Expanding of test current of CT by equivalent magneto motive force method up to 20 kA

The design and electrical specifications of the window type CT (W-CT) test system based on Equivalent Magneto Motive Force (EMMF) method, and sample data for CT under test is presented. This new high current system will be the JEMIC standard for expanding test current from 5 to 20 kA and for testing CT. It has also been designed so that the test results of window type CT changes with ease can be experimentally evaluated by the EMMF Method. The residual flux density of 0.36 T in the toroidal core was detected depending on the primary winding location as one fourth of saturation magnetic flux density of CT. Applied voltage, input current and power factor at the frequency of 55 Hz were 170 V, 25A, 0.5 respectively for testing a CT at 20 kA.