CT Polarity and HT Panel Charging

I would suggest you to test the polarity and mark it appropriately. Even if it doesn't affect you now; it will help to do the future maintenance job or modification work. You can do the test with a simple method (see the thread http://cr4.globalspec.com/thread/33197 ).

The incorrect polarity will affect the Watt meter, Energy meter, pf meter, Differential protection, Reverse power protection etc. (if the CT is used for these purpose).

-MS

Guest,

Even though it is possible to reverse the secondary CT connections to the correct polarity after energizing the panel, you must respect the high element of danger involved, especially at 22kV.

Since extremely high voltages are developed if an energized CT secondary circuit opens, and some very bad accidents have occurred, in the interest of safety I would highly recommend verifying all details, including the polarity before energizing 22 kV.

Regards, CJM

Since ct is used for protection purpose also, it is required to test polarity when used for Restricted E/F protection,differential protection. Otherwise for faults within and beyond the protection region, the sum values ( when multiple cts are used) will be erratic& may cause false tripping or even worse, will not trip at all

regards

E ANANDAN