The 110 and 220 kV lines of the main grid are protected by means of two primary protection schemes (two distance relays or a distance and a differential line relay) or a primary protection relay (distance relay) and a backup protection relay (overcurrent and. The 110 and 220 kV lines of the main grid are protected by means of two primary protection schemes (two distance relays or a distance and a differential line relay) or a primary protection relay (distance relay) and a backup protection relay (overcurrent and. Automatic system protection is used to limit the impact of faults by means of measures beyond disconnecting the defective component. System protection can be used to increase system security, transmission capacity, or a combination of these. Automatic system protection uses two different principles. Fingrid's application guideline for relay protection presents the operating principles of the relay protection in Fingrid's 110, 220 and 400 kV power networks and the requirements for operation of the protection systems of Fingrid customers (hereinafter referred to as 'customer'). The application. Numerical relays are based on the use of microprocessors. Numeric. Generally, there are several different types of numerical protection relays. Each type, however, shares a similar architecture, thus enabling designers to build an entire system solution that is based on a relatively small number of flexible components. They work on the following two main operating principles:- (1) Electromagnetic attraction (2) Electromagnetic induction 1. Electromagnetic Attraction Relays Electromagnetic attraction relays operate by. This article covers various types of protective relays, such as overcurrent, directional, and differential relays, highlighting their operating characteristics and applications in electrical systems.
