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Statistics |
| Unique Visitors: 45 |
| Total Unique Visitors: 624841 |
| Visitors Out: 686 |
| Total Visitors Out: 1011 |
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| EMERGENCE OF SUPERCAPACITOR OR ULTRACAPACITOR |
| 2011-07-28 11:02:00 |
Supercapacitor or Ultracapacitor is technically an electrochemical double layer capacitor (EDLC). This technology is already gaining ground in challenging the Battery as the leading and preferred energy storage device. It exemplifies a large improvement from the common electrolytic capacitors, which are quick and powerful but energy poor. Meanwhile, supercapacitors are energy-rich storage devices whose first applications are likely to be in hybrid electric vehicles and backup power supplies....
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| POWER QUALITY BASICS: HARMONICS |
| 2011-07-26 09:19:00 |
Harmonics are described by IEEE as sinusoidal voltages or currents having frequencies that are integer multiples of the fundamental frequency (e.g. 50 Hz, 60 Hz) at which the power system is designed to operate. They combine with the fundamental voltage or current producing a non-sinusoidal shape, thus, a waveform distortion power quality problem. The non-sinusoidal shape corresponds to the sum of different sine waves with different magnitude and phase angles, having frequencies that are...
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| SINGLE-PHASING ON TRANSFORMER SECONDARY |
| 2011-07-23 13:24:00 |
Single-phasing occurs when one phase of a three-phase system is intentionally or accidentally opened. It is considered as the worst case of Voltage Unbalance and can either be in the primary side or secondary side of a distribution transformer. However, this post will only discuss single-phasing on the secondary side of the transformer.
Secondary single-phasing can be very damaging to electrical loads, especially three-phase motors. The connected equipment will be subjected to damaging...
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| SWITCHED MODE POWER SUPPLY (SMPS) FOR ELECTRONICS APPLICATIONS |
| 2011-07-21 00:23:00 |
Switched Mode Power Supply (SMPS), sometimes called Switcher is gaining popularity in the last decade or so. The SMPS is more efficient and lighter in weight as compared to its conventional counterpart, the linear power supply.
Generally, electronic circuits require a direct current (DC) voltage source in order to operate - typically 3 to 12 volts. Therefore, every electronic device that is connected from the AC mains should include a circuit that will derive a stable DC voltage from the 120...
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| ELECTROSTATIC DISCHARGE (ESD) PROCESS AND PROTECTION |
| 2011-07-15 01:18:00 |
Electrostatic Discharge (ESD) is a form of an impulsive transient exhibited by the rapid and momentary flow of electrostatic charge two things that are at different potentials. Generally, this sudden discharge of static electricity does not harm the human body, but it can create several problems such as damaged electronic components, equipment downtime, safety concerns and material handling issues in the manufacturing and production facilities. Also, it is possible for electronic devices to be...
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| UNDERSTANDING SERIES CAPACITORS |
| 2011-07-01 00:06:00 |
Series Capacitors are generally applied to compensate the excessive inductance of long transmission lines, in order to reduce the line voltage drop, improve its voltage regulation, minimize losses by optimizing load distribution between parallel transmission lines, and to increase the power transfer capability. Similarly, series capacitors are also installed in electrical power systems to improve its voltage stability.
In contrast to a shunt capacitor, series compensation results in a voltage...
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| SHUNT CAPACITORS AND THEIR APPLICATIONS |
| 2011-06-29 01:22:00 |
Shunt Capacitors have several uses in the electric power systems. They are utilized as sources of reactive power by connecting them in line-to-neutral. Electric utilities have also connected capacitors in series with long lines in order to reduce its impedance. This is particularly common in the transmission level, where the lines have length in several hundreds of kilometers. However, this post will generally discuss shunt capacitors.
Shunt capacitors are usually called “power factor...
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| POWER QUALITY BASICS: VOLTAGE UNBALANCE |
| 2011-06-20 08:54:00 |
Voltage Unbalance (or Imbalance) is defined by IEEE as the ratio of the negative or zero sequence component to the positive sequence component. In simple terms, it is a voltage variation in a power system in which the voltage magnitudes or the phase angle differences between them are not equal. It follows that this power quality problem affects only polyphase systems (e.g. three-phase).
Voltages are rarely exactly balanced between phases. However, when voltage unbalance becomes excessive, it...
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| DYNAMIC VOLTAGE RESTORER (DVR) |
| 2011-06-13 08:23:00 |
DVR (Dynamic Voltage Restorer) is a static var device that has seen applications in a variety of transmission and distribution systems. It is a series compensation device, which protects sensitive electric load from power quality problems such as voltage sags, swells, unbalance and distortion through power electronic controllers that use voltage source converters (VSC).
The first DVR was installed in North America in 1996 - a 12.47 kV system located in Anderson, South...
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| PSCAD – THE ELECTROMAGNETIC TRANSIENTS SOFTWARE |
| 2011-06-03 03:59:00 |
PSCAD (Power Systems Computer Aided Design) is a time domain simulation software for analyzing transients in electrical networks. It is a collection of programs, providing a graphical Unix-based user interface to electromagnetic transients program (EMTP). It is also known as PSCAD/EMTDC. EMTDC (Electromagnetic Transients with DC Analysis) was first developed in 1976 and has been constantly evolving in its scope and capabilities. It is an integral part of PSCAD as it is the library of power...
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