Friday 10 November 2017

TRANSFORMER-BASICs

BASIC DEFINITIONS :

Transformer is a static device which is used for transferring the electric power from one circuit to another circuit without changes in the frequency and it accomplishes this by electromagnetic induction or mutual inductance.

  • The transformer has no rotating part so it is called static device.
  • Transformer is a electromagnetic device designed for the transform of alternating current in to another one without changes in the frequency.
  • Transformer with two winding's is called double-winding transformer and three or more winding's is termed is called multi-winding one.
  • A tapped transformer is one whose winding's fitted with special taps for changing voltage.
step-up transformer:
A transformer raises the voltage level from the input voltage is called step-up transformer.
step-down transformer:
A transformer reduces the voltage level from the input voltage is step-down transformer.

Auto transformer:
A transformer in which part of the winding is common to both the primary and secondary circuit is known as an auto transformer.
kind of transformers:
power transformer:
It should be designed have maximum efficiency at near or full load.
This type of transformer used for the transmission and distribution of electric power.
Auto transformer:
This type of transformer used for converting voltages within relatively small limits to connects power system of different voltages,to start AC motors etc,.
Radio transformer :
It is used in radio engineering.
Distribution transformer:
In this type transformer used only distribution sides.It should be designed to have maximum efficiency at a load much lower than full load.
Testing transformer:
In this type of transformer conducts tests at high and ultra high voltages.
Transformation ratio :
Transformation ratio of transformer is secondary voltage to primary voltage is known as transformation ratio.
Transformer specification:
1.kva ratings
2.Rated voltages
3.Number of phase(1 or 3 phase)
4.Rated frequency
5.connections
6.Type of core
7. Tappings if any.
8.Type of transformer(power or distribution)
These are all above particulars must present in the name plate details of transformer.

The efficiency of transformer will be maximum when 
               Copper losses  = iron losses
dielectric strength of the transformer oil is expected to be 33 kv.
Transformer Losses:
The losses in a transformer are classified as follows
 1.Iron losses (It includes hysteresis and eddy current losses)
 2.Copper losses
Transformer Tests:
The transformer test are classified as follows 
1.open circuit or no load test
2.short circuit or Impedance test



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