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Understanding LV Circuit Breaker Fault Ratings

I think this post is going to be helpful to several of our readers. While the IEC low voltage circuit breaker Standard [IEC 60947-2, Low voltage switchgear...

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 ...

Welcome back Bottle

‘Kept looking at a card, y’see? Kept looking at it. Welcome back Bottle. Gods below welcome home. The Crippled God A Tale of the Malazan Book of the...

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...

Restricted Earth Fault Protection

The windings of many medium and small sized transformers are protected by restricted earth fault (REF) systems. The illustration shows the principal of...

What is an Open Delta Transformer

In three phase systems, the use of transformers with three windings (or legs) per side is common.  These three windings are often connected in delta or...

Cables for MV Power Distribution - Earthed versus Unearthed Systems

Power cables can basically be classified into earthed and unearthed cables, where earthed and unearthed refer to the application for which the cable is...

Post Editing Tips

If you at all familiar with programs like office and outlook, then adding and editing posts is pretty straightforward and intuitive.  However, there are...

Electromechanical Relays

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  While over recent years these have been replaced by microprocessor...

Material Properties

Everything physical in electrical engineering from insulations to conductors revolves around materials. Here we are listing common materials along with...

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