Kilovolt-amperes, kilovolt-amperes (kVA) = kilowatts (KW), 1W = 1V x 1A.
Generally speaking, because the KVA is an "apparent power", which is the sum of the active and reactive power, so if the line is purely resistive loads, the "total power" can be the same as the transformer kVA.
In general, because KVA is the "apparent power", it is the sum of active and reactive power, so if the line is purely resistive loads, then the "total power" and the transformer kVA number is the same; but because the line generally have inductive loads, the power factor is impossible to reach 1. Therefore, it can be taken with the load rating must be smaller than the transformer kVA number in order to meet the requirements.
Kilovolt-ampere:
Kilovolt-ampere (kVA) is a unit of capacity of electrical equipment (e.g., transformers, motors, etc.). In an AC circuit, voltage (kV) * current (A) = capacity (kVA). The capacity size of a transformer is expressed in kilovolt-amperes. Rated capacity is the customary value of the apparent power under the main tap.
The capacity specified on the nameplate of the transformer is the rated capacity, which refers to the tap changer is located in the main tap, is the product of the rated no-load voltage, rated current and the corresponding phase factor. For three-phase transformers, the rated capacity is equal to = 3 × rated phase voltage × phase current, rated capacity is generally expressed in kVA or MVA.
And the actual output capacity for the voltage when there is a load (inductive load, the load voltage is less than the rated no-load voltage), the rated current and the corresponding coefficient of the product. The kilowatt is the power of an electrical appliance, which is the unit of power. Rated capacity indicates the guaranteed value of transformer output power under rated operating conditions, is the apparent power of the transformer.
That is, the ability of the transformer to output the maximum electric power, the actual output power of the transformer can not be confused with the capacity. Unit for volt-ampere (VA), kilovolt-ampere (kVA), megavolt-ampere (MVA).
Common units in the power system are: volt-ampere is the unit of total power; watt is the unit of active power; total power * efficiency = active power; kilovolt-ampere kVA is the apparent power; which includes active and reactive power; kilowatt kW is the active power; kilowatts (kW) = kilovoltaic ampere (kVA) multiplied by the power factor.
Kilovolt-ampere (kVA) is apparent power, which is the capacity of the equipment (usually a transformer); kilowatts (kW) kW is active power, which refers to the active power consumed by your equipment (usually power equipment); and there is also a reactive power, Qvar, which refers to the power consumed by the inductive loads in the equipment.
Reference for the above:Baidu Encyclopedia - kVA