Current Transformer Effect of secondary open circuit

Current Transformer Effect of secondary open circuit Points : Current Transformer Effect of secondary open circuit It is worth noting that ammeter resistance being extremely low, a current transformer operates with its secondary under nearly short-circuits conditions. Would it be necessary to remove the ammeter or the current coils of the wait meter or a relay, the secondary winding must, first of all, he short circuited before the instrument is disconnected. If it is not done, then due to absence of counter ampere-turn of the secondary, the unopposed primary emf will set up an abnormally high flux in the core which will produce excessive core less with subsequent heating of core and damage to the transformer insulation and a high voltage across the secondary terminals. This is not the case with the ordinary constant-potential transformers because their primary current is determined by the load on their secondary whereas in a “C.T.”, the primary current determined entirely by the load on the system and not by the load on its own secondary. Hence, the secondary of a “C.T.” should never be left open under any circumstances.