E91 15 kVA vs Eaton 9355
The Xtreme Power E91 15 kVA and the Eaton 9355 15 kVA are online double-conversion UPS systems for 208/120V three-phase applications. The E91 delivers full 15 kW output at unity power factor, higher efficiency, and a smaller, lighter cabinet; the Eaton 9355 provides comparable topology but reduced usable output at 13.5 kW in a larger, heavier chassis.
Where the E91 15 kVA leads
- Full 15 kVA / 15 kW usable output at unity power factor — vs the Eaton’s 13.5 kW.
- Higher operating efficiency (94% vs 91% online).
- A smaller vertical footprint and significantly lighter weight (504 vs 609 lb).
- Factory start-up included as standard, plus a longer standard electronics warranty.
15 kVA three-phase UPS, side by side
| Specification | Xtreme Power E91 15 kVA | Eaton 9355 15 kVA | Advantage |
|---|---|---|---|
| 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 |
| Efficiency (online) | 94% | 91% | Higher efficiency, less cooling |
| Maintenance bypass | Standard (integrated) | Standard (integrated) | Both integrated |
| 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 |
| Internal runtime | 11 min @ 15 kW | 13 min @ 13.5 kW | Eaton longer, but at 13.5 kW |
| 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 |
Both are true online double-conversion three-phase UPS with integrated bypass and TAA eligibility. The E91 delivers full 15 kW usable output (vs 13.5 kW), higher efficiency, a smaller and lighter cabinet, factory start-up, and a longer warranty. The Eaton shows slightly more raw runtime minutes, but at its reduced 13.5 kW output. Confirm Eaton 9355 specifications against current Eaton documentation.
Choosing between them
Choose the E91 for full 15 kW usable output, higher efficiency, a smaller/lighter cabinet, factory start-up, and longer warranty; the 9355 fits where an existing Eaton standard governs.
Choose the E91 15 kVA if you need
- Full 15 kW usable capacity
- A smaller and lighter UPS footprint
- Higher operating efficiency
- Runtime at full rated load
- Factory start-up included
- Longer standard electronics warranty
The 9355 15 kVA may fit if you need
- Facilities standardized on Eaton infrastructure
- Alignment with existing 9355 deployments
- Eaton service ecosystem continuity
Related comparisons
Standardizing compact three-phase UPS across your facilities?
Xtreme Power supports E91 three-phase UPS sizing, runtime planning with external battery cabinets, modernization strategy for legacy three-phase UPS, and TAA-compliant procurement for healthcare, education, retail, industrial, and enterprise infrastructure.