Power systems theory - generation, transmissions and distribution
Photovoltaic (PV) systems are typically more efficient when connected in parallel with a main power gird. During periods when the PV system generates energy this can be utilized and the grid energy u... read more..
Per unit fault calculations is a method whereby system impedances and quantities are normalised across different voltage levels to a common base. By removing the impact of varying voltages, the... read more..
For unbalance conditions the calculation of fault currents is more complex. One method of dealing with this is symmetrical components. Using symmetrical components, the unbalance system is broken dow... read more..
In the previous note we looked at the approach taken by the standard to the sizing of cables and illustrated this with an example. We then looked at one method of applying the standard and iden... read more..
Current transformers (CTs) are used to convert high level currents to a sma... read more..
IEC 60287 "Calculation of the continuous current rating of cables (100% load factor)" is the International Standard which defines the procedures and equations to be used in determining the ... read more..
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 (id.c.). This initial dc compo... read more..
One of the fundamental requirements of an alternating current distribution systems it to have the ability to change the magnitude of voltages. It is more efficient to transmit power at high voltag... read more..
I've recently come across this question a couple times browsing the internet. Decided to give a quick answer here. A rectifier transformer is a transformer which includes diodes or thyristors in the sam... read more..
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 side. While this is easy for some people to... read more..
Electromagnetic compatibility (EMC) is the study of coordinating electromagnetic fields give off equipment, with the withstand (compatibility) of other equipment within the vicinity. In it's simplest... read more..
Installation of a UPS can help in reducing problems due to issues with the power supply. A lot of people relate this to nine key issues. Depending on the type of UPS installed it is possible... read more..
The other day I was talking to a colleague who is a building services consultant. Despite regularly specifying dry-type/cast resin transformers he was...
Current transformers (CTs) are used to convert high level currents to a smaller more reasonable level for use as inputs to protection relays and metering...
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...
Many questions sent in to the site are in connection with motor starting and in particular star-delta. For all but the simplest application, there is...
Straight forward list of some common motor faults. If I have missed any other common faults, please take a bit of time to add them in as a comment below...
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...
Bored at work and would rather be playing trump card game with you son. The next best thing (or not) maybe the online cable trump card game from AEI Cables...
Traditionally substations have used circuit breakers, current transformers (CT), voltage transformers (VT) and protection relays all wired together using...
The following tables provide quick order of magnitude fault levels for a a range of typical low voltage situations.
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...
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