Many power generation and distribution systems employ current transformers to monitor the flow of current through electrical devices. To ensure proper installation and operation, current transformers are often subjected to one or more tests performed in accordance with well-defined standards, e.g., IEEE C57.13.1, IEC 60044-1, and IEC 60044-6. Examples of these tests include ratio tests, excitation tests, burden tests, polarity tests, winding resistance tests, phase angle tests, etc. To calculate the ratio, excitation curve, and knee point of a current transformer using some traditional test methods, the primary conductor of the transformer must first be disconnected. With the primary circuit open, a test signal can be applied to the secondary winding and the resulting current/voltage in the primary winding may be measured. These results may then be used to determine characteristics used to evaluate the current transformer such as ratio, saturation curve, and knee point.
If the transformer is a multi-ratio current transformer having multiple taps, test leads may be changed (e.g., manually or with a relay switching matrix) and a similar test may be performed similar to that described above. This testing process is typically repeated for each combination of taps. Thus, multiple tests are typically performed to determine the ratios, saturation curves, and knee points for a multi-ratio current transformer. As such, conventional methods for testing current transformers can be relatively labor intensive and time-consuming.