Protection Engineering Basics and Schemes Protection Engineering | Page 9
1.1.1 Operation :
Current transformer is acted same like step up transformer , in which voltage is increased by the mention turn ratio .
V = 4.44fBAN Where f is frequency , B is magnetic field density , A is area of cross section , N is turn ratio .
1 st we need to analyze below mention simple drawing or layout of Current transformer
What happened when current flows in primary , the flux due to that flow of current cut the secondary number of turns and induce voltage in secondary , due to that induce secondary voltage the current flow in secondary windings , but remember transformers are magnetically coupled so core of transformers must need to be magnetized before any current flow , the current required to magnetized the core of transformer is excitation current , now see this equation