Topic — Power Quality
Data Center Harmonics
Data centers concentrate non-linear loads at a scale few other facility types match: UPS rectifiers, variable frequency drives and switch-mode power supplies all draw distorted current. The resulting harmonic currents cause additional heating in transformers, cables and generators, and distort the voltage that every other load on the bus shares.
Harmonic design is a system problem, not an equipment problem. Individual device distortion figures mean little in isolation — what matters is the combined distortion evaluated at the point of common coupling under IEEE 519, and the behavior of the system on generator power, where source impedance is far higher than on utility.
Core engineering questions
- Where is the point of common coupling defined, and what limits apply there?
- What is the combined harmonic contribution of UPS, VFD and IT loads?
- How does voltage distortion change when the facility runs on generators?
- Which mitigation is proportionate: DC chokes, passive filters, active filters, or active front ends?
- Are harmonic requirements written into procurement specifications with a defined evaluation point?
Key design areas
- Harmonic sources: 6-pulse rectifiers, UPS input stages, SMPS loads
- IEEE 519 evaluation methodology and PCC definition
- Mitigation technologies and their trade-offs
- Generator compatibility with non-linear loads
- Harmonic measurement and verification during commissioning
Guides on this topic
ArticleComing soon
Data Center Harmonics: UPS and VFD Interaction
How non-linear loads interact on a shared bus, and what to evaluate at the point of common coupling.
11 min
Design Guide
Variable Frequency Drives in Data Center Cooling Systems
Engineering guidelines for VFD selection, integration, redundancy and operation in mission-critical cooling infrastructure.
15 min
ArticleComing soon
Power Quality in Data Centers
Voltage events, transients, monitoring and mitigation.
10 min