DECREASING THE EFFECT OF THE SECOND HARMONIC COMPONENT FOR POWER TRANSFORMER PROTECTION

The transformer is one of the most expensive and important electrical equipment of a power distribution system and therefore the loss of such equipment through catastrophic failure can be very costly. Furthermore, repair or replacement is expensive and time consuming. To avoid this, methods and systems for monitoring and protecting of power transformers in service have been developed in recent years. To avoid the needless trip by magnetizing inrush current, the second harmonic component is commonly used for blocking differential relay in power transformers. This paper describes a new approach for power transformer differential protection that ensures security for inrush phenomenon during switching on. For this purpose, a new AC drive circuit is designed and implemented in a laboratory environment. Finally, we compare the behavior of this new drive for real cases of magnetizing inrush conditions