From the monthly archives: November 2011

We are pleased to present below all posts archived in 'November 2011'. If you still can't find what you are looking for, try using the search box.

How to Size Power Cable Duct

By Steven McFadyen on 11/24/2011 10:09 AM

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 a clear idea on an approved method. In the end w... read more..


How to Calculate Motor Starting Time

By Steven McFadyen on 11/15/2011 2:00 PM

Request to look at induction motor starting time have come up a few times on the site. Hopefully in this post, I give you guys some idea on how to calculate this. Failing that, hopefully at least som... read more..


Difference Between Live and Dead Tank Circuit Breakers

By Steven McFadyen on 11/11/2011 10:51 AM

A quick post in connection with an email question:

Live Tank - the circuit breaker the switching unit is located in an insulator bushing which is live at line voltage (or some voltage above g... read more..


How to Size Current Transformers

By Steven McFadyen on 11/7/2011 11:48 AM

The correct sizing of current transformers is required to ensure satisfactory operation of measuring instruments and protection relays. Several methods exist to size current transformers. This note will... read more..


How to Check a Circuit is Dead

By Steven McFadyen on 11/3/2011 4:46 AM

If you want to check a circuit is dead (not live), you should always use the three point method. First check a known live circuit, then check the dead circuit and finally recheck the live circuit. Carry... read more..




How to Calculate Motor Starting Time

Request to look at induction motor starting time have come up a few times on the site. Hopefully in this post, I give you guys some idea on how to calculate...

Maxwell's Equations - Introduction

Maxwell's Equations are a set of fundamental relationships, which govern how electric and magnetic fields interact. The equations explain how these fields...

EU Code of Conduct on Data Centres - Best Practices

The European Union is implementing a voluntary code of practice for participants with the aim of improving the overall efficiency of data centres. As part...

Introduction to Current Transformers

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...

Back to Basics - Ohm’s Law

Electrical engineering has a multitude of laws and theorems. It is fair to say the Ohm's Law is one of the more widely known; it not the most known. Developed...

How to refer fault levels across a transformer

Over the past year or so I've been involved in on going discussions related to referring fault levels from the secondary of a transformer to the primary...

Electric Motors

Collection of links to various places with useful motor information. I’ll try and return to the page every now and again to update it with any motor notes...

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...

UPS Battery Sizing

Various techniques exist to enable the correct selection of batteries for UPS applications.  The procedure described below is one of the more common. ...

The ac resistance of conductors

In a previous article I looked at the dc resistance of conductors and in this article we turn our attention to ac resistance. If you have not read the...

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