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Monthly Archive for: «November, 2010»

Wind Variability

One of the most critical features of wind generation is the variability of wind. Wind speeds vary with time of day, time of year, height above ground, and location on the earth’s surface. This makes… Read more

Nov 30, 2010 | Edvard

wind_turbines_farm-big

Danfoss – Max uptime for wind turbines

Located on top of towers that can extend 80 to 110 meters into the air, wind turbines are subjected to powerful operating forces. And because wind turbines are difficult to access for maintenance and repair,… Read more

Nov 29, 2010 | Edvard

danfoss-sensors

ABB invests in renewable energy company

Zurich, Switzerland, November 24, 2010 – ABB, the global power and automation technology group, announced today it has invested about $13 million in Aquamarine Power, a Scottish company that has developed technology to convert energy… Read more

Nov 29, 2010 | Edvard

waves

Transformer Cooling Classes

Since no transformer is truly an “ideal” transformer, each will incur a certain amount of energy loss, mainly that which is converted to heat. Methods of removing this heat can depend on the application, the… Read more

Nov 28, 2010 | Edvard

Transformer Cooling Classes

Should You Invest in Solar Power?

Solar power is quickly gaining popularity all over the globe. It is growing at a rate of 2% per year, and if the figures continue to grow, solar energy will be the preferred source of… Read more

Nov 27, 2010 | Edvard

solar-invest

Electrical Power System Overcurrents

Electrical power systems must be designed to serve  a variety of loads safely and reliably. Effective  control of short-circuit current, or fault current as  it is commonly called, is a major consideration  when designing coordinated… Read more

Nov 27, 2010 | Edvard

Megger Tests

The insulation resistance meter test method for determining the condition of electrical insulation has been widely used for many years as a general nondestructive test method. A serious limitation of this test is that its… Read more

Nov 26, 2010 | Edvard

Megger

Harmonic Distortion

Harmonic distortion is caused by nonlinear devices in the power system. A nonlinear device is one in which the current is not proportional to the applied voltage. Figure 1 illustrates this concept by the case… Read more

Nov 23, 2010 | Edvard

harmonic_distortion

Battery monitoring and maintenance guidelines

Battery monitoring has become a very popular topic, and many companies have either purchased equipment or are in the process of evaluating these systems. This article discusses why monitoring is important, and what parameters must… Read more

Nov 21, 2010 | Edvard

Battery Monitoring And Maintenance

The Need for Reactive Power Compensation

Except in a very few special situations, electrical energy is generated, transmitted, distributed, and utilized as alternating current (AC). However, alternating current has several distinct disadvantages. One of these is the necessity of reactive power… Read more

Nov 19, 2010 | Edvard

Power Factor Correction

ABB – 145kV Compact indoor substation with Disconnecting CB

Turnkey 145 kV S/S project for Borlänge Energi, Sweden, emphasizing the advantages of ABB Disconnecting Circuit Breakers. Small footprint enables indoor air insulated Switchgear solutions, increasing the power substation availability and reliability for the customer…. Read more

Nov 15, 2010 | Edvard

Distance Relays

Distance relays respond to the voltage and current, i.e., the impedance, at the relay location. The impedance per mile is fairly constant so these relays respond to the distance between the relay location and the… Read more

Nov 12, 2010 | Edvard

Distance relays

Gas-Insulated Substations – GIS

A gas-insulated substation (GIS) uses a superior dielectric gas, SF6, at moderate pressure for phase-tophase and phase-to-ground insulation. The high voltage conductors, circuit breaker interrupters, switches, current transformers, and voltage transformers are in SF6 gas… Read more

Nov 10, 2010 | Edvard

Gas-Insulated Substations - GIS

Emergency lights

Indepandant emergency supply Many buildings must have some form of emergency lighting to come on if the electric supply to the ordinary lights fails. BS 5266: Emergency lighting, BS EN 1838, BS 5266–7: Lighting applications…. Read more

Nov 10, 2010 | Edvard

Emergency lights

Oil-Filled, Inert-Gas System

A positive seal of the transformer oil may be provided by an inert-gas system. Here, the tank is slightly pressurized by an inert gas such as nitrogen. The main tank gas space above the oil… Read more

Nov 08, 2010 | Edvard

Oil transformer


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