The correct answer is: C. above 200 kVA.
Power transformers are used to transfer electrical energy from one circuit to another. They are typically rated in kilovolt-amperes (kVA), which is a measure of the transformer’s power capacity. The rating of a power transformer is determined by the following factors:
- The voltage of the input and output circuits
- The current of the input and output circuits
- The efficiency of the transformer
Power transformers are typically rated for voltages of 115, 230, or 480 volts. The current of the input and output circuits is determined by the load on the transformer. The efficiency of a transformer is a measure of how much of the input power is transferred to the output circuit.
The rating of a power transformer is important because it determines the maximum amount of power that the transformer can safely handle. If a transformer is overloaded, it can overheat and fail. Therefore, it is important to select a transformer with a rating that is appropriate for the load.
Option A is incorrect because power transformers can have ratings that are much higher than 50 kVA. Option B is incorrect because power transformers can have ratings that are much lower than 100 kVA. Option D is incorrect because power transformers do have ratings.