The burden is the termination impedance of the measuring instrument. The total burden of an instrument transformer may be due to connected voltmeter, watt meters, power factor meters, frequency meters, energy meters and other type of relays and wiring systems. The rated burden of this Instrument Transformer is the volt- ampere loading which is permissible without errors exceeding the limits. Burden of Instrument Transformer Burden is the VA rating of the transformers. Basically, there are two Classes of an Instrument Transformer, one is Protection Class and another one is Metering Class. The measuring instrument can be an analog or digital energy meter, a data logger or a recorder. Burden across the secondary of an instrument transformer is also defined as the ratio of secondary voltage to secondary current. The metering system consists of ammeters, voltmeters, watt meters, power factor maters, energy meters etc. More clearly it is the volt ampere rating at rated secondary voltage. Instrument Burden. This is the maximum allowable load at the secondary, below which the transformers causes limited errors. 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). The units of burden are ohms.

The Burden of an Instrument Transformer is the rated Volt-Ampere loading which is permissible without errors exceeding the limits for a particular class of Instrument Transformer. “Impendence of secondary circuit expressed in ohms , Power factor angle is called burden.” “Rated burden” of instrument transformer is refer to maximum load in volt-amp (VA) which may be applied across the secondary terminals without changing the ratio & phase angle errors exceeding the permissible limits. ZL = secondary voltage/ secondary current = V / I.