From the category archives: Electrical Fundamentals

Fundamental electrical engineering concepts and theory

Photovoltaic (PV) Panel - Performance Modelling

By Steven McFadyen on 1/8/2015 3:55 AM

In an earlier note on the site [Photovoltaic (PV) - Electrical Calculations], the theory of solar (PV) ... read more..


What is an Open Delta Transformer

By Steven McFadyen on 10/13/2014 11:54 AM

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 star, resulting in common transformer conf... read more..


Star-Delta Motor Starting - Performance

By Steven McFadyen on 7/10/2014 3:51 PM

Many questions sent in to the site are in connection with motor starting and in particular star-delta.  For all but the simplest application, there is merit in performing a more detailed study.&... 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..


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..


RLC Circuit, Resistor Power Loss - some Modelica experiments

By Steven McFadyen on 1/20/2014 1:32 PM

Modelica is an open source (free) software language for modelling complex systems. Having never used it before, I thought I would download a development platform and see how it stacked up.  This... read more..


Cable Sheath and Armour Loss

By Steven McFadyen on 10/13/2013 11:44 PM

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 in the sizing of cables.

This ... read more..


Maxwell's Equations - Gauss's Electric Field Law

By Steven McFadyen on 9/4/2013 3:47 PM

Gauss's Electrical law defines the relation between charge ("Positive" & "Negative") and electric field.  The law was initially formulated by Carl Friedrich Gauss in 1835.

In Gauss'... read more..


Maxwell's Equations - Introduction

By Steven McFadyen on 9/4/2013 2:33 PM

Maxwell's Equations are a set of fundamental relationships, which govern how electric and magnetic fields interact. The equations explain how these fields are generated and interact with each other, ... read more..


Capacitors - Energy Storage Application

By Steven McFadyen on 6/29/2013 8:24 PM

Capacitors have numerous applications in electrical and electronic applications.  This note examines the use of capacitors to store electrical energy.  The sidebar shows details of a typical c... read more..


Capacitor Theory

By Steven McFadyen on 6/12/2013 1:52 PM

Capacitors are widely used in electrical engineering for functions such as energy storage, power factor correction, voltage compensation and many others.  Capacitance is also inherent in any ele... read more..


Introduction to Cathodic Protection

By Steven McFadyen on 4/25/2013 12:53 PM

If two dissimilar metals are touching and an external conducting path exists, corrosion of one the metals can take place.  Moisture or other materials acting as an electrolyte between the metals... read more..


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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...

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...

What happened to the cable notes?

If you are wondering what happened to our cable notes, the short answer is that we have moved them to myCableEngineering.com.  The "Knowledge Base" at...

Cost Performance and Time

Often us engineers get so bogged down in equations, using software, producing drawings and writing specifications that this becomes the sole focus.   ...

Gas Insulated or Air Insulated Switchgear

Various arguments exist around SF6 Gas Insulated (GIS) and Air Insulated (AIS) medium voltage switchgear. Recently we had to change a GIS design to AI...

IEC 61439 - The Switchgear Standard

The new standard IEC 61439 replaces the old 60439. Compared to the old standard, the new 61439 is a more clearly defined and takes into account the assembly...

Load Flow Study – how they work

A load flow study is the analysis of an electrical network carried out by an electrical engineer. The purpose is to understand how power flows around...

Star-Delta Motor Starting - Performance

Many questions sent in to the site are in connection with motor starting and in particular star-delta.  For all but the simplest application, there is...

UPS - Uninterruptible Power Supply

A UPS is an uninterruptible power supply.  It is a device which maintains a continuous supply of electrical power, even in the event of failure of the...

How a Digital Substation Works

Traditionally substations have used circuit breakers, current transformers (CT), voltage transformers (VT) and protection relays all wired together using...

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