Power Tip 2: How to Avoid Overloading Phases

Posted by Isaiah LaJoie on July 30, 2020


To address the needs of its customers during the quarantine, Server Technology has designed a webinar series that breaks down the ins and outs of remote power management.  The interactive webinar series, “PowerTips Live,” was developed to support you and your team. Live demonstrations of intelligent PDU features are available to help you better manage your operation remotely. This article is a recap of the second tip in the series, which addresses load balancing on intelligent PDUs, or IP power strips.

While three-phase PDUs provide higher power capacities, they also require planning before server deployment. An unbalanced power draw on one or two of the three phases of the PDU creates stranded capacity which increases wasted electricity. Additionally, this scenario can lead to a cascading failure condition upstream.

Server Technology Intelligent PDUs actively monitor balancing between phases and, if configured correctly, can alert you or your team when phases are unbalanced beyond a certain threshold. As a best practice, it is important to have all three phases as balanced as possible to minimize unanticipated disruptions and wasted electricity.

To achieve proper load balancing within a Server Tech network PDU, it is best to keep an eye on loads at three different levels: lines, branches, and outlets.  Line notification is about knowing what is going on upstream of the PDU; in other words, what impacts the circuit breaker protecting the PDU itself.  Branches are a group of receptacles on the PDU, and branch-level thresholds allow you to understand loading within a portion of the intelligent PDU.  Outlet-level monitoring allows you to configure each individual outlet on the PDU.

You can get visual feedback immediately by logging into a POPS1 or POPS2 interface on your network PDU.  Within the monitoring menu, immediately under ‘Overview,’ you will find a link to the Monitoring page, which shows all of the monitored points in a dropdown list.  A good place to start is on the Line page.  The Line page shows the current capacity of each line – 3 lines for three-phase PDUs, and 1 line for single-phase PDUs.

When you look at the capacities at any level — whether it be at line, branch, or circuit — it is important to note that the default capacity is 80% per NEC, and that 70% is the threshold at which you will begin getting alerts warning that you are approaching capacity.  Please note that if your intelligent PDUs are in a redundant configuration, you will need to reset the thresholds by dividing them by 2, or a 35% threshold warning with a 40% limit.  This will ensure that you have enough capacity to support the load on the other PDU if it fails over to the unit in question.

If you need further support, we at Server Technology are here to take your calls.  For more details on how to avoid overloading the phases in 3-phase PDU, check out the Power Tip #2 video on YouTube. Check out our first tip on receiving alerts if you missed it, or go to our next tip on configuring notifications and thresholds.

Power Tip 3: Configuring Notifications & Thresholds