Protection
Transformer and Transformer-Feeder Protection
The development of modern power systems has been reflected in the advances in transformer design. This has resulted in a wide range of transformers with sizes ranging from a few… Read more
Nov 30, 2011 | By Edvard
Energy and Power
Overvoltages Caused by Direct Lightning Strokes
A lightning stroke is defined as a direct stroke if it hits either the tower or the shield wire or the phase conductor. This is illustrated in Figure 1. When… Read more
Nov 29, 2011 | By Edvard
Transmission and Distribution
What is the reason beyond three phase transmission?
As the need for increased transmission line capacity have forced power utility and owner to maximize power density in existing transmission corridors. Many experienced have already been done on this,… Read more
Nov 28, 2011 | By Edvard
Electronics
Power Semiconductor Device – MOSFET
Power MOSFETs are marketed by different manufacturers with differences in internal geometry and with different names such as MegaMOS, HEXFET, SIPMOS, and TMOS. They have unique features that make them… Read more
Nov 27, 2011 | By Edvard
Electric Motor
Why do we need variable speed drives (VSD)?
There are many and diverse reasons for using variable speed drives. Some applications, such as paper making machines, cannot run without them while others, such as centrifugal pumps, can benefit… Read more
Nov 25, 2011 | By Edvard
Electronics
A Look at the Power Rating of Resistors
You may be asked: “what is the power rating of the resistors you want to buy?” when buying a resistor to build a certain circuit. For the most standard class… Read more
Nov 24, 2011 | By elaina
Electric Motor
Motors And Drives For Efficient Control – ABB
With electric motors accounting for an estimated 65 percent of industrial energy use, any increases in efficiency clearly provide the potential for major savings. The energy consumption of electric motors… Read more
Nov 23, 2011 | By Edvard
Cables
Fire Properties Of Cables
This is an area of increasing public and legislative concern, and therefore of increasing interest to engineers. There have been major advances in the fire performance of cables in recent… Read more
Nov 21, 2011 | By Edvard
Cables
Direct high voltage testing of cable insulation systems
DC testing has been accepted for many years as the standard field method for performing high-voltage tests on cable insulation systems. Whenever DC testing is performed, full consideration should be… Read more
Nov 19, 2011 | By Edvard
Cables
Partial Discharge Testing On Power Cable Systems
Partial discharge measurement is an important method of assessing the quality of the insulation of power cable systems, particularly for extruded insulation materials. This article considers partial discharge from two… Read more
Nov 18, 2011 | By Edvard
High Voltage
North American versus European distribution systems
Distribution systems around the world have evolved into different forms. The two main designs are North American and European. For both forms, hardware is much the same: conductors, cables, insulators,… Read more
Nov 17, 2011 | By Edvard
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What Standards To Use For Transformer Oil Testing?
ASTM (American Society for Testing and Materials) has developed the standards for oil testing. The following tests we recommended for a complete analysis of a transformer’s oil: The dielectric breakdown…...
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Nov 15, 2011 | By Edvard
Energy and Power
Demand Factor-Diversity Factor-Utilization Factor-Load Factor
Originally published at Electrical Notes – Articles Demand Factor = Maximum demand of a system / Total connected load on the system Demand factor is always less than one. Example:… Read more
Nov 14, 2011 | By jiguparmar
Energy and Power
Moving Iron Instruments – Voltmeter and Ammeter
Moving-iron instruments are generally used to measure alternating voltages and currents. In moving-iron instruments the movable system consists of one or more pieces of specially-shaped soft iron, which are so… Read more
Nov 13, 2011 | By Bipul Raman
High Voltage
High-voltage transmission lines and Electromagnetic Interference (EMI)
The corona discharge produces radio noise and in lesser extent television ( TV ) disturbances around high-voltage transmission lines. This can be easily observed by all of us when we… Read more
Nov 12, 2011 | By Edvard
