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# Transformer

## Three Phase Transformer Connections Phasor Diagrams

Three-phase transformers are used quite extensively in power systems to transform a balanced set of three-phase voltages at a particular voltage level into a balanced set of voltages at another level. Transformers used between generators and transmission system, between transmission and sub-transmission system, and between sub-transmission and distribution systems are …

## Transformer Nameplate Details Explained

Transformer nameplates contain several standard items of information and other optional information. Transformer nameplate must specify the following parameters: Volt-Ampere (VA) or kilovolt-amperes (kVA) rating The voltage rating of both the primary and secondary circuits The impedance rating of the transformer (normally restricted to 25 kVA or larger) The required …

## Transformer Polarity Test

Transformer windings are marked to identify terminals with the same polarity. Polarity marks may either be dots or + marks. Alternatively, polarity marks may be shown by assigning the same subscripts to corresponding primary and secondary labels, H and X, respectively. Thus, when the primary terminals are named H1 and …

## Transformer Losses and Efficiency Calculation

Transformer Efficiency Definition The efficiency of the transformer is defined as the ratio of the power output Poutput and power input Pinput, both expressed in watts. Thus, $\begin{matrix} \eta =\frac{{{P}_{out}}}{{{P}_{in}}} & {} & \left( 1 \right) \\\end{matrix}$ Or since the input is the output plus losses, \[\begin{matrix}   \begin{align}  & \eta …

## Determination of Transformer Equivalent Circuit Parameters

In order for a model to be useful, there must be a way to determine the values of the model parameters. Two simple tests are used to determine the values for the parameters of the transformer equivalent circuit of Fig. 1 (a) and (b). The two tests are the short-circuit …

## Voltage Regulation of Transformer at Unity, Lagging, and Leading Power Factor

Voltage Regulation of Transformer The voltage regulation of a transformer can be described as the change in the secondary voltage as the current varies from full load to no load while keeping the primary voltage constant. Generally, a transformer is utilized to supply loads that operate at basically constant voltage. …