CT terminals

[rbyrne15]

Hi all, could anyone tell me what the test terminals on a window-type Current Transformer are intended for: what type of "tests" might we use them for?


Richard Byrne, E.E.T.

 

[Zogzog]

Turns ratio (TTR)

 

[raisinbran]

rbyrne15,
These terminals are used for a modified primary injection test. An example would be 100:5:5 ratio - (primary:secondary:test). A small test current is injected into the 5 ampere test winding. A replica current is generated in the 5 ampere CT secondary winding which is then fed to the protective relays. You can now test the circuitry without the high currents/high voltages associated with primary injection testing.
Raisinbran