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...

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...

When selecting a cable, the performance of the cable under fault conditions is an important consideration. It is important that calculations be carried...

Our IEE cable sizing was wrote a few years ago and had become rough around the edges. I thought it was time to give the tool a service. Unfortunately when...

Visitors who like to type web address rather then click menus may be interested in how our URL structure works.

In 2011, with the introduction of it’s Panda search ranking algorithms, Google introduced tools for determining the original author of posts.  The intention...

I was having a conversation the other day about voltage levels.  While everyone was in agreement that low voltage was 1000 V and less, there was more confusion...

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 ...

Depending where in the world you work, you are likely following one of two standards International Electrotechnical Commission (IEC) National...

A battery consists of one or more cells, each of which use stored chemical energy to produce electrical energy, There are many types of cells and these...