CT & PT Testing
Video - CT/PT Analyzer
Theory - CT/PT Testing
CT (Current Transformer) – Theory
Like any other transformer, a current transformer has a primary winding, a magnetic core, and a secondary winding. The alternating current flowing in the primary produces an alternating magnetic field in the core, which then induces an alternating current in the secondary winding circuit. An essential objective of current transformer design is to ensure that the primary and secondary circuits are efficiently coupled, so that the secondary current bears an accurate relationship to the primary current.
PT (Potential Transformer) – Theory
A Voltage Transformer theory or Potential Transformer theory is just like theory of general purpose step down transformer. Primary of this transformer is connected across the phases or and ground depending upon the requirement. Just like the transformer, used for stepping down purpose, potential transformer i.e. PT has lower turns winding at its secondary. The system voltage is applied across the terminals of primary winding of that transformer, and then proportionate secondary voltage appears across the secondary terminals of the PT.
Below is the list of Major tests conducted on CT & PT
Insulation Resistance Test
Secondary/Loop Resistance Test
Burden Test (optional test)
Magnetization Curve Test (optional test)
Hysteresis Curve Test
Turns Ratio Test (optional test)
Primary Injection Test
High Voltage Test