Current transformer reduces the primary current to a certain extent in normal operating conditions. It is a measurement transformer which the phase difference between the primary and secondary current is zero. It provides the insulation of relays and measurement devices in high voltage system. Its windings which are connected series to circuit are called primary, its windings which feeds the relay and measurement devices are called secondary. Dividing the primary circuit current to the secondary circuit current indicates the conversion rate of the current transformer. Current transformers are wound on steel core. Energy line between the coil and core should be good insulated. Secondary tips should be by-pass when measurement is not done. If not, dangerous results can occur due to the high voltage.
Current transformers used in low voltage circuits are used as making with busbar or winding. Winding current transformers are usually manufactured as portable type or stepping. Getting bigger the current value through the primary, its winding is a line busbar through the middle of the transformer core. These type of transformers are called busbar type current transformers. In general, they are used in constant places as dry and oily
