From the monthly archives: July 2012

We are pleased to present below all posts archived in 'July 2012'. If you still can't find what you are looking for, try using the search box.

Fault Calculations - Typical Equipment Parameters

By Steven McFadyen on 6/24/2012 7:38 AM

A frequent problem in fault calculations is the obtaining of equipment parameters.  While it is always preferable to use the actual parameters of the equipment, sometimes these are not available... 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.

read more..


Questions - Reputation and Privilege

By Steven McFadyen on 6/15/2012 9:08 AM

Our question and answer system while letting you do exactly what it says, is much more.  It is a dynamic user driven system, where our users not only ask and answer questions, but can manage the... read more..


Inductance

By Steven McFadyen on 6/3/2012 11:08 AM

When current flows within a wire, a magnetic field is created. The potion of this magnetic field perpendicular to the wire is called the magnetic flux (measured in weber, Wb). Inductance is the ratio... read more..




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...

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...

Battery Cars A to Z

Battery powered cars are a hot topic and widely debated. The pros, cons, issues and time frames can be talked about endlessly. An article by the Telegraph...

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...

Restricted Earth Fault Protection

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

Aluminium Windings - Dry Type Transformers

The other day I was talking to a colleague who is a building services consultant.  Despite regularly specifying dry-type/cast resin transformers he was...

Meeting room of the future

The IET site has a video of a visit showing of a high tech meeting room developed at Napier University in Edinburgh. It a good demonstration of innovative...

Understanding electric motor insulation & temperature

Anyone specifying or using electric motors should have a basic understanding how the insulation is related to temperature. Three classes of insulation...

Voltage Levels – Confused?

I was having a conversation the other day about voltage levels.  While everyone was in agreement that low voltage was 1000 V and less, there was more confusion...

Tech Topics/Application Notes - Siemens

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...

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