Opinion

Welcome back Bottle

By Steven on 10/9/2011 8:23 AM | Filed Under [Off Topic]
Popular tags: Fiction

‘Kept looking at a card, y’see? Kept looking at it. Welcome back Bottle. Gods below welcome home.

The Crippled God
A Tale of the Malazan Book of the Fallen 10, Steven Erikson

If you recognise the quote then you already know what an exciting journey this series by Steven Erickson is. If not then the only thing I really need to say is that you must read the series.

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Motor Starting - Rotor Resistance

By Steven on 10/6/2011 7:01 AM | Filed Under [Electrical Engineering], [Power Systems], [Control & Automation]
Popular tags: Motor Starting

2 Comments

Rotor resistance starting is the second starting method to discuss involving the addition of resistors into the external circuit. In this case the resistors are connected into the rotor circuit. This is also the only method I’ll be discussing where you need to get access to the rotor windings; consequently a standard squirrel cage motor cannot be used and a slip-ring motor is required.

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Differential protection, the good old days

By Steven on 10/3/2011 7:52 AM | Filed Under [Electrical Engineering], [Power Systems]
Popular tags: Protection

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This morning I was explaining how differential protection works to a junior engineer. To give him something to read I opened up the NPAG (Network Protection and Automation Guide, by Areva) and turned to Chapter 10 ‘Unit Protection of Feeders’. I was immediately confronted with Marz and Price, circulating current systems, balanced voltage systems, high impedance series connected relays, illustration like the attached, etc. ... and remembered my early years. A time when if you mentioned differential protection to an electrical engineer, they would turn and run in the opposite direction.

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Motor Starting - Primary Resistance

By Steven on 9/29/2011 2:18 AM | Filed Under [Electrical Engineering], [Power Systems], [Control & Automation]
Popular tags: Motor Starting

6 Comments

So far we have looked at direct on line starting and reduced voltage methods of starting, (star-delta and auto-transformer). In this post we start on starting methods which rely on the use of resistors to limit the current. Primary resistance starting is concerned with the introduction of resistance into the stator windings. Rotor resistance, which I will discuss in the next post is concerned with the introduction of resistance in the motor rotor. Resistors inserted into the primary of the motor increase the overall impedance of the circuit and reduce the starting current.

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Voltage Drop in Installations - Concepts

By Steven on 9/27/2011 1:50 AM | Filed Under [Electrical Engineering], [Buildings Technology]
Popular tags: Voltage Drop

4 Comments

Problems on achieving maximum voltage drop within an installation come up often. Depending where you live, local regulations will have different limits on maximum allowable voltage drop, however the intent of all of these is to ensure sufficient voltage is available at the equipment so that if functions correctly. Specified voltage drops are generally not for an individual cable but for the full installation; from the point of supply connection to the final equipment. Thus the overall voltage drop is a combination of individual voltage drops across multiple cables.

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New Mail Chimp

By Steven on 9/26/2011 12:54 AM | Filed Under [myElectrical]
Popular tags: Newsletter, myElectrical

0 Comments

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 is a fantastic product (and free of cost), to improve our Newsletter delivery we have changed to a paid service. All Newsletter and update emails are now being delivered by mailChimp (http://mailchimp.com).

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Motor Starting - Auto-Transformer

By Steven on 9/22/2011 2:07 AM | Filed Under [Electrical Engineering], [Power Systems], [Control & Automation]
Popular tags: Motor Starting

4 Comments

Like star-delta starting, the use of an auto-transformer is a reduced voltage starting method. Unlike star-delta which forces a fixed reduction in voltage, the use of an auto-transformer enables almost any range of voltage to be considered during the starting period. Given tapping's on the transformer, the voltage can be varied through the stating period. The ability to vary the level of voltage applied during stating not only allows the starting current to be constrained within limits, but also allows for closer matching of the starting torque to the mechanical requirements. The major downside (at least compared to star-delta) is the increased cost due to the auto-transformer.

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Back to the future

By Steven on 9/18/2011 6:29 AM | Filed Under [myElectrical]
Popular tags: CPD, myElectrical

0 Comments

Now that the heading has got your attention, I probably need to disappoint you; this is not a post about travelling through time or how to harness the power of lightning to drive clocks. Instead it’s on the more mundane subject of classifying our site content according to knowledge and skill levels. This is something I planned to do in the future, wanted to set up the ground work now (and while writing this post have implemented some of it).