A Conventional Ideal 22-kVA, 2400/240 V Distribution Transformer to Autotransformer Calculation

Calculating Nominal Rating of Autotransformer

A conventional ideal 22-kVA, 2400/240 V distribution transformer is to be connected as a 2640/2400 V ideal autotransformer. To find the nominal rating of the autotransformer in kVA, we can apply the formula:

Nominal Rating of Autotransformer = (V1 * Conventional Transformer kVA Rating) / V2

Where:

V1 = Primary Voltage of Autotransformer (2640 V)

Conventional Transformer kVA Rating = kVA Rating of Conventional Transformer (22 kVA)

V2 = Secondary Voltage of Autotransformer (2400 V)

Calculation

Given V1 = 2640 V, Conventional Transformer kVA Rating = 22 kVA, and V2 = 2400 V

Nominal Rating of Autotransformer = (2640 V * 22 kVA) / 2400 V = 24.4 kVA

Final Answer

The nominal rating of the 2640/2400 V ideal autotransformer, once a 22-kVA, 2400/240V distribution transformer, is effectively 24.4 kVA.

Explanation

The problem involves an autotransformer, which is a transformer with a common winding serving as both primary and secondary sides. The question seeks the nominal rating of an autotransformer that was previously a 22-kVA, 2400/240V distribution transformer.

For this calculation, the formula (V1 * conventional transformer kVA rating) / V2 was employed. Substituting the given values, we arrived at a nominal rating of 24.4 kVA for the autotransformer.