... is optional ,8) 230 / 400V AC, 50Hz / 60Hz, 0.8pF three-phase and four wires alternating current output 9) Frequency: <3% ,10) ... Frequency at stable state: <0.5% 11) Frequency deviation ... over current B) Operation display: I) Unit voltage, tri-phase load current and frequency display Ii) Water temperature, oil ...