Blogs

I received this question by email a few weeks. First thoughts was that it is a product of the mathematics of rotating a straight conductor in a magnetic field. While I guess this is the primary issue, after some thinking I have come up with few reasons why a sinusoidal wave is advantageous:

ABB has produced a range of technical guides that offer concise explanations of the major technologies and technical issues in low voltage AC drives.  The technical guides cover subjects such as the basics of variable-speed drives, dimensioning a drive system, electrical braking, harmonics and AC drives, and bearing currents.

A couple of months ago I came Microsoft's OneNote and downloaded the 60 day free trail. Since then I have been using it regularly and now have a full license. If you don't know what OneNote is, the best way to see how it works is to download the free trail and have a go.

Microsoft's describes the software as:

Most installations involve some form of lightning protection system which is connected to an earth electrode.  The function of the earth electrode is to dissipate the lightning strike safely in to the ground.  Often the performance of the earth electrode is specified and verified by stating a maximum resistance and ensuring that the installed system meets this.  Resistance is easily understood and an easy property to measure.  However, it is only indicative of the performance of the earth electrode under lightning conditions.  Other parameters have a more signification effect.

A while ago I wrote a post on how myElectrical is put together. Since then there have been some changes and maybe its time to update the post.  Rather then edit the original I'm writing a new one to keep a sort of history of the site.  myElectrical was something I started a few years ago (sometime in 2002).  It started as a quick attempt at making some software available on-line and over the years the site has grown from a couple of pages to what it is now. 

I have recently been involved in a life cycle cost analysis for an electrical system and we needed to estimate the cable operating losses.  For the system model we used Amtech software.  While the software calculates cable losses it does not do it for busbars and it is also done in a non-transparent way.  To find a way around this it was back to to fundamentals. 

The IEC publishes a series of documents and rules governing the preparation of documents, drawings and the referencing of equipment.   Depending on country and industry, people are either familiar with the IEC system or not.  For those not familiar it can be a little confusing at first.

Often when IEC document production is compared to methods it is mistakenly assumed the difference is simply symbols.  This is not the case.  The IEC document and referencing system is a comprehensive approach covering symbols, drawing and layout techniques, equipment references, identification of terminals and signals, classification of documents and computer data organisation.   It also goes beyond just documentation and extends into physical devices and implementation. 

I've been considering a blog on the 110 or 230 Volt issue for a while.  While browsing the Internet I came across a great summary by Borat over at  engineering.com.  He summarises the issue as:

• Historical reasons. Edison insisted on 110 V (DC) but was convinced by Westinghouse to switch to AC so that transformers (step up/down) could be used. So that became the North American standard. In Europe AEG started with 110 V (following Edison) but at 50 Hz (instead of North American 60 Hz) because it fit neater into the metric system. After WWII the voltage was doubled to 220 V because higher voltages use less copper - which was at a premium. Other countries in the world usually followed the standards of their colonizing powers. The proliferation of 110 V receptacles and devices in North America prevented the doubling of voltage but that is one of the reasons your large appliances use 220-240V plugs.