How many types of errors are present in the current transformers?

Current transformers (CTs) are used in electrical engineering to measure alternating current (AC) or to produce a reduced current used for protective relaying purposes and metering. These transformers can exhibit several types of errors, which can affect their accuracy and performance. The primary errors in current transformers include:

1. Ratio Error (or Current Ratio Error): This arises from the difference between the actual transformation ratio and the nominal (or rated) transformation ratio. The transformation ratio is ideally supposed to be constant, but in reality, it changes with the loading conditions, leading to inaccuracies.

2. Phase Error (or Phase Angle Error): This error refers to the difference in phase between the primary and secondary currents. Ideally, the phase difference should be zero (or 180 degrees, depending on the definition), but due to the inductive nature of the transformer, there is often a slight phase shift. Phase errors are particularly critical in power systems where phase relationships are important, such as in power factor correction and the operation of protective relays.

3. Saturation Error: This occurs when the magnetic core of the transformer gets saturated due to high current levels, significantly affecting the accuracy. Saturation of the core causes distortion in the secondary current waveform, making it a non-linear representation of the primary current, which can lead to considerable errors, especially in peak currents.

4. Burden Error: The effect of the load connected to the secondary winding (referred to as the ‘bur