Transformer Vector Groups

Definition: The transformer vector group show the phase difference between the primary and secondary sides of the transformer. The three phase transformer is connected in various ways. On the basis of connection, the vector group of the transformer is determined. Three phase transformer is divided into four main groups according to the phase difference between…

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Three-Phase Transformer Construction

A three phase transformer is used to transfer a large amount of power. The three phase transformer is required to step-up and step-down the voltages at various stages of a power system network. The three phase transformer is constructed in two ways. Three separate single phase transformer is suitably connected for three phase operation. A…

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Three-Phase Transformer Connections

The three phase transformer consists three transformers either separate or combined with one core. The primary and secondary of the transformer can be independently connected either in star or delta. There are four possible connections for a 3-phase transformer bank. Δ – Δ (Delta – Delta) Connection Υ – Υ (Star – Star) Connection Δ…

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Electrical Transformer

Definition: The electrical transformer is a static device which consists of two or more stationary electric circuits interlinked by a common magnetic circuit for the purpose of transferring electrical energy between them. The transfer of energy from one circuit to another take place without a change in frequency. Construction and Working of an Electrical Transformer…

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Transformer Winding Resistance

The ideal transformer has no resistance, but in the actual transformer, there is always some resistance to the primary and secondary windings. These resistances are shown external to the windings in the figure below. For making the calculation easy the resistance of the transformer can be transferred to the either side. The resistance is transferred…

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Step-up & Step-down Transformers

Step-up Transformer A transformer in which the output (secondary) voltage is greater than its input (primary) voltage is called a step-up transformer. The step-up transformer decreases the output current for keeping the input and output power of the system equal. Considered a step-up transformer shown in the figure below. The E1 and E2 are the…

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Scott-T Transformer Connection

Definition: The Scott-T Connection is the method of connecting two single phase transformer to perform the 3-phase to 2-phase conversion and vice-versa. The two transformers are connected electrically but not magnetically.One of the transformers is called the main transformer, and the other is called the auxiliary or teaser transformer. The figure below shows the Scott-T…

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Three-winding Transformer

Definition: Sometimes in high rating transformer, the third winding is constructed in addition to the primary and the secondary windings. The third winding is called the tertiary winding, and because of the three windings, the transformer is called the three-winding transformer. The voltage ratings of all the three windings of the transformer are usually unequal.The…

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Harmonics in Three Phase Transformers

The harmonic is the distortion in the waveform of the voltage and current. It is the integral multiple of some reference waves. The harmonic wave increases the core and copper loss of the transformer and hence reduces their efficiency. It also increases the dielectric stress on the insulation of the transformer. In a three-phase transformer,…

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Transformer Inrush Current

Definition: The transformer inrush current is the maximum instantaneous current drawn by the primary of the transformer when their secondary is open circuit. The inrush current does not create any permanent fault, but it causes an unwanted switching in the circuit breaker of the transformer. During the inrush current, the maximum value attained by the…

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