Notes

Fault Calculation - Symmetrical Components

Steven McFadyen — Wed, 27 Mar 2013 12:52:00 GMT

For unbalance conditions the calculation of fault currents is more complex. One method of dealing with this is symmetrical components. Using symmetrical components, the unbalance system is broken down in to three separate symmetrical systems:

Hazardous Areas – IEC and NEC/CEC Comparison

Steven McFadyen — Fri, 09 Mar 2012 11:39:00 GMT

Depending where in the world you work, you are likely following one of two standards

International Electrotechnical Commission (IEC)
National Electrical Code/Canadian Electrical Code (NEC/CEC)

The different nature of the two systems make a direct comparison almost impossible. If you do need to work with both systems or transition from one to the other, hopefully the following will make this easier.

Maxwell's Equations - Gauss's Electric Field Law

Steven McFadyen — Wed, 04 Sep 2013 14:47:00 GMT

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's law, the electric field is the electrostatic field. The law shows how the electrostatic field behaves and varies depending on the charge distribution within it. More formally it relates the electric flux [the electric field flowing from positive to negative charges] passing through a closed surface to the charge contained within the surface.

Introduction to Current Transformers

Steven McFadyen — Fri, 08 Feb 2013 11:17:00 GMT

Current transformers (CTs) are used to convert high level currents to a smaller more reasonable level for use as inputs to protection relays and metering equipment. Within electrical systems, current transformers are essential to ensure the correct functioning and control of equipment and for providing operational data and information.

This introductory note looks at the construction of current transformers and their specification

Dielectric loss in cables

Steven McFadyen — Tue, 12 Nov 2013 05:19:00 GMT

Dielectrics (insulating materials for example) when subjected to a varying electric field, will have some energy loss. The varying electric field causes small realignment of weakly bonded molecules, which lead to the production of heat. The amount of loss increases as the voltage level is increased. For low voltage cables, the loss is usually insignificant and is generally ignored. For higher voltage cables, the loss and heat generated can become important and needs to be taken into consideration.

What happened to the cable notes?

Steven McFadyen — Sat, 05 Aug 2017 14:00:00 GMT

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 myCableEgineering.com have tonnes of useful technical information on power cables. By adding our myElectrical cable notes, this resource, it is now even better.

Cable Sizing Software

Steven McFadyen — Fri, 21 Oct 2016 11:31:00 GMT

When sizing cables nearly, everyone uses some form of software. This ranges from homespun spreadsheets to complex network analyses software. Each has its advantages and disadvantages.

Three Phase Current - Simple Calculation

Steven McFadyen — Sun, 01 Mar 2009 11:47:00 GMT

The calculation of current in a three phase system has been brought up on our site feedback and is a discussion I seem to get involved in every now and again. While some colleagues prefer to remember formulas or factors, I prefer to resolve the problem step by step using basic principles. I thought it would be good to write how I do these calculations and hopefully it may prove useful to someone else.

Motor Efficiency Classification

Steven McFadyen — Wed, 28 Mar 2012 13:05:00 GMT

Electric motors are one of the most widely used items of electrical equipment. Improving motor efficiency benefits include, reduced power demand, lower operating costs and reduced environment impact.

In recognising the impact of motors on both power generation requirements and environmental issues, regulation in many countries now dictate efficiency limits. When specifying motors, both designers and purchasers should be concerned with efficiency performance.

Maximum Demand for Buildings

Steven McFadyen — Wed, 16 Jun 2010 16:42:00 GMT

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 power results in additional equipment, increased space requirements, greater system losses and extra cost. On the other side, no enough power results in operational problems. Trying to find the right amount of power is like gazing into a crystal ball and everyone will see something different.