Guides
Three-Phase UPS Guides
Plain-English guides to specifying, sizing and running three-phase UPS systems, written by engineers who supply and service every major brand. Pick a topic.
Double conversion or line-interactive: what three-phase models actually use
A double-conversion (online) UPS turns incoming AC into DC and back into AC all the time, so the load is always fed by the inverter; a line-interactive UPS feeds the load from the utility through a regulator and switches to its inverter only when the supply fails. Every current three-phase family in the table below is double conversion; what separates them is the high-efficiency mode each adds and the efficiency each manufacturer quotes.
Sizing a three-phase UPS: what each current model covers
Sizing a three-phase UPS means finding a model whose frame covers your end-state load in kW, at your voltage, with room for redundancy. Check the kW rating, not only the kVA: Eaton lists the 9355 at a 0.9 output power factor, so a 30 kVA 9355 delivers 27 kW, while the APC Galaxy VS, Vertiv Liebert APM2 and XPC M90U are rated kW for kVA.
How long does a three-phase UPS battery last?
Short answer: most three-phase UPS battery strings reach end of useful life in three to five years, not the “ten-year” number printed on the cell. Heat, depth of discharge and age decide how close you get, and here is how to read the signs.
UPS redundancy: N, N+1 and 2N by three-phase model
UPS redundancy counts spares against N, the capacity the critical load needs. N+1 holds one module or unit more than N, so one can fail or be serviced on line. 2N builds two complete UPS systems on separate paths, each able to carry the load alone, and 2(N+1) gives each of those systems its own spare.
UPS and generator sizing and compatibility
A generator and a UPS do two different jobs. Get the sizing and the settings right and they hand the load back and forth cleanly, get them wrong and the genset trips the moment the UPS picks up.
Static bypass vs maintenance bypass in a three-phase UPS
A static bypass is an automatic, solid-state path inside the UPS that moves the load to the bypass supply when the inverter fails, is overloaded or is shut down. A maintenance bypass is a manual breaker path around the UPS that keeps the load powered while the UPS is isolated for service. Both paths feed the load unconditioned power.
Modular or monolithic: how current three-phase UPS models are built
A modular three-phase UPS holds several swappable power modules in one frame, so capacity and N+1 redundancy grow by adding modules; a monolithic UPS has one fixed power section and grows by paralleling whole units. Among current models, the APC Galaxy VL, Eaton 93PM, Vertiv Liebert APM2, Delta DPH and XPC M90U are modular, while Vertiv describes the Liebert EXL S1 and Toshiba the G9000 as monolithic.
Three-phase UPS commissioning: what each manufacturer includes
Commissioning a three-phase UPS is the on-site start-up and test sequence that proves the installed system before it carries the load. For many current models the manufacturer ties start-up to its own service: Schneider includes a 5x8 start-up in the part numbers of the Galaxy VS, VL, VX and Easy UPS models we list, and Eaton includes start-up on the 93PM and 9395 family and defines it as work by an Eaton engineer or agent.
Three-phase UPS preventive maintenance, across Canada
A UPS only proves itself during a power cut. Preventive maintenance is how you make sure it will, on one unit or a fleet spread across the country.
Replace the batteries, or the whole UPS?
Flat batteries don’t always mean a new UPS. Often a battery replacement, sometimes with an extra cabinet for more runtime, is the cost-effective fix. Here’s how to tell.
Replacing a discontinued three-phase UPS: dates and named successors
A discontinued three-phase UPS is no longer sold, but it usually stays serviceable until the manufacturer's end-of-service date, and the replacement starts from the successor the manufacturer names. Schneider, for example, discontinued the MGE Galaxy 7000 500 kVA on August 29, 2023, lists end of service on December 31, 2031, and points to the Galaxy VL; the table below gives the same dates and successors for each discontinued family we track.
Single-phase or three-phase UPS: where the three-phase models start
A single-phase UPS takes and delivers one phase plus neutral; a three-phase UPS takes and delivers three phases. Current three-phase ranges start small: the Vertiv Liebert ITA2 at 5 kVA, the Eaton 93PS at 8 kW, and the Eaton 9355, APC Easy UPS 3S and Eaton 93PM at 10 kVA or kW. Some makers also sell 3:1 versions, three-phase in and single-phase out, such as the Eaton 91PS.
Transformer or transformerless: what current three-phase UPS models use
A transformerless (transformer-free) UPS converts power with IGBT electronics alone, with no isolation transformer in the power path; a transformer-based UPS adds one at the input, the output or both. Many current three-phase families are transformer-free, among them the Vertiv Liebert APM2 and EXL S1, the Mitsubishi 9900AEGIS and the ABB DPA 250 S4, and transformers now appear mainly as voltage options, such as the input isolation transformer on the Eaton 9355 and Tripp Lite S3M at 480 V and 600 V.
UPS harmonics and power factor: what each three-phase model publishes
Input current THD (THDi) measures the harmonic distortion a UPS rectifier draws from the supply, and input power factor how much of that current does useful work. Current three-phase UPS publish THDi from under 1.5% (Socomec MODULYS GP) to 5% (Eaton 9355), most often under 3 to 5% at full load, with input power factor around 0.99 or better.
Eaton 93PM vs APC Galaxy VS vs Vertiv Liebert APM2
The Eaton 93PM, APC Galaxy VS and Vertiv Liebert APM2 are all current modular double-conversion three-phase UPS. At 208 V the 93PM covers 10 to 200 kW, the Galaxy VS about 10 to 150 kW depending on voltage, and the APM2 10 to 150 kVA/kW, rising to 600 kVA/kW at 480/415 V. All three reach about 99% in their high-efficiency modes, so the choice comes down to the range you need at your voltage, the battery set-up and who will service it.
What Drives the Cost of a 20 kW Three-Phase UPS in Canada
Four things set the cost of a 20 kW three-phase UPS: the unit class (a compact unit with internal batteries or a modular frame), the battery runtime, the redundancy (N or N+1) and the installation. We quote each project: send your load, voltage and runtime target and you get a written quote within 4 business hours.
Which three-phase UPS models come in 600 V?
Among the three-phase UPS we checked against manufacturer pages on October 3, 2026, the Eaton Power Xpert 9395P (200 to 1,200 kW) is offered as a native 600 V UPS, and Eaton says it removes the need for an external transformer. The Eaton 9355 (10 to 30 kVA) and the Tripp Lite (Eaton) SmartOnline S3M (10 to 100 kVA) reach 600 V with an input isolation transformer supplied with the UPS, and the discontinued Mitsubishi 9800A came with 480 V and 600 V output options.
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