P91 Online UPS – Scalable Runtime Rack/Tower UPS (1000–3000VA, 120V)
1000–3000 VA | 120V | Online Double-Conversion UPS
Runtime-flexible online UPS engineered for distributed IT, AV, retail, and multi-site infrastructure requiring continuous power conditioning and scalable runtime.
1000–3000 VA · 120VAC · Online Double-Conversion UPS · Scalable Runtime
P91 online UPS with scalable runtime
The P91 is a 120 V online double-conversion UPS built around a flexible VRLA battery architecture: internal batteries provide standard ride-through, while external battery packs extend runtime to match the application. Online topology continuously conditions incoming power with zero transfer time, and near-unity power factor (2U units) delivers maximum usable watts — all in a compact 2U rack/tower form factor (plus a 1U model). It is TAA compliant (made in Taiwan; UL / cUL listed) for federal, education, and public-sector procurement. For a lithium alternative, see the P91 Li.
Scalable-runtime online UPS architecture
Unlike fixed-runtime platforms, the P91 is built around a flexible battery architecture. Internal batteries provide standard ride-through, while external battery packs extend runtime based on application requirements — so runtime is engineered per deployment rather than constrained by internal capacity. Online double-conversion topology continuously conditions incoming power, isolating equipment from voltage disturbances, frequency variation, and electrical noise, and maintains zero transfer time during outages.
What the P91 delivers
Zero transfer time and continuous conditioning – pure sine output at ≤2% THD (linear) / ≤4% THD (non-linear) on 2U units.
Add up to seven matching packs (BP36 / BP48 / BP72) to take a rack from a few minutes of ride-through to over two hours — enough to outlast most outages or bridge to a generator — then recharge to 95% in under 3 hours.
2U units deliver near-unity output power factor — up to 1450 W from a 1500 VA frame, more usable watts than the 1350 W typical of competing online units.
An adjustable charger (up to 8 A) quickly recharges internal batteries and up to seven external packs; recharge to 95% in under 3 hours.
An optional XBDM bypass lets you service or swap the UPS without dropping the rack; after a full discharge, auto-restart brings the load back the moment utility returns — no truck roll to power-cycle.
Up to 98% ECO-mode efficiency, with optional Web/SNMP, Modbus, and relay/dry-contact monitoring cards.
The standard online UPS with scalable runtime
The P91 operates as the standard online UPS platform within distributed power architecture, providing conditioned power and scalable runtime at the rack or edge level. It is typically deployed in network closets, IDF/MDF environments, and multi-site infrastructure where runtime requirements vary but platform standardization is required.
Choose the P91 for online protection with VRLA runtime scaled per deployment and the lowest upfront cost; step up to lithium (P91 Li or J90) for reduced maintenance and longer lifecycle, or down to the line-interactive P80 / S71 where full-time conditioning isn’t required.
P91 (VRLA) or lithium?
The P91 is a VRLA-based platform optimized for runtime scalability and lower initial cost — ideal when extended-runtime requirements and budget outweigh lifecycle optimization. Lithium platforms such as the P91 Li and J90 prioritize lifecycle performance, reduced maintenance, and higher density. Both deliver full-time online conditioning; the choice comes down to runtime strategy and total cost of ownership.
P91-1500 vs the field at 1.5 kVA
The differences are clearest at a single capacity. Here is the P91-1500 against the 1.5 kVA online platforms it most often replaces, drawn from the per-model comparisons. The 1, 2, and 3 kVA matchups follow the same pattern — full breakdowns are in the comparison hub.
| Feature (1.5 kVA) | Xtreme P91-1500 | APC SRT1500XLA | Eaton 9PX1500RT | Vertiv GXT5-1500 |
|---|---|---|---|---|
| Topology | Online double-conversion | Online double-conversion | Online double-conversion | Online double-conversion |
| Real power | 1450 W | 1350 W | 1350 W | 1350 W |
| UPS depth | 16.1 in | 20.0 in | 17.7 in | 18.6 in |
| Warranty (electronics / battery) | 3 yr / 3 yr | 3 yr / 2 yr | 3-year | 3 yr / 3 yr |
| TAA compliant | Yes | No | No | Optional SKU |
The P91-1500 leads on usable watts (1450 W vs 1350 W), shallower depth (16.1 in — the smallest here), full 3-year battery warranty, and standard TAA compliance. Tripp Lite and WattBox matchups are in the hub. All P91 comparisons →
Five models, 1000–3000 VA
| Model | Capacity | Form factor | Receptacles | Dimensions (W×D×H) | Weight | Internal battery |
|---|---|---|---|---|---|---|
| P91c-1000 | 1000 VA / 800 W | 1U | (3) NEMA 5-15R | 17.2 × 17.8 × 1.7 in | 28 lb | (4) 6V 290W |
| P91-1000 | 1000 VA / 1000 W | 2U | (8) NEMA 5-15R | 17.2 × 15.1 × 3.5 in | 25.5 lb | (2) 12V 9Ah |
| P91-1500 | 1500 VA / 1450 W | 2U | (8) NEMA 5-15R | 17.2 × 15.1 × 3.5 in | 34.2 lb | (3) 12V 9Ah |
| P91-2000 | 2000 VA / 1930 W | 2U | (8) NEMA 5-15/20R | 17.2 × 19.0 × 3.5 in | 43 lb | (4) 12V 9Ah |
| P91-3000 | 3000 VA / 2880 W | 2U | (1) L5-30R + (6) 5-15/20R | 17.2 × 23.8 × 3.5 in | 60.6 lb | (6) 12V 9Ah |
2U units offer near-unity power factor and selectable output (100/110/115/120/127 VAC). Rack depth is measured front bracket to unit panel; add 1 in for the front bezel. The P91c-1000 is a 1U model with internal batteries only.
Four things that separate the P91 at 1.5 kVA
External battery packs are not one of them. APC, Eaton and Vertiv all offer them in this class, so runtime expansion is table stakes rather than a differentiator. What actually separates the P91 is narrower and more useful.
- TAA compliant, every modelAPC and Eaton are not TAA compliant in this class. Vertiv requires a separate SKU. On a federal, state, education or healthcare contract that is binary: you are eligible to bid or you are not.
