Voltage Levels – Confused?
I was having a conversation the other day about voltage levels. While everyone was in agreement that low voltage was 1000 V and less, there was more confusion...
Low Voltage Fault Tables
The following tables provide quick order of magnitude fault levels for a a range of typical low voltage situations.
Photovoltaic (PV) - Utility Power Grid Interface
Photovoltaic (PV) systems are typically more efficient when connected in parallel with a main power gird. During periods when the PV system generates energy...
Lightning Protection and Earth Electrode Resistance
Most installations involve some form of lightning protection system which is connected to an earth electrode. The function of the earth electrode is to...
Understanding Motor Duty Rating
One of the comments on my Motor Starting Series was asking for something on duty cycles. Here it is.
As a purchaser of a motor, you have responsibility...
DC Motor Operation
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...
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...
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...
DC Component of Asymmetrical Faults
The image (reproduced from IEC 60909) shows a typical fault in an ac system. From the illustration it can seen that there is an initial dc component ...
Meeting room of the future
The IET site has a video of a visit showing of a high tech meeting room developed at Napier University in Edinburgh. It a good demonstration of innovative...