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 ...

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...

ABB has produced a range of technical guides that offer concise explanations of the major technologies and technical issues in low voltage AC drives. ...

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...

This is the first of two posts on the resistance of conductors. In the next post I will look at the ac resistance, including skin effect and we deal with...

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

Motor starting and its associated problems are well-known to many people who have worked on large industrial processes. However, these things are, of course...

The International System of Units (abbreviated SI) is the world's most widely used system of units.  The system consists of a set of units and prefixes...

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...

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...