Home / Transformer


Buck-Boost Transformer Working Principle

An isolation transformer can be wired as an autotransformer in a buck configuration

A buck-boost transformer is a type of transformer which is primarily used to adjust the voltage level applied to various electric equipment. Buck-boost transformers are utilized in in several applications such as uninterruptible power supplies (UPS) units for computers. When an existing AC electrical circuit suffers from excessive voltage drop …

Read More »

Three Phase Transformer Construction

2500 kVA power transformer.

A transformer consists of two or more electrical windings that are linked together by a magnetic field. Except for special-purpose transformers, the coupling is enhanced with a ferromagnetic core. Transformers are often drawn as shown in Figure 1, with the primary coil on one leg and the secondary coil on …

Read More »

Autotransformer: Working, Advantages, Disadvantages

Autotransformer Definition The autotransformer has a single winding on an iron core. One of the coil terminals is common to both input and output, and the other output terminal is movable so that it can make contact with any turn on the winding. Step-Up/ Step-Down Autotransformer An autotransformer can be …

Read More »

Three Phase Transformer Connections Phasor Diagrams

Wye-Wye Three-Phase Transformer Connection

Three Phase Transformer Connections A three-phase transformer is built for a specific connection and voltage transformation and the unit will have a nameplate with the internal connections shown. When a single unit or bank of three is used, there are four types of connections. The four basic connections are: Y-Y, Y-∆, ∆-Y, and ∆-∆. …

Read More »

Transformer Nameplate Details Explained

transformer nameplate

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 …

Read More »

Transformer Polarity Test

Transformer Polarity Markings

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 …

Read More »

Transformer Losses and Efficiency Calculation

Complete Equivalent Circuit

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 …

Read More »

Transformer Working Principle | How Transformer Works

A transformer circuit

Transformer Definition A device consisting of two or more windings coupled by a magnetic core that is used to transform a balanced set of three-phase voltages from one voltage level to another without changing the frequency. The transformer is an essential element of an electrical power system. It is among …

Read More »