DCMT PRESENTATION DEVANSH KHARE (141043109002) SARTHAK PUROHIT (131040109048) Course code - 2130904

POLARITY TEST AND LOSSES IN TRANSFORMER

TRANSFORMER

TRANSFORMER CONSTRUCTION

IDEAL TRANSFORMER The source side is called Primary The load side is called Secondary Ideally The resistance of the coils are zero. The relative permeability of the core in infinite. Zero core or iron loss. Zero leakage flux

CONDITION FOR POLARITY OF 1-Ø TRANSFORMER 1- Transformer should be properly connected according to their polarities. 2- The voltage ratings and voltage ratios of the Transformer should be same 3- The per unit impedances of the transformers should be equal. 4- The reactance or resistance ratio of the Transformer should be identical.

POLARITY TEST What is Transformer Polarity ? It is an indication of the direction of current flow through the High voltage terminal with respect to the direction of current Flow through the low voltage terminal at any given instant in the alternating cycle . The Polarity of a single phase Transformer may be additive or subtractive .

Transformer polarity Subtractive polarity Additive polarity

What is Additive Polarity of Transformer ? The Polarity is additive if the voltage across the other two leads of the winding is greater than that of the high voltage winding .

What is Subtractive Polarity of Transformer . The polarity is subtractive if the voltage across the other two leads of the winding is less than that of the high voltage winding .

SAME POLARITY OF TRANSFORMER OPPOSITE POLARITY OF TRANSFORMER

LOSSES IN TRANSFORMER -Iron losses ( Constant Losses ) -Cu Losses ( Variable Losses )

COPPER LOSS - The power loss (I2R) in the form of heat in the winding of a Transformer is known as a Copper loss. This losses also known as a Variable loss . IRON LOSS These losses occur in the core of Transformer due to the magnetic field. These losses are practically constant for Transformer . There are Two types of Iron loss in Transformer .

Iron losses Eddy Current Losses Hysteresis Losses

HYSTERESIS LOSS -When a magnetic field is applied all the grains of the magnetic material will orient in the direction of magnetizing force. The energy required to change the orientation of the magnetic grains in the direction of the magnetic field is lost in the form of heat. This loss is called Hysteresis loss.

EDDY CURRENT LOSS When an alternating magnetic flux is applied to the iron core small emf will be induced due to change in flux linkage. This induced emf will cause small circulating current is called eddy currents. Eddy current flowing through the material causes I2R losses in the material.

HOW IDENTIFY THE LOSSES IN TRANSFORMER? There are two types of test which are mention as follows 1 Open circuit test 2 Short circuit test

OPEN CIRCUIT TEST This test is known as a No Load Test. This test is useful to determine ; The no load current I0 and no load power factor Cos ø0 . The magnetic circuit parameter i.e R0 ,X0 ,IW, Iµ . This test is use to find out Iron loss in Transformer.

SHORT CIRCUIT TEST This test is known as a Impedance Test.This test is useful to determine ; Equivalent resistance (R01 & R02), equivalent reactance (X01 & X02 ) and equivalent impedance (Z01 $ Z02) of theTransformer. (2) This test is use to find out copper losses in Transformer.

HOW TO MINIMIZE IRON LOSS MINIMIZE HYSTERESIS LOSS The Hysteresis loss can be minimized:- By using good magnetic material By using less value of Maximum Flux Density (Bm)

MINIMIZE THE EDDY CURRENT LOSS The Eddy current loss can be minimized; By using less thickness of laminations By using less value of Maximum flux Density (Bm)

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