Electromechanical Relays

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  While over recent years these have been replaced by microprocessor...

8 Steps to Low Voltage Power Cable Selection and Sizing

A recurring theme on our forums is cable sizing. Now many installations are unique and require special consideration. However, a lot of the time things...

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...

Power Transformers - An Introduction

One of the fundamental requirements of an alternating current distribution systems it to have the ability to change the magnitude of voltages.  It is more...

Electrical Engineering

Electrical engineering is a field that covers a wide variety of sub-fields, including electricity and electronics. It is a field that goes back to 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...

Frame Leakage Protection

While not as popular as it once was, frame leakage protection does still have some use in some circumstances.  In essence frame leakage is an earth fault...

RLC Circuit, Resistor Power Loss - some Modelica experiments

Modelica is an open source (free) software language for modelling complex systems. Having never used it before, I thought I would download a development...

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...

Magicians of Engineering

The other day I was reading 'Night of the New Magicians' by Mary Pope Osborn with my son.  The story is about a young boy and girl who travel back in time...

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