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...

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...

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

These lifts were first built in 1884 by J. E. Hall and called a paternoster ("Our Father", the first two words of the Lord's Prayer in Latin) due to its...

A UPS is an uninterruptible power supply.  It is a device which maintains a continuous supply of electrical power, even in the event of failure of the...

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

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 post is quick introduction and overview to different railway electrification voltages used in answer to a question sent in via email. While there...

In 2011, with the introduction of it’s Panda search ranking algorithms, Google introduced tools for determining the original author of posts.  The intention...

I have been thinking recently that there appears to be less professional integrity around than when I first started my career in electrical engineering...