Construction & Working of Current Transformer

Construction & Working of Current Transformer Points : Construction & Working of Current Transformer Current transformer takes the place of shunt in d.c. measurement and enabler heavy alternating current to be measured with the help of a standard 5A range a.c. ammeter. Shows the current or series transformer. It has a primary winding of one or more turns of thick wire connected in series with the line carrying the current to be measured. The secondary consists of a large number of turns of fine wire and feeds a standard 5A ammeter or the current coil of a watt- meter or watt- hour-meter as shown. For example, a 1000/5A current transformer with single-turn primary will have 200 secondary turns, obviously, it steps down the current in the 200:1 ratio whereas it steps up the voltage drop across the single-turn primary (an extremely small quantity) in the ratio 1:200. Hence, if we know the current ratio of the transformer and the reading of the a.c. ammeter, the line current can be calculated.