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senthilazhagan • Jan 21, 2009

What is burden in Current Transformer?

Any body can tell what is burden in current transformer?

manoj_2all • Mar 31, 2010
The burden of a current transformer is indicated in its nameplate. The burden is rated in VA. such as 15 VA or 25 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 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.
Satyadeo Vyas
Satyadeo Vyas • Jul 18, 2019

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. 

How to Calculate Burden of CT

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