Per unit fault calculations is a method whereby system impedances and quantities are normalised across different voltage levels to a common base.  By removing...

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...

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...

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  While over recent years these have been replaced by microprocessor...

Working in the vicinity of electrical equipment poses an hazard. In addition to electric shock hazard, fault currents passing through air causes Arc Flash...

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 ...

This post is quick introduction and overview to different railway electrification voltages used in answer to a question sent in via email. While there...

Insulation on a motor prevents interconnection of windings and the winding to earth.  When looking at motors, it is important to understand how the insulation...

Ever wondered what kind of power an aircraft uses when parked at the airport stand. Normally the aircraft generates it own power, but when parked with...

When sizing cables, the heat generated  by losses within any sheath or armour need to be evaluated. When significant, it becomes a factor to be considered...