Variable Frequency Drive
Variable frequency drives are widely used to control the speed of ac motors. This note looks at the mechanisms which enable drive units to control the...
Differential protection, the good old days
This morning I was explaining how differential protection works to a junior engineer. To give him something to read I opened up the NPAG (Network Protection...
Introduction to Lighting
When looking at the design of a lighting scheme it is useful to have an understanding on the nature of light itself and some of the basic theory associated...
Switchboard - Forms of Internal Separation
IEC 61439 'Low-voltage switchgear and controlgear assemblies', specifies standard arrangements of switchboard (call forms of internal separation). The...
UPS - Uninterruptible Power Supply
A UPS is an uninterruptible power supply. It is a device which maintains a continuous supply of electrical power, even in the event of failure of the...
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...
Earth Electrode Resistance
Earthing of electrical systems is essential for the correct functioning and the protecting of life and equipment in the event of faults. The earth electrode...
Inductance
When current flows within a wire, a magnetic field is created. The potion of this magnetic field perpendicular to the wire is called the magnetic flux...
Lead us, Warleader
Delum, who had watched all in silence, his face empty of expression, now spoke in turn. ' "Lead us, Warleader, into glory."'
Reading is something I do...
Sony Pocket eBook Reader
For the past few years I have reading eBooks on my HTC touch phone. On and off I have debated buying an eReader and recently purchased a Sony PRS-300 ...