The capacity part of the transformer is KVA instead of KW. VA or KVA is the apparent power, used in AC lines, also known as the capacity, which is the product of the rms value of the voltage and the current in volts ampere (VA). It is mostly used in designing lines and equipment.
Because the circuit loads are capacitive loads, some inductive loads, will produce reactive power, reactive power does not consume energy, but will affect the load design of the transformer, so use VA or KVA to calculate more accurately.