From the category archives: Power Systems

Power systems theory - generation, transmissions and distribution

Fault Calculations - Introduction

By Steven McFadyen on 7/1/2012 10:45 AM

Fault calculations are one of the most common types of calculation carried out during the design and analysis of electrical systems. These calculations involve determining the current flowing through... read more..


Low Voltage Fault Tables

By Steven McFadyen on 6/24/2012 7:11 AM

The following tables provide quick order of magnitude fault levels for a a range of typical low voltage situations.

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Cable Sizing Tool

By Steven McFadyen on 5/20/2012 6:14 AM

Our cable sizing tool is one of the more popular tools on the site.  The tool enables cables to be sized in compliance with BS 7671 (the IEE Wiring Regulations) and by implication IEC 60364.

... read more..


Three Phase Power Simplified

By Steven McFadyen on 4/17/2012 2:00 PM

A single phase system is perhaps the most common type of system most people are familiar with. This is what people have in their homes and what appliances are plugged in to. For larger amounts of power,... read more..


Generation of a Sine Wave

By Steven McFadyen on 4/16/2012 1:57 PM

A fundamental concept behind the operation of alternating current systems is that voltage and current waveforms will be sinusoidal – a Sine Wave. This is best explained by considering how a coil of wire... read more..


Low Voltage Circuit Breakers

By Steven McFadyen on 4/15/2012 1:55 PM

Circuit breakers are switching devices whose primary function is to isolate parts of an electrical distribution system in the even of abnormal conditions.  Abnormal conditions are generally caused ... read more..


Battery Sizing

By Steven McFadyen on 4/8/2012 1:34 PM

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

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Variable Frequency Drive

By Steven McFadyen on 3/28/2012 9:58 PM

Variable frequency drives are widely used to control the speed of ac motors.  This note looks at the mechanisms which enable d... read more..


Motor Insulation

By Steven McFadyen on 3/28/2012 1:02 PM

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 functions and its practical applicatio... read more..


DC Motor Operation

By Steven McFadyen on 3/28/2012 1:00 PM

Coils of wire on the rotor carry a d.c. current which generates a magnetic field. A stator magnetic field is created using either permanent mag... read more..


Restricted Earth Fault Protection

By Steven McFadyen on 3/25/2012 12:49 PM

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


ANSI (IEEE) Protective Device Numbering

By Steven McFadyen on 3/22/2012 11:40 AM

The widely used United Sates standard ANSI/IEEE C37.2 'Electrical Power System Device Function Numbers, Acronyms, and Contact Designations' deals with protective device function numbering and acronyms. ... read more..




New Mail Chimp

We've been sending out Newsletters on a regular basis for a few weeks now. To do this we have been using Google's Feedburner service. While Feedburner...

A mechanical engineering paper, some history and memories

I was digging in my bookshelf and came across the 80th Anniversary Association of Mine Resident Engineers, Papers and Discussions Commemorative Edition...

Software Usage Guidelines

Using software in our  work is essential for most of us and we are becoming even more dependant on it's use.  While software is a great asset, many times...

Variable Frequency Drive

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...

Understanding Motor Duty Rating

One of the comments on my Motor Starting Series was asking for something on duty cycles. Here it is. As a purchaser of a motor, you have responsibility...

Earth Electrode Resistance

Earthing of electrical systems is essential for the correct functioning and the protecting of life and equipment in the event of faults.  The earth electrode...

IEC 61439 Verification Methods

The (relatively new) switchgear and control gear standard, IEC 61439 'Low-voltage switchgear and controlgear assemblies' has three methods which can be...

Post Authorship

In 2011, with the introduction of it’s Panda search ranking algorithms, Google introduced tools for determining the original author of posts.  The intention...

How to Size Power Cable Duct

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...

Bows and Arrows

It starts with me reading one of the Horrible History books with my son (Groovy Greeks). Arrows were mentioned which lead to the discussion of the bodkin...

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