E91 20 kVA vs Eaton 9355
The Xtreme Power E91 20 kVA and the Eaton 9355 20 kVA are true online double-conversion UPS systems for 208/120V three-phase applications. The E91 delivers full 20 kW output at unity power factor, higher efficiency, and a dramatically smaller and lighter design; the Eaton 9355 provides longer internal runtime but with substantially larger size and weight and reduced usable output at 18 kW.
Where the E91 20 kVA leads
- Full 20 kVA / 20 kW usable output at unity power factor — vs the Eaton’s 18 kW.
- Higher operating efficiency (94% vs 91% online).
- A dramatically smaller footprint and substantially lighter weight (570 vs 1,160 lb).
- Factory start-up included as standard, plus a longer standard electronics warranty.
20 kVA three-phase UPS, side by side
| Specification | Xtreme Power E91 20 kVA | Eaton 9355 20 kVA | Advantage |
|---|---|---|---|
| Rated capacity | 20 kVA / 20 kW | 20 kVA / 18 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 |
| Dimensions (W × D × H) | 11.9 × 34 × 40.2 in | 20 × 34.1 × 66 in | Dramatically smaller footprint |
| Weight (with batteries) | 570 lb | 1,160 lb | Substantially lighter |
| Internal runtime | 7 min @ 20 kW | 18 min @ 18 kW | Eaton longer, but far larger & heavier |
| 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 20 kW usable output (vs 18 kW), higher efficiency, and a dramatically smaller, lighter cabinet (570 vs 1,160 lb), with factory start-up and a longer warranty. The Eaton provides longer internal runtime, but only with a much larger and heavier chassis. Confirm Eaton 9355 specifications against current Eaton documentation.
Choosing between them
Choose the E91 for full 20 kW usable output, a compact and far lighter cabinet, higher efficiency, factory start-up, and longer warranty; the 9355 fits where maximum base-cabinet runtime is the priority and a much larger, heavier enclosure is acceptable.
Choose the E91 20 kVA if you need
- Full 20 kW usable capacity
- A smaller and lighter UPS footprint
- Higher operating efficiency
- Full-load runtime capability
- Factory start-up included
- Longer standard electronics warranty
The 9355 20 kVA may fit if you need
- Facilities standardized on Eaton infrastructure
- Maximum internal runtime is the priority
- A larger, heavier cabinet footprint is acceptable
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.