#### The ac resistance of conductors

By Steven McFadyen on 1/11/2012 11:03 AM

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 previous article, now may be a good time to do so. ... read more..

#### Restricted Earth Fault Protection

By Steven McFadyen on 3/25/2012 7:49 AM

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

#### Cable Insulation Properties

By Steven McFadyen on 5/15/2012 1:13 AM

Cable insulation is used to provide electrical separation between conductors of  a cable.  During the historical development of cables, numerous types of insulation have been employed. ... read more..

#### Photovoltaic (PV) Panel - Performance Modelling

By Steven McFadyen on 1/7/2015 10:55 PM

In an earlier note on the site [Photovoltaic (PV) - Electrical Calculations], the theory of solar (PV) ... read more..

#### Three Phase Current - Simple Calculation

By Steven McFadyen on 3/1/2009 6:47 AM

The calculation of current in a three phase system has been brought up on our site feedback and is a discussion I seem to get involved in every now and again. While some colleagues prefer to remember... read more..

#### Load Flow Study – how they work

By Steven McFadyen on 12/8/2014 5:25 AM

A load flow study is the analysis of an electrical network carried out by an electrical engineer. The purpose is to understand how power flows around the electrical network. Carrying out a load flow s... read more..

#### Thermoplastic and Thermosetting Insulation

By Steven McFadyen on 7/5/2011 10:12 PM

While there are a vast array of cable insulation materials, these are often divided into two general types; Thermoplastic or Thermosetting. For example the current capacity determination of a cable in a... read more..

#### Arc Flash Calculations

By Steven McFadyen on 3/22/2012 2:14 AM

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 ar... read more..

#### Motor Starting - Introduction

By Steven McFadyen on 8/10/2011 8:28 PM

Motor starting and its associated problems are well-known to many people who have worked on large industrial processes. However, these things are, of course, less familiar to others.  This post ... read more..

#### Tips for a better Low Voltage Protection Discrimination Study

By Steven McFadyen on 11/3/2014 6:48 AM

Carrying out a protection system discrimination study is critical to ensure the correct functioning of  the electrical system in the event of faults.  The IEC defines discrimination as:

#### What is an Open Delta Transformer

By Steven McFadyen on 10/13/2014 6:54 AM

In three phase systems, the use of transformers with three windings (or legs) per side is common.  These three windings are often connected in delta or star, resulting in common transformer conf... read more..

#### Generator Sizing & Operation Limits

By Steven McFadyen on 11/1/2010 11:07 PM

When selecting a generator, there are inherent limits on the active and reactive power which can be delivered. Generators are normally sized for a certain kW at a power factor of 0.8. However, to unders... read more..

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