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Posted on 3/22/2012 11:35 AM By Steven McFadyen
Here’s list of some famous scientists. Deliberately short, with the aim to provide a quick memory jog or overview. If your looking for more detailed information, Google and Wikipedia have tons of it.
Posted on 3/22/2012 6:14 AM By Steven McFadyen
Working in the vicinity of electrical equipment poses an hazard. In addition to electric shock hazard, fault currents passing through air causes Arc Flash. To protect people a risk analysis on the arc flash hazard is carried out to better understand what may occur.
When evaluating arc flash there are two main considerations, 1) the incident energy in the arc flash and 2) flash protection boundary. I will be looking at the calculation of these two parameters in terms of IEE Std. 1584 'IEEE Guide for Performing Arc-Flash Hazard Calculations'.
Posted on 3/15/2012 7:27 AM By Steven McFadyen
When making adding a Note to our site we have a great online WYSIWYG editor and things are pretty simple. However, if you prefer you can write, manage and publish your posts using any external editor which implements the MetaWeblog API. A popular free post editor is Microsoft’s Windows Live Writer.
Posted on 3/13/2012 6:21 AM By Steven McFadyen
There are a lot of interesting two page type notes on various medium voltage topics – switchgear, circuit breakers, bus systems etc. It is on the Siemens US site, so many of he note are IEEE/ANSI based. Each topic discusses the standards, application and gives some advice on how to do thing.
Posted on 3/9/2012 11:39 AM By Steven McFadyen
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.
Posted on 3/3/2012 3:33 PM By Steven McFadyen
The (relatively new) switchgear and control gear standard, IEC 61439 'Low-voltage switchgear and controlgear assemblies' has three methods which can be used to verify the characteristics of an assembly will meet the standard. These are verification by test, verification by calculation and verification by the use of design rules.
The following table (table D.1 from Annex D of the standard)summarizes each characteristic and the allowable options for verification:
Posted on 3/3/2012 12:57 PM By Steven McFadyen
Lead acid batteries are cost effect and reliable, making them suitable for many applications.This note examines topics of interest associated with the use of these batteriesLead acid batteries are cost effect and reliable, making them suitable for many applications.This note examines various topics associated with the use of these batteries.
Posted on 2/26/2012 12:16 PM By Steven McFadyen
Following on from my post on railway electrification voltages, I thought an introduction to traction substations would be a good idea. Traction substations are used to convert electrical power as supplied by the power utility (or rail operators own network) to a form suitable for providing power to a rail system (via third rail or overhead line). Depending on the type of rail system this power would be either direct current (dc) or alternating current (ac).
Posted on 2/14/2012 11:43 AM By Steven McFadyen
If your are ever called out to troubleshoot something on your electrical system, one of the first things consider is the supply voltage. You want to ensure you have a good electrical supply before moving on to other possible problem causes. Here are a few things you can quickly measure to get an impression on the quality of supply:
Posted on 2/8/2012 5:35 AM By Steven McFadyen
I'm a fan of using manufacturers catalogues. There are two main reasons for this. Firstly, if your involved in the purchase of equipment, you will likely need to look into catalogues to find what you need. If your involved in design or specification you should also be looking into catalogues. I'm a big believer that any engineer should not be specifying an item of equipment unless the y have at least one product in mind which would fit the bill.
Posted on 2/2/2012 1:15 PM By Steven McFadyen
Just added a page to the tools, which will allow you to calculate the synchronous speed, slip and rated torque for an induction motor. Not a particularly complicated calculation, but anything the makes life easier is welcome.
Induction Motor Calculator
Posted on 1/29/2012 12:57 PM By Steven McFadyen
IEC 61439 'Low-voltage switchgear and controlgear assemblies', specifies standard arrangements of switchboard (call forms of internal separation).
The are labelled as Form 1, Form 2, Form 3 and Form 4. Forms 2, 3 and 4 are further broken down into Form 2a, 2b, 3a, 3b, 4a and 4b. Each Form relates to the internal separation of the busbars, functional units and terminals, each being defined as: