Numerical Relay Working Pdf

Numerical relays working explained in this post with the help of a numerical relay used in industrial applications.

Numerical relay working pdf.

In utility and industrial electric power transmission and distribution systems a numerical relay is a computer based system with software based protection algorithms for the detection of electrical faults. A single numerical relay can monitor multiple parameters like current voltage frequency onset time offset time etc. Numerical relay is the relay in which the measured ac quantities are sequentially sampled and converted into numerical data that is mathematically and or logically processed to make trip decisions. The first numerical relays were released in 1985.

Lecture 18 directional overcurrent relaying. A typical numerical relay can store as much as 520 events and 50 disturbances. Lecture 19 directional overcurrent relay coordination tutorial lecture 20 directional overcurrent relay coordination in multi loo. Event and disturbance recording is a must feature for a digital relay because these data are used for troubleshooting any event.

Brief introduction about relay. There are two types of phase comparators. Module 5 directional overcurrent protection. Numerical relay is actually the digital relay as.

Such relays are also termed as microprocessor type protective relays. Numerical relay working and hardware architecture. A relay is a protection device that senses the fault in the circuit and gives a trip signal to the circuit breaker to isolate the faulty circuit. Academia edu is a platform for academics to share research papers.

In short a phase comparator compares two input quantities in phase angle vertically irrespective of the magnitude and operates if the phase angle between them is 90o. A numerical relay has the functionality that previously required several discrete relays therefore the relay functions such as overcurrent or earth fault are referred to as relay elements. Lecture 16 psm setting and phase relay coordination tutorial lecture 17 earth fault protection using overcurrent relays. θ is the angle by which s 2 lands s 1 if β 1 β 2 90 o the comparator is called cosine comparator and if β 1 0 and β 2 180 o it is a sine comparator.

Numerical relays are based on the use of microprocessors. Rom is used to store software needed for the working of relay. Electromechanical and static relays have fixed wiring and the setting is manual. A big difference between conventional electromechanical and static relays is how the relays are wired.

Each relay element is in software so with modular hardware the main signal processor can run a vast variety of relay elements.