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
loses and efficency of generator

Derive Lame's equation for a thick cylinder subjected to internal pressure with clean diagrams. Evaluate the maximum and minimum hoop stresses across the section of a pipe of400


CRM Triangle The following diagram which is called as CRM Triangle. Strategy refers to the whole stand taken through the company. It could selected a defensive posture in t

Current  Source Inverter (CSI) Current  source  inverter has constant  input  but it  can be  adjusted. In CSI  the amplitude of output  current is  independent of load. The lo



project to write a program to simulate a dc motor on a matlab

Q.   Enumerate different types of errors in  measurement. How can these errors be minimized.                Sol. Types of errors: Errors may arise from different sources and

Q. Two shunt generators operate in parallel to supply a total load current of 3000 A. Each machine has an armature resistance of 0.05and a field resistance of 100. If the generat