The burden on the current transformer is imposed by the connected device and the impedance of the connecting wires which connect it. Current Transformer Application Considerations. IEEE C57.13-2016, Table 19: Standard VT burdens at 60 Hz Burden designation Secondary volt-amperes Burden power factor W 12.5 0.10 X 25.0 0.70 M 35.0 0.20 Y 75.0 0.85 Z 200.0 0.85 ZZ 400.0 0.85 Calculating the burden of a Current Transformer. Burden of Instrument Transformer (CT PT and CVT) September 11, 2019 July 29, 2019 Instrument transformers are basically the transformers like normal purpose transformers, instrument transformers have also to carry electrical loads. The burden of a current transformer is indicated in its nameplate.
+For current transformers, the 100% rated current limit also applies to the current corresponding to the continuous thermal current rating factor.

Burden: External load applied to the secondary of the CT is called ‘burden’.

Back to the Basics – Current Transformer (CT) Testing As test equipment becomes more sophisticated with better features and accuracy, we risk turning our field personnel into test set operators instead of skilled field service ... burden and fault current. All instruments that use a current transformer to measure line current must terminate the CT with a resistance (impedance in same case which means there is some inductance involved).

Typical burden ratings for IEC CTs It transforms the high voltage current into the low voltage current due to which the heavy current flows through the transmission lines is safely monitored by the ammeter. While specifying metering or auxiliary current transformers, the design burden needs to be closely matched to the actual connected burden.
Here are some very important current transformer interview questions with proper answers which are mostly asked with Electrical Graduates in every industrial interview as well as university exam viva.

A CT supplier should be given the burden when ordering.

These … A burden resistor connected across the secondary produces an output voltage proportional to the resistor value, based on the amount of current flowing through it.

The total burden is a combination of impedance offered by watt-hour meter coils, relay current coils, contact resistance, terminal blocks, wire resistance and test switches used in … The burden, in a CT is the (largely resistive) impedance presented to its secondary winding.

CT primary current rating should be equal to or greater than the maximum expected current for the associated breakers or transformers. The burden of a current transformer can be defined as the total impedance in ohms on the secondary output terminals.