Electrical Machines Lab Experiment #1 Constructional Feature, Transformation Ratio Determination & Polarity Identification of A 1-Transformer
Electrical Machines Lab Experiment #1 Constructional Feature, Transformation Ratio Determination & Polarity Identification of A 1-Transformer
Electrical Machines Lab Experiment #1 Constructional Feature, Transformation Ratio Determination & Polarity Identification of A 1-Transformer
ECE
Apparatus:
Multimeter/ 1- transformer/ 1- AC & DC power supply (variable)/ transformer steel sheet
Theory:
A transformer is a static device which transfers the electrical energy from one circuit to
another circuit without any change in the frequency. The transformer works on the principle
of electromagnetic induction between two windings placed on a common magnetic circuit.
These two windings are electrically insulated from each other and also from the core.
Constructionally the transformers are of two general types, distinguished from each other
merely by the manner in which the primary and secondary coils are placed around the
laminated core. The two types are known as (i) core-type and (ii) shell type.
Identical terminals such as 1 and 3 or 2 and 4 are sometimes marked by dotes or ±. This are
called the polarity markings of the windings. They indicate how the windings are wound on
the core.
If the winding are visually seen, the polarities can be determined. However, usually only the
terminals of the windings are brought outside. Nevertheless, it is possible to determine the
polarities of the windings experimentally.
3. In the simplified diagram of a transformers the primary and secondary winding are shown
located on the opposite legs (or limbs) of the core (fig 2a ) but in actual construction of a
transformer the primary and secondary windings are interleaved (fig 2b )
Why interleaved?
(a) (b)
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DTU
ECE
6. For the given transformer determine the polarities of the windings experimentally
Calculations
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