicators of overheating, allowing operators to respond before issues become safety risks or cause downtime.
2. What is the difference between busway and busduct in data center applications?
Although the terms busway and busduct are sometimes used interchangeably, they refer to different types of power distribution systems.
Busduct is a fully enclosed system with fixed tap-off locations. It is commonly used in applications requiring high amperages, often exceeding 1500A. Busway is an open channel system that allows plug-in units to be installed anywhere along the run. This provides greater flexibility for evolving data center layouts. For example, Starline Track Busway allows plug-in units to be added or hot-swapped in the field, making it easier for operators to scale as power requirements evolve.
3. Can Starline busway be specified with higher ingress protection for liquid-cooled environments?
Starline offers an IP54-rated busway solution designed for environments that require additional protection against dust and liquid exposure. While IP2X is sufficient for most traditional data center white space applications, the introduction of liquid cooling has increased the demand for higher ingress protection. Starline’s Series-S busway addresses these evolving requirements while maintaining the flexibility and scalability of traditional track busway.
4. What options are available to limit fault current to rack-mounted PDUs, given that their short-circuit ratings are significantly lower than the busway system?
Overcurrent protection devices (OCPDs) play a critical role in limiting available fault current and protecting downstream equipment such as rack-mounted power strips or PDUs. The two primary current-limiting devices used in data center power architectures are fuses and circuit breakers. Both reduce fault energy, but they operate differently with tradeoffs.
While many facilities rely on circuit breakers, rising power densities have led hyperscale operators to implement current-limiting fuses. Fuses have faster clearing times than circuit breakers, which can reduce incident energy and enhance arc flash protection in high-density environments. However, fuses must be replaced after operation, whereas circuit breakers can be reset. In addition to selecting the appropriate OCPD, implementing selective coordination can further help to protect equipment and minimize the scope of potential incidents. To learn more about OCPDs, read our arc flash safety white paper.
5. How can Starline busway systems be designed to reduce arc-flash risk?
Starline busway offers a range of solutions designed to mitigate arc flash risk in high-density environments. Current-limiting fuses provide downstream protection by interrupting fault current and reducing incident energy during electrical events. The Remote Plug-In Actuator (RPA) adds an additional layer of safety during live insertions by allowing personnel to engage or disengage plug-in units from outside the arc flash boundary.
Additional tools such as infrared (IR) windows and integrated thermal monitoring help identify hot spots and abnormal temperature conditions. Together, these solutions are designed to enhance personnel safety, support system reliability, and reduce the risk of downtime. To learn more about Starline’s safety solutions, visit our safety hub.
6. What is the day-one cost difference between busway and RPP-based power distribution?
Busway offers measurable Day 1 cost advantages compared to traditional Remote Power Panels (RPPs). By simplifying installation and reducing labor, overhead busway lowers the total installed project cost.
To illustrate this, Starline modeled a 28-rack row with 400A A/B redundancy using both a conventional RPP layout and a busway design. The cost comparison shows that busway offers financial advantages in installation labor and total project cost. To see the full cost comparison, click here.
To learn more about how busway compares to RPPs, visit our webpage for a full head-to-head comparison.