UPS required for the load of 55 KW at 0.7 power factor or 78.5 KVA
Inverter output = 55 KW
Inverter input(considering 94 % inverter efficiency) = 55/0.94= 58.5 KW
Therefore min. required battery capacity will be 58.5 KW
Selected battery capacity = 70 KW (20% extra)
So, UPS capacity in KVA = 70/0.8 = 87.5 KVA ( Generally UPS are rated at 0.8 power factor)
Nearest standard size available = 100 KVA
So, Select a 100 KVA UPS to feed 55 KW of load at 0.7 power factor