What is burden in Current Transformer?
Any body can tell what is burden in current transformer?
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 datasheet 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.
The CT burden is very important parameter for protection. The higher burden lead to saturation of CT.
The CT is connected to the protection relay. The CT winding has resistance. The lead wire connecting relay and CT has resistance and relay also has certain resistance. If we sum up all three resistances we get the burden of CT.
This tutorial on CT burden may be helpful.