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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...

Lightning Protection and Earth Electrode Resistance

Most installations involve some form of lightning protection system which is connected to an earth electrode.  The function of the earth electrode is to...

Hazardous Areas – IEC and NEC/CEC Comparison

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

Mobile Phones (Brick to Implant)

The mobile phone was born in 1973. They were the size of a brick and weighed a couple of kg, making them difficult to fit into your pocket. At a few thousand...

What does N+1 mean?

The term 'N+1' relates to redundancy and simply means that if you required 'N' items of equipment for something to work, you would have one additional...

Alternating Current Circuits

Alternating current (a.c.) is the backbone of modern electrical power distribution. In this article I’ll be pulling some of the more important concepts...

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 ...

LED Replacement Light Bulb

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...

Low Voltage Fault Tables

The following tables provide quick order of magnitude fault levels for a a range of typical low voltage situations.

Fault Calculations - Typical Equipment Parameters

A frequent problem in fault calculations is the obtaining of equipment parameters.  While it is always preferable to use the actual parameters of the equipment...

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