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## What are the errors that occurs in instrument transformers?

There are two sources of error in instrument transformers, namely **ratio error and phase angle error**.

## What are the sources of errors in AC bridge measurement?

Errors due to **stray magnetic fields Leakage errors Eddy current errors Residual errors Frequency and waveform errors**.

## What are errors in CT?

The use of a C.T. leads to the introduction of two errors in power measurement. Explanation: Ratio error of a C.T. is defined as **the ratio of the magnitude of the difference between the nominal and actual ratio with respect to the actual ratio**.

## Which of the following is most important way to reduce errors in potential transformer?

Explanation: In a potential transformer, the winding resistance is usually minimised by using thick conductors and by making use of small length for the turns. Explanation: By **maintaining the primary and secondary windings together in a P.T.** and also by reducing the leakage flux, we can minimise the leakage reactance.

## What are the steps to be taken for minimizing errors in potential transformer?

In order to reduce these errors such that the accuracy is improved by designing the transformers in such a way that they windings have appropriate magnitudes of internal resistance and reactances. In addition to this, the core should **require minimum magnetizing and core loss components of exciting current**.

## What is composite error in current transformer?

Accuracy of a current transformer is measured by the composite error. This is defined as **the difference between the ideal secondary RMS current and that of the actual secondary current**. … The ratio of the accuracy limit current to the rated current is the ‘accuracy limit factor’.

## Which option is the most suitable for reducing errors in a current transformer?

The errors in current transformer can be reduced by designing them with : **High permeability and low loss core materials**, avoiding any joints in the core and also keeping the flux density to a low value. Using primary and secondary windings as close to each other as possible.

## Why large error is introduced in the measurements done by the instrument transformers?

With more instruments in the circuit, **a higher voltage is required to make the current flow** and this, in turn, requires more flux to flow through the core and hence a greater magnetizing component of the primary current. This will result in an increase in the ratio and phase angle error of the current transformer.