DC Component of Asymmetrical Faults
    The image (reproduced from IEC 60909) shows a typical fault in an ac system.  From the illustration it can seen that there is an initial dc component ...
 
    How a Digital Substation Works
    Traditionally substations have used circuit breakers, current transformers (CT), voltage transformers (VT) and protection relays all wired together using...
 
    DC Motor Operation
    Coils of wire on the rotor carry a d.c. current which generates a magnetic field. A stator magnetic field is created using either permanent magnets or...
 
    Fault Calculation - Per Unit System
    Per unit fault calculations is a method whereby system impedances and quantities are normalised across different voltage levels to a common base.  By removing...
 
    Resistors
    Resistors are electronic components that oppose the flow of current.  Manufactured in various types and ranges they have a wide application to electronics...
 
    Introduction to Traction Substations
    Following on from my post on railway electrification voltages, I thought an introduction to traction substations would be a good idea. Traction substations...
 
    Switchboard - Forms of Internal Separation
    IEC 61439 'Low-voltage switchgear and controlgear assemblies', specifies standard arrangements of switchboard (call forms of internal separation).   The...
 
    Why a Sine Wave?
    I received this question by email a few weeks. First thoughts was that it is a product of the mathematics of rotating a straight conductor in a magnetic...
 
    Paths of Flight
    GE have put together a time-lapse video shown flight take-off and landings at some airports. An interesting view:
 
    Nikola Tesla 
    Nikola Tesla was born exactly at midnight on July 10, 1856 in the tiny village of Smiljan, Lika in Croatia. In his late teens, Tesla left the village to...