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..
While there are a vast array of cable insulation materials, these are often divided into two general types; Thermoplastic or Thermosetting. For example...
The fundamental component of any analogue computer is the operational amplifier, or op amp. An operational amplifier (often called an op-amp,) is a high...
Power factor is the ratio between the real power (P in kW) and apparent power (S in kVA) drawn by an electrical load. The reactive power (Q in kVAr)...
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...
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...
Our IEE cable sizing was wrote a few years ago and had become rough around the edges. I thought it was time to give the tool a service. Unfortunately when...
The new standard IEC 61439 replaces the old 60439. Compared to the old standard, the new 61439 is a more clearly defined and takes into account the assembly...
Traditionally substations have used circuit breakers, current transformers (CT), voltage transformers (VT) and protection relays all wired together using...
Capacitors have numerous applications in electrical and electronic applications. This note examines the use of capacitors to store electrical energy....
Dielectrics (insulating materials for example) when subjected to a varying electric field, will have some energy loss. The varying electric field causes...
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