Overcurrent Protection Course: Principles, Relays, Schematics and Settings


Learn how overcurrent protection works in power systems, the concept of short circuits, different types of faults, and settings. Special attention is paid to instantaneous and time delay protection types (normal, very and extremely inverse relays). 21 lessons in 3 hours and 29 minutes.


Overcurrent protection is by far the simplest type of protection widely used in electrical power systems. It’s estimated that more than 80% of relays in industrial and power systems are overcurrent type. Therefore it is essential to fully understand and learn the real art of overcurrent relays. The course consists of 21 lessons in 3 hours and 29 minutes.

The course starts with explaining what is short circuit and the different types of faults in power systems and continues with the concept of short circuit current, load current, and percentage impedance of generator/transformer.

The course will teach you what are primary and secondary values needed for various protection calculations (fault MVA and fault current, plug settings, pick current, etc.). The course covers current transformer (CT) basics and you will learn to calculate CTs, how CT primary and secondary current ratings are selected, CT polarity and saturation, metering and protection cores, etc.

Special attention is paid to explaining the types of overcurrent protection i.e., instantaneous and time delay. Inverse time overcurrent relay, its types (Normal Inverse, Very Inverse & Extremely Inverse relays) and settings are explained in detail.

Additional information


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