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...
Arc Flash Calculations
Working in the vicinity of electrical equipment poses an hazard. In addition to electric shock hazard, fault currents passing through air causes Arc Flash...
Switchboard - Forms of Internal Separation
IEC 61439 'Low-voltage switchgear and controlgear assemblies', specifies standard arrangements of switchboard (call forms of internal separation). The...
What are you reading!
Reading is a bit of a hobby of mine and I"ve done a few off-topic posts in the past on this. Rather than continue doing the occasional post I thought ...
Dielectric loss in cables
Dielectrics (insulating materials for example) when subjected to a varying electric field, will have some energy loss. The varying electric field causes...
Batteries
A battery consists of one or more cells, each of which use stored chemical energy to produce electrical energy, There are many types of cells and these...
Capacitors - Energy Storage Application
Capacitors have numerous applications in electrical and electronic applications. This note examines the use of capacitors to store electrical energy....
The dc resistance of conductors
This is the first of two posts on the resistance of conductors. In the next post I will look at the ac resistance, including skin effect and we deal with...
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...
Fault Calculation - Symmetrical Components
For unbalance conditions the calculation of fault currents is more complex. One method of dealing with this is symmetrical components. Using symmetrical...