Protection of Three Phase Power Transformer

Abstract: Transformers must be protected in order to limit the damages due to abnormal currents and over voltages. The role of protection is to ensure that these withstand limits can never be exceeded, therefore clearing the faults as soon as possible. Different transformers demand different schemes of transformer protection depending upon their importance, winding connections, earthing methods and mode of operation. The protection of transformer is important as it involves human risk as well as economic risk. There are different types of protection provided to a power transformer such as a Differential protection and Restricted Earth fault protection which together are known as Primary Protection Schemes; Backup Protection is also employed namely three phase overcurrent and earth fault. There are different types of protection equipment‟s available on a transformer like Buchholz relay, winding temperature indicator, oil temperature indicator, oil surge relay and pressure release valve etc. To avoid any danger to human life as well as to save transformer from any kind of damage, protection to a transformer should be provided. Index terms: Buchholz, Differential, Restricted Earth fault, Oil Surge Relay, Pressure Release Valve.

Keywords: Differential Protection, Restricted Earth Fault Protection, Three Phase Overcurrent and Earth Fault, Buchholz Relay, Winding Temperature Indicator, Oil Surge Relay, Pressure Release Valve