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

Three phase systems are derived from three separate windings, either connected in delta or star (wye). Each winding can be treated separately, leading...

This article gives an introduction to IEEE 485 method for the selection and calculation of battery capacity.

The correct sizing of current transformers is required to ensure satisfactory operation of measuring instruments and protection relays. Several methods...

The widely used United Sates standard ANSI/IEEE C37.2 'Electrical Power System Device Function Numbers, Acronyms, and Contact Designations' deals with...

The windings of many medium and small sized transformers are protected by restricted earth fault (REF) systems. The illustration shows the principal of...

When thinking about watts (W) or kilowatt (kW = 1000 W) it can be useful too keep in mind the fundamental ideas behind the unit. Watt is not a pure electrical...

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

Estimating maximum demand is a topic frequently discussed. Working out how much power to allow for a building can be very subjective . Allowing too much...

In the previous note we looked at the approach taken by the standard to the sizing of cables and illustrated this with an example.  We then looked at one...