What is the largest single phase output UPS available?

20kVA/20kW is the maximum single phase output supply available from most UPS manufacturers. At 230Vac this is 87A at Unity power Factor (pF) and may be available from a 1/1 (single phase input and output UPS) or a 3/1 (three phase input and single phase output) UPS. It is not common to install a 20kVA single phase UPS unless there is a specific load requiring this.