Each CT has a polarity mark—usually denoted as P1 and P2 on the primary, and S1 and S2 on the secondary. A clear understanding of polarity is useful in understanding and analyzing transformer connections and operations as well as testing protection relays and systems. As we continue to witness the rapid evolution of technology, one specific development that has been gaining. What is Differential Overcurrent Protection? In any closed circuit, the current exiting and entering the power supply must be equal. If this marking is. CT polarity. Reversed CTs flip the measured angle. I document the exact values at commissioning and after each maintenance window.
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