Notes

Electromagnetic Fields - Exposure Limits

By Steven McFadyen on 6/28/2014 6:00 PM

Exposure to time varying magnetic fields, from power frequencies to the gigahertz range can have harmful consequences. A lot of research has been conducted into identifying these effects and de... read more..

DC Component of Asymmetrical Faults

By Steven McFadyen on 1/9/2013 6:52 PM

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 (i_d.c.). This initial dc compo... read more..

Induction Motor Equivalent Circuit

By Steven McFadyen on 5/13/2014 1:19 PM

Induction motors are frequently used in both industrial and domestic applications. Within the induction motor, an electrical current in the rotor is induced by a varying magnetic field in the s... read more..

Photovoltaic (PV) - Electrical Calculations

By Steven McFadyen on 7/11/2013 2:46 PM

Photovoltaic (PV) cells (sometimes called solar cells) convert solar energy into electrical energy. Every year more and more PV systems are installed. With this growing application, it's ... read more..

How D.C. to A.C. Inverters Work

By Steven McFadyen on 4/22/2014 1:19 PM

Traditionally generation of electricity has involved rotating machines to produce alternating sinusoidal voltage and current (a.c. systems). With the development of power electronics during the last ... read more..

The dc resistance of conductors

By Steven McFadyen on 1/5/2012 2:14 PM

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 this. To get started, this post will look at the... read more..

How to Size Power Cable Duct

By Steven McFadyen on 11/24/2011 10:09 AM

Some colleagues had an issue earlier in the week on sizing conduits to be cast in concrete for some power cables . It became clear that none of us had a clear idea on an approved method. In the end w... read more..

How to Size Current Transformers

By Steven McFadyen on 11/7/2011 11:48 AM

The correct sizing of current transformers is required to ensure satisfactory operation of measuring instruments and protection relays. Several methods exist to size current transformers. This note will... read more..

Back to Basics - Ohm’s Law

By Steven McFadyen on 10/21/2011 2:02 PM

Electrical engineering has a multitude of laws and theorems. It is fair to say the Ohm's Law is one of the more widely known; it not the most known. Developed in 1827 by Georg Ohm the law defines the re... read more..

Alternating Current Circuits

By Steven McFadyen on 4/3/2012 1:29 PM

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 together. It is a work in progress and I’ll be add... read more..

Laplace Transform

By Steven McFadyen on 4/23/2012 2:05 PM

Laplace transforms and their inverse are a mathematical technique which allows us to solve differential equations, by primarily using algebraic methods. This simplification in the solving of equat... read more..

UPS Battery Sizing

By Steven McFadyen on 4/8/2012 1:36 PM

Various techniques exist to enable the correct selection of batteries for UPS applications. The procedure described below is one of the more common. It is also possible to use the IEEE 485 method ... read more..

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Back to Basics - Ohm’s Law

Electrical engineering has a multitude of laws and theorems. It is fair to say the Ohm's Law is one of the more widely known; it not the most known. Developed...

Write your best report

Years ago I was told that you should always try to write the best report you can. Many years later I still think on this as one of the better pieces of...

How to Write an Electrical Note

Electrical notes are a collaborative collection of electrical engineering information and educational material. Any registered user can add content. ...

Maxwell's Equations - Gauss's Electric Field Law

Gauss's Electrical law defines the relation between charge ("Positive" & "Negative") and electric field. The law was initially formulated by Carl Friedrich...

Cable Insulation Properties

Cable insulation is used to provide electrical separation between conductors of a cable. During the historical development of cables, numerous types...

What is an Open Delta Transformer

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...

How to Size Current Transformers

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

The ac resistance of conductors

In a previous article I looked at the dc resistance of conductors and in this article we turn our attention to ac resistance. If you have not read the...

International System of Units (SI System)

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...

Material Properties

Everything physical in electrical engineering from insulations to conductors revolves around materials. Here we are listing common materials along with...

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