What Is Phase Balancing?_
Phase balancing is the practice of adjusting the distribution of single-phase and three-phase loads among the three supply phases (A, B, C) so that current draw is as equal as possible. Unbalanced phases can cause neutral current, voltage drops, and transformer overheating. Proper balancing maximizes the usable capacity of the power distribution unit (PDU) and reduces the risk of nuisance breaker trips.
Technical Details
In a three-phase wye system, each phase-to-neutral leg can supply up to the PDU’s rated current per phase; imbalance occurs when one leg carries significantly more load than the others. Field crews measure per-phase current using a clamp meter at the PDU input or rack power strip. Balancing may involve moving server power supplies to different receptacles or swapping PDU input connections to different phases. The goal is to keep per-phase current within 10% of each other, per typical facility guidelines, though exact targets follow the OEM spec or site power policy.
How Leviathan Systems Works with Phase Balancing
During rack assembly and power-up, our field crew checks phase balance at each PDU before GPU nodes are fully loaded, especially for high-power NVL72 racks. We coordinate with the site electrician to re-terminate PDU input feeds if a phase exceeds the acceptable imbalance threshold.
Related service
GPU Rack Assembly & Rack-and-Stack →