E91 vs Vertiv Liebert EXS
The Xtreme Power E91 Series and the Vertiv Liebert EXS are compact three-phase online double-conversion UPS platforms with internal VRLA batteries for 208/120V applications. Both deliver true online protection; they differ in platform scalability, system density, installation logistics, and lifecycle ownership. The E91 scales from 10 to 40 kVA within one cabinet strategy — where the Liebert EXS is commonly deployed in the 10–20 kVA range — and differentiates on defined internal runtime, lower installed weight, standard integrated maintenance bypass, and broader standard warranty.
Where the E91 leads
- Scalable compact three-phase deployment up to 40 kVA within one cabinet strategy — versus the EXS’s typical 10–20 kVA range.
- Defined internal runtime configurations at full rated load.
- Lower installed system weight, simplifying logistics.
- Integrated maintenance bypass as standard.
- Broader standard warranty coverage.
Compact three-phase UPS, side by side
| Specification | Xtreme Power E91 Series | Vertiv Liebert EXS | Advantage |
|---|---|---|---|
| Capacity range (compact architecture) | 10–40 kVA | 10–20 kVA | Larger deployments, no platform change |
| Voltage scope | 208/120V three-phase | 208/120V three-phase | Direct electrical match |
| Battery chemistry | Internal VRLA | Internal VRLA | Comparable technology |
| UPS topology | Online double-conversion | Online double-conversion | Equivalent conditioned power |
| System footprint | Compact integrated cabinet | Larger, configuration-dependent | Higher density |
| System weight | Lower installed weight | Higher installed weight | Easier logistics |
| Maintenance bypass | Integrated standard | External / optional | Simplified service continuity |
| Runtime scalability | External battery cabinet support | Modular runtime expansion | Comparable long-runtime flexibility |
| Warranty coverage | Broader standard coverage | Standard manufacturer coverage | Ownership advantage |
| TAA compliance | TAA compliant | TAA available | Comparable procurement eligibility |
Specifications are based on publicly available manufacturer documentation; deployment configurations vary by project design. Both are true online double-conversion three-phase UPS with internal VRLA batteries and comparable TAA eligibility. The E91 supports a larger 10–40 kVA range in one cabinet strategy and differentiates on defined internal runtime, lower installed weight, standard integrated maintenance bypass, and broader standard warranty. Confirm current Vertiv Liebert EXS specifications against vendor documentation.
Choosing between them
Both deliver online double-conversion protection with internal VRLA batteries for 208/120V three-phase loads. Choose the E91 for scalable capacity up to 40 kVA in one cabinet strategy, defined internal runtime, lower installed weight, and broader warranty; the Liebert EXS fits within the 10–20 kVA range where an existing Vertiv standard governs.
Choose the E91 Series if you need
- Scalable capacity up to 40 kVA in one cabinet strategy
- Predictable defined internal runtime at full rated load
- A compact footprint and lower installed weight for distributed electrical rooms
- Integrated maintenance bypass as standard
- Broader standard warranty coverage
- TAA-compliant procurement
The Liebert EXS may fit if you need
- An existing Vertiv Liebert EXS standard governs the facility
- Deployments stay within the 10-20 kVA range
- Modular runtime expansion is the preferred approach
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.