Transformers, Electrical Engineering

AC Operation of an iron core

1428_Transformers.png

 

 

 

563_Transformers 1.png

 

Hence, if a wattmeter were used to measure the power delivered over a full period of the waveform (which will also be the average power delivered over a long period of time), the answer should be zero.  In practice, there will be a finite energy loss recorded, which is found to be much larger when the coil is wound on a conductive former than when it is air cored.

The energy loss is attributed to:
 
 
1) 'Copper losses', i.e. loss due to current flowing through the resistance of the windings, (P=iR).This power loss occurs whether the
core is air cored or not.

2) 'iron losses'. These arise due to two causes:
 
a)  the hysteresis loss due to the energy dissipated in continually reversing the magnetisation of the core. The energy taken per cycle is the area of the hysteresis B/H curve.

b) Eddy current losses due to  induced currents circulating within the conductive core of the coil. These are induced by the changing current in the coil and circulate in such a way as to try to oppose the change in the coil current. They are minimised by laminating the core to increase the path resistance for the circulating current and hence reduce its value. Since Power = i.R, reducing the current reduces the power even though the resistance is increased.

A transformer is produced by winding a second coil onto the former.

1393_transformer is produced by winding a second coil.png

 

Note the polarity of the currents. The current in the primary coil creates a flux in the core with a direction according to Maxwell's RH corkscrew rule. The current induced into the secondary coil is in such a direction as to try to oppose the original flux change in the core.

 

 

Posted Date: 8/23/2012 3:16:26 AM | Location : United States







Related Discussions:- Transformers, Assignment Help, Ask Question on Transformers, Get Answer, Expert's Help, Transformers Discussions

Write discussion on Transformers
Your posts are moderated
Related Questions

Q. Can you explain Twos complement addition? 2's Complement Addition Two's complement addition follows the same rules as binary addition. For example, 5 + (-3)  =  2

LC Filter To the load resistance R L the ripple factor is directly proportional in the inductor filter and inversely proportional to R L in the capacitor filter. Hence i

Switching characteristics during turn on A positive  gate  pulse  between  gate and  cathodeis sufficient to turn  on a thyrisotr. In  this period  thyristor  changes its stat

Voltage Doubler: The network of Fig. is a half wave voltage doublers. During the positive voltage half cycle across the transformer, secondary diode D 1 conducts, charging ca

Q. Explain working of Digital-to-Analog Converters? Digital-to-Analog (D/A) Converters For the results of digital computations to be used in the analog world, it becomes n

For the circuit of Figure(a), obtain the complete solution for the current i L (t) through the 5-H inductor and the voltage v x (t) across the 6- resistor.

Ginny Jones currently works as the VP-Product Strategy for a well-established enterprise software company. She and her friend, Tom Robinson, currently CFO at a competing firm (and

The following four output displays of an oscilloscope (right hand side, below) show waveforms of a biased diode ac circuit. An example is illustrated on the left hand side. VIN is

Explain the energy bands in solids. There are as several energy bands in a solid as there are energy levels in the parent atoms. Many electrical properties of significance