RLC series is very significant, when it comes to deciding which current transformer, to be installed. The prime parameters is the burden of the load connected, higher the rated burden of the current transformer, higher level of load it can manage.
Calculating the Burden of a Current Transformer.
The burden is rated in VA. The rated VA indicates the load the transformer can take.
The current transformer is connected to a measuring instrument or a protective relay by means of wires. The burden on the current transformer is imposed by the connected device and the impedance of the connecting wires which connect it. The VA load of the device can be obtained from the data sheet provided by the manufacturer. The total burden is the sum of the burden of the connected devices and the resistance of the wires. The inductive component of the wire impedance is usually neglected as it is minimal.
The burden of a current transformer can increase over time as the resistance of the connecting wires may slightly increase due to age, change in temperature and loosening of connections. Hence, the current transformer should never be loaded to 100% of its capacity.