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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 ...

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 ...

Star-Delta Motor Starting - Performance

Many questions sent in to the site are in connection with motor starting and in particular star-delta.  For all but the simplest application, there is...

Meeting room of the future

The IET site has a video of a visit showing of a high tech meeting room developed at Napier University in Edinburgh. It a good demonstration of innovative...

Useful Motor Technical Information

Sometimes it’s useful to be able to quickly lookup a piece of technical information.  This note is a collection of information related to motors, and in...

Aluminium Windings - Dry Type Transformers

The other day I was talking to a colleague who is a building services consultant.  Despite regularly specifying dry-type/cast resin transformers he was...

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...

Random Numbers

Using laser optical pulses the random number generator utilizes the time between arrival of random photos to generate the numbers, ensuring true accuracy...

Electromechanical Relays

Electromechanical relays have been the traditional backbone of electrical protection systems.  While over recent years these have been replaced by microprocessor...

Generation of a Sine Wave

A fundamental concept behind the operation of alternating current systems is that voltage and current waveforms will be sinusoidal – a Sine Wave. This...

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