-Primary winding connects in series with line carrying the current to be measured.
-Primary consists of very few turns causing no appreciable voltage across it.
-Secondary winding has larger number of turns.
-Ammeter is connected directly across the secondary terminals.
-Thus, a current transformer operates its secondary nearly under “short circuit” condition.
-One of the terminals of secondary winding is earthed to protect equipment and personnel in the vicinity in the event of an insulation breakdown.