A current transformer is kind of electrical instrument, which is produced especially to provide a flow of current in the secondary circuit that is correctly perpendicular to the amount of current flowing in its primary circuit. To calculate current and monitor the operation of power grid Current Transformers are used widely and it is classically defined by its current ratio from primary to secondary.

Current transformers are most widely used in metering and protective relaying in the electrical power industry where they make easy the safest obligation of a huge amount of currents, regularly in the presence of high voltages on the circuit. The current transformer securely cut offs to measure and to manage a circuitry from the high voltage essentially available on the circuit. Current transformers are normally controlled by passing a single primary turn under a well-insulated toroidal core with enormous turns of wire wrapped. Current transformer is further used to measure the flow of current and as well in monitoring the operation of the power used. The CT is fundamentally defined by its value of current ration flowing from primary to secondary.

There are some factors that improve the current transformer's accuracy. They are like burden, rating factor, physical CT configuration etc.

The value of impedance is the outcome for the burden in a Current transformer circuit. The basic items that are reasons for burden in current calculation circuit are intermediate conductors and switch blocks meters and the sources are the conductors among the meter and the CT. Further the problem of producing high resistance occurs due to placing a substation meter at some level of distance from meter that could beat by using current transformer with 1 amp that produce low voltage drop.

The Rating Factor of current transformers that are dependent on ambient temperature, is a factor used to determine the correct maximum measurable primary current by multiplying the full load of a CT. In order to maintain the accuracy level in rising of ambient temperature, the CT would have low capacity, and the rating factors of the CT's would range from 35 degrees Celsius and 55 degrees Celsius.

Another important factor for accuracy of current transformer is Physical Current Transformer Configuration. If in case the conductors are not really centered in circular or oval, the inaccuracy occurs in CT and this needs to be notified for correct accuracy. Normally, the CT's are constructed in many ways like passing a single primary turn by way of well-insulated toroidal core wrapped with many turns of wire. To calculate the waveforms of high frequency or pulsed currents within high pulsed power systems wideband current transformers are specially used.