Numerical relay is actually the digital relay as.
Numerical relay working pdf.
Lecture 19 directional overcurrent relay coordination tutorial lecture 20 directional overcurrent relay coordination in multi loo.
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.
A big difference between conventional electromechanical and static relays is how the relays are wired.
Rom is used to store software needed for the working of relay.
Lecture 18 directional overcurrent relaying.
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.
They are functional replacements for electro mechanical protective relays and may include many protection functions in.
Numerical relay working and hardware architecture.
Electromechanical and static relays have fixed wiring and the setting is manual.
Such relays are also termed as microprocessor type protective relays.
Lecture 16 psm setting and phase relay coordination tutorial lecture 17 earth fault protection using overcurrent relays.
A typical numerical relay can store as much as 520 events and 50 disturbances.
Brief introduction about relay.
A single numerical relay can monitor multiple parameters like current voltage frequency onset time offset time etc.
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.
Each relay element is in software so with modular hardware the main signal processor can run a vast variety of relay elements.
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.
Rom is also needed for storing event and disturbance data.
Event and disturbance recording is a must feature for a digital relay because these data are used for troubleshooting any event.
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.
Numerical relays are based on the use of microprocessors.
There are two types of phase comparators.
And the same relay can be used for analysing and monitoring multiple faults such as over current over fluxing different current and more.
Module 5 directional overcurrent protection.
