Use of standard CT and PT while testing a given CT and PT

[Pritam]

Why do we use standard Current Transformers and Standard Potential Transformers while testing a given CT and PT? For what purpose these standard CTs and PTs are used in testing field?

[ktelectrician]

A voltage transformer concept or potential transformer concept is the same as a theory of basic step down transformer. Between the phase and the ground primary of the voltage transformer is connected. voltage transformer has lower primary turns than its secondary windings, for the purpose of stepping down. The voltage of the system is applied over the terminals of the primary winding of that transformer, after which secondary voltage appears in proper proportion over the secondary terminals of the potential transformer.

[wrh9278]

Why do we use standard Current Transformers and Standard Potential Transformers while testing a given CT and PT? For what purpose these standard CTs and PTs are used in testing field?

Not sure I understand the question. If you are talking about the transformers inside test equipment, like a TTR for example, the known ratio is used to calculate the measured ratio.