Current Transformer – Construction, Phasor and Errors

Current Transformer is an instrument transformer which steps down high value of current to a low value of current suitable for measurement devices. It is widely used in power system for measurement and protection purpose. We cannot think of power generation, transmission or distribution without...

In job interview often interviewer asks some numerical this is quit tricky and easy to answer without going into much calculation. In this post, I am going to discuss 3 most asked numerical questions in job interviews. These 3 questions are picked from my personal...

Geometrical Mean Radius (GMR) and Inductance

Geometrical Mean Radius GMR is basically the Geometric Mean of distances between the strands of a conductor. It is the fictitious radius of conductor having no internal flux linkage but only external flux linkage. To understand the concept of GMR and its calculation, it is...

Over Reach of Distance Relay

What is Meant by Over Reach? To understand the meaning of over reach, let us take an example of double circuit line in which one line is out of service and earthed at both end by Earth Switch. In the figure below, the distance relay...

Inductance of Single Conductor of Transmission Line

Inductance is the property of a conductor due to which it opposes a sudden change in current through it and a basic electrical parameter like resistance and capacitance. Inductance is defined as the total flux linkage per unit current. To analyse the electrical behavior of...

Calculation of Multiplication Factor of Energy Meters

Energy Meters are one of the important instrument to account for energy imported / exported in an industry. In Power Generating Stations, the cumulative reading of such energy meters are used for the calculation of total Million Units (MUs) of energy exported. On the basis...

Ring Main Unit (RMU) – Introduction

Ring Main Unit,RMU is a compact, enclosed and sealed type of Switchgear used for medium voltage power distribution. It is a complete Switchgear in itself. A complete Switchgear means, assembly of required switching devices, protection device as well as metering device. RMU of different voltage...

How to Disable Full DR Alarm in Numerical Relay?

These days mostly Numerical Relays are used for protection purpose instead of conventional Electromechanical Relays. In fact, Numerical Relays offer a variety of protection as well as trouble shooting features. A single Numerical Relay can provide many protection unlike conventional Electromechanical Relays. A single Numerical...