15 kVA 208/120 V Three-Phase Online UPS Comparison
Compact three-phase UPS systems are widely deployed in healthcare, education, retail, and distributed IT environments requiring reliable double-conversion protection, efficient operation, and manageable installation footprint. The Xtreme Power E91 15 kVA and Eaton 9355 15 kVA are online double-conversion UPS systems designed for 208/120 V three-phase applications.
Both platforms provide robust power protection and integrated maintenance bypass capability. However, key differences exist in usable real-power output, operating efficiency, physical footprint, system weight, runtime performance, and standard ownership coverage.
The E91 15 kVA delivers full 15 kW output at unity power factor, higher operating efficiency, and a smaller, lighter cabinet. The Eaton 9355 provides comparable topology but reduced usable output at 13.5 kW and a larger, heavier chassis.
For facilities prioritizing maximum usable capacity, compact footprint, and simplified ownership, the E91 15 kVA provides a more efficient and space-optimized solution.
Learn more about the Xtreme Power E91 Series
https://xpcc.com/products/e91/
Key Differentiators at a Glance
- Full 15 kVA / 15 kW usable output (unity power factor)
• Higher operating efficiency
• Smaller vertical footprint
• Significantly lighter system weight
• Competitive runtime at higher real load
• Factory start-up included as standard
• Longer standard electronics warranty
15 kVA Three-Phase UPS Feature Comparison
208/120 V Applications
| Feature | Xtreme Power E91 15 kVA | Eaton 9355 15 kVA | Notes / Considerations |
| Rated Capacity | 15 kVA / 15 kW | 15 kVA / 13.5 kW | Full real-power output (unity PF) |
| Output Power Factor | 1.0 | 0.9 | More usable kW from same kVA |
| UPS Topology | Online double conversion | Online double conversion | Comparable protection architecture |
| Efficiency (Online) | 94% | 91% | Higher efficiency reduces energy and cooling |
| Maintenance Bypass | Standard (integrated) | Standard (integrated) | Both allow seamless service |
| Size (W × D × H) | 11.9 × 34 × 40.2 in | 12 × 33.5 × 47.8 in | Smaller vertical footprint |
| Weight (with batteries) | 504 lb | 609 lb | Significantly lighter system |
| Internal Runtime | 11 min @ 15 kW | 13 min @ 13.5 kW | Higher real-load runtime |
| Runtime Expansion | External battery cabinets | External battery cabinets | Comparable scalability |
| Warranty (Electronics) | 2 years | 1 year parts | Longer standard coverage |
| Start-up & Labor | Factory start-up included | Start-up optional; 90-day labor | Lower deployment cost |
| TAA Compliance | TAA compliant | TAA compliant | Eligible for federal procurement |
Download the Printable Comparison
Download the Xtreme Power E91 15 kVA vs Eaton 9355 comparison PDF
Ideal for engineering submittals, bid reviews, and procurement evaluations.
https://xpcc.com/wp-content/uploads/Xtreme-E91-15k-Eaton-9355-Comparison.pdf
Where the E91 15 kVA Excels
- Facilities requiring full 15 kW usable output
• Installations with limited vertical clearance
• Deployments seeking higher operating efficiency
• Projects requiring lighter equipment placement
• Applications needing runtime at full real load
• Specifications requiring longer electronics warranty
• Federal projects requiring TAA compliance
When the Eaton 9355 May Be a Fit
- Facilities standardized on Eaton infrastructure
• Installations aligned with existing 9355 deployments
• Sites using established Eaton service programs
Who Should Choose Which?
Choose the Xtreme Power E91 15 kVA if you need:
- Full 15 kW usable capacity
• Smaller and lighter UPS footprint
• Higher operating efficiency
• Runtime at full rated load
• Factory start-up included
• Longer standard electronics warranty
Choose the Eaton 9355 if you need:
- Alignment with existing Eaton deployments
• Standardization with 9355 infrastructure
• Eaton service ecosystem continuity
Compare E91 15 kVA to Other Compact 3-Phase UPS Alternatives
Evaluating compact three-phase UPS platforms or planning multi-site standardization?
View all E91 Series comparisons:
https://xpcc.com/e91-ups-comparisons/
Plan With Confidence
Xtreme Power Conversion supports specification development, runtime planning, and three-phase UPS deployment for healthcare, education, retail, and distributed IT environments.
(800) 582-4524
sales@xpcc.com