Abstract :

In a fire at the Tasikmalaya EHV main substation on January 28, 2009, a phase-R, 166 MVA, 500kV/150 kV inter bus Power Transformer was destroyed, knocking off power to the JAMALI (JAVA-MADURA-BALI) interconnection system. The root of the issue has not been identified. Even after switching out the IBT's power transformer, the neutral earthing current continues to exhibit strange behaviour. Despite the little load, it was found that the neutral earthing current was much higher than in any other IBT transformer. We'll be collecting measurements, running simulations, and analysing data to find out what's up with the Ynyd-configured IBT 500/150 kV power transformer's abnormal neutral earthing current. To compare with other common situations, neutral earthing current was measured at three locations, including the Tasikmalaya EHV main substation, using true rms current recording for one week. Using a true rms current meter, we will determine whether or not a delta tertiary winding on an IBT t