Ring type ( or rectangular type ) CT are normally preferred over other types of CT. because they are simple in construction, mechanically stronger and cheaper. In a ring type bar primary type CT the working ampere-turns are determined by the primary current and therefore necessarily, the accuracy that can be offered with these CT becomes progressively inferior as the rated primary current decreases.'-If higher accuracy and burdens are required for CT of low primary current wound types CT are used.

It is not possible to use line current directly for measurement and relaying purpose due to its high value and insulation problem. CURRENT TRANSFORMER which is widely known as 'CT' is a piece of electrical equipment which converts line current ( primary current ) in to small standard current values which are suitable for the devices to which it is connected e.g. measuring instruments, meters, protection relays.

Ring type ( or rectangular type ) CT are normally preferred over other types of CT. because they are simple in construction, mechanically stronger and cheaper. In a ring type bar primary type CT the working ampere-turns are determined by the primary current and therefore necessarily, the accuracy that can be offered with these CT becomes progressively inferior as the rated primary current decreases.'-If higher accuracy and burdens are required for CT of low primary current wound types CT are used.

It is not possible to use line current directly for measurement and relaying purpose due to its high value and insulation problem. CURRENT TRANSFORMER which is widely known as 'CT' is a piece of electrical equipment which converts line current ( primary current ) in to small standard current values which are suitable for the devices to which it is connected e.g. measuring instruments, meters, protection relays.