Fundamental electrical engineering concepts and theory
If you want to check a circuit is dead (not live), you should always use the three point method. First check a known live circuit, then check the dead...
The inventor of the first visible light-emitting diode makes history again this year as it begins to show customers a 40-watt replacement GE Energy Smart...
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...
I'm a fan of using manufacturers catalogues. There are two main reasons for this. Firstly, if your involved in the purchase of equipment, you will likely...
The (relatively new) switchgear and control gear standard, IEC 61439 'Low-voltage switchgear and controlgear assemblies' has three methods which can be...
When selecting a cable, the performance of the cable under fault conditions is an important consideration. It is important that calculations be carried...
Current transformers (CTs) are used to convert high level currents to a smaller more reasonable level for use as inputs to protection relays and metering...
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 ...
Various techniques exist to enable the correct selection of batteries for UPS applications. The procedure described below is one of the more common. ...
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