Energy Losses In Transformer. Although transformers are very efficient devices, small energy losses do occur in them due to four main causes: Resistance of windings – the low resistance copper wire used for the windings still has resistance and thereby contribute to heat loss. The eddy currents cause heat loss.
In this manner, how does high voltage reduce energy loss?
Transmission losses are due to current flowing in the conductors. The higher the currents the higher the loss is. So in order to reduce losses and have better efficiency transmission is done at lower currents. Overall power should be same so as power=Voltage*current when the current is low the voltage is high.
The windings of the transformer are made thick so that the resistances are minimised.Another technique is Vaccum Pressure Impregnation(VPI). In this technique the transformer is kept in vaccum then high pressure varnish is passed so that the smallest of the air gaps are also filled. Hence reducing the copper losses.
They include heat losses and eddy currents in the primary and secondary conductors of the transformer. Heat losses, or I 2R losses, in the winding materials contribute the largest part of the load losses. They are created by resistance of the conductor to the flow of current or electrons.
Eddy current loss and hysteresis loss depend upon the magnetic properties of the material used for the construction of core. Hence these losses are also known as core losses or iron losses. Hysteresis loss in transformer: Hysteresis loss is due to reversal of magnetization in the transformer core.
Just like any other electrical machine, efficiency of a transformer can be defined as the output power divided by the input power. That is efficiency = output / input . Transformers are the most highly efficient electrical devices. Most of the transformers have full load efficiency between 95% to 98.5% .
In order to reduce the eddy current loss, the resistance of the core should be increased. In other words, low reluctance should be retained. In devices like transformers, the core is made up of laminations of iron. ie,the core is made up of thin sheets of steel, each lamination being insulated from others.
EMF equation of a transformer and Voltage Transformation Ratio. In a transformer, source of alternating current is applied to the primary winding. Due to this, the current in the primary winding (called as magnetizing current) produces alternating flux in the core of transformer.
An ideal transformer would have no losses, and would therefore be 100% efficient. In practice energy is dissipated due both to the resistance of the windings (known as copper loss), and to magnetic effects primarily attributable to the core (known as iron loss).
Eddy Current Loss. When an alternating magnetic field is applied to a magnetic material an emf is induced in the material itself according to Faraday's Law of Electromagnetic induction. These circulating currents are called Eddy Currents. They will occur when the conductor experiences a changing magnetic field.
Copper losses ( I²R)depends on Current which passing through transformer winding while Iron Losses or Core Losses or Insulation Losses depends on Voltage. So the Cu Losses depend on the rating current of the load so the load type will determine the powerfactor P.F ,Thats why the rating of Transformer in kVA,Not in kW.
Definition of core loss. : energy wasted by hysteresis and eddy currents in a magnetic core (as of an armature or transformer)
Just like any other electrical machine, efficiency of a transformer can be defined as the output power divided by the input power. That is efficiency = output / input . Transformers are the most highly efficient electrical devices. Most of the transformers have full load efficiency between 95% to 98.5%
Energy losses in an incandescent light bulb are very large; most of the input energy is lost in the form of heat energy. When energy is transformed from one form to another, or moved from one place to another, or from one system to another there is some energy loss.
Core losses majorly include Hysteresis loss and eddy current loss. Eddy Current loss can be reduced by increasing the number of laminations. The laminations provide small gaps between the plates. As it is easier for magnetic flux to flow through iron than air or oil, stray flux that can cause core losses is minimized.
The energy lost as heat, which is known as the hysteresis loss, in reversing the magnetization of the material is proportional to the area of the hysteresis loop. Therefore, cores of transformers are made of materials with narrow hysteresis loops so that little energy will be wasted in the form of heat.
In a transformer, the magnetic flux created by the primary coil induces a current in the core. This occurs in order to oppose the charge that produced the magnetic flux (Lenz's Law). The currents flowing in the core are called eddy currents. These currents produce heat, using up energy and so causing inefficiency.
It is the loss in a transformer that is excited at rated voltage and frequency, but without a load connected to the secondary. No-load losses include core loss, dielectric loss, and copper loss in the winding due to exciting current.
That's why compare to copper loss, iron loss is very very less and it can be ignored during short circuit test. Iron losses in short circuit test are not absent they are just neglected. Because in the short circuit test the LV winding is short circuited which means high currrent and low voltage in the secondary side.
P.T may be considered as a parallel transformer. The primary current of a P.T depends upon the secondary circuit conditions (burden). The primary winding P.T is connected across the line of voltage to be measured. With the help of P.T, a 120V voltmeter can be used to measure very high voltages like 11KV.
At no load, secondary current becomes zero due to open circuited at secondary. Therefore, only shunt branch component is left which is used to magnetise the transformer coils. The current flowing in coils leads to winding losses. No load current is the current which is used by the transformer to magnetize it's core.