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...

The correct sizing of current transformers is required to ensure satisfactory operation of measuring instruments and protection relays. Several methods...

The mobile phone was born in 1973. They were the size of a brick and weighed a couple of kg, making them difficult to fit into your pocket. At a few thousand...

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...

Various arguments exist around SF6 Gas Insulated (GIS) and Air Insulated (AIS) medium voltage switchgear. Recently we had to change a GIS design to AI...

Coils of wire on the rotor carry a d.c. current which generates a magnetic field. A stator magnetic field is created using either permanent magnets or...

Electrical notes are a collaborative collection of electrical engineering information and educational material. Any registered user can add content. ...

If two dissimilar metals are touching and an external conducting path exists, corrosion of one the metals can take place.  Moisture or other materials...

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 ...

Following on from my post on railway electrification voltages, I thought an introduction to traction substations would be a good idea. Traction substations...