tag:blogger.com,1999:blog-69074657500362343582011-11-28T08:23:29.045+07:00HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comBlogger241100tag:blogger.com,1999:blog-6907465750036234358.post-18933079055070665802010-09-02T16:01:00.003+07:002010-09-02T16:39:00.381+07:00

The relationship between magnetism and electrical current was discovered and documented by Oerstad in 1819. He found that if an electric current was caused to flow through a conductor that a magnetic field was produced around that conductor. In 1831, Michael Faraday discovered that if a conductor is moved through a magnetic field, an electrical voltage is induced in the conductor. The magnitude

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-88671085079562908682010-08-17T16:40:00.004+07:002010-09-02T16:48:27.895+07:00

Essentially, there are two basic types of generators:• DC generators • AC generators: Asynchronous (Induction) generators and Synchronous generators INDUCTION GENERATORSThe induction generator is nothing more than an induction motor driven above its synchronous speed by an amount not exceeding the full load slip the unit would have as a motor. Assuming a full load slip of 3%, a motor with a

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-27157003465429624452010-06-21T19:21:00.002+07:002010-06-21T19:27:24.158+07:00

Benjamin Franklin is known for his discovery of electricity. Born in 1706, he began studying electricity in the early 1750s. His observations, including his kite experiment, verified the nature of electricity. He knew that lightning was very powerful and dangerous. The famous 1752 kite experiment featured a pointed metal piece on the top of the kite and a metal key at the base end of the kite

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-2399641618938737592010-06-19T10:58:00.002+07:002010-06-19T11:04:14.733+07:00

The selection of a suitable starting method for a motor/load combination is becoming increasingly important as additional loads are added to existing utility and distribution systems. In the past, ample capacities were available in the utility networks to support the needs of industry. As well, the distribution systems of most North American industries were established during the industrial and

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-82416734157154849852010-06-19T10:40:00.003+07:002010-06-19T11:05:42.011+07:00

When large motors are started, noticeable voltage dips or flicker can occur on the consumers wiring system, the utility’s system, or both. Depending on the voltage sensitivity of other connected loads, these voltage dips can be unnoticeable, annoying, or harmful to the equipment. For example, lightbulbs can dim and be annoying to office personnel; however, voltage dips can cause other motor loads

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-73075987786756105622010-04-27T01:46:00.002+07:002010-04-27T01:53:21.691+07:00

A tap changer is a device fitted to power transformers for regulation of the output voltage to required levels. This is normally achieved by changing the ratios of the transformers on the system by altering the number of turns in one winding of the appropriate transformer/s. Supply authorities are under obligation to their customers to maintain the supply voltage between certain limits. Tap

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-66327755327134434742010-02-04T02:16:00.005+07:002010-02-04T02:26:56.693+07:00

As was mentioned before, the angle of this “power triangle” graphically indicates the ratio between the amount of dissipated (or consumed) power and the amount of absorbed/returned power. It also happens to be the same angle as that of the circuit's impedance in polar form. When expressed as a fraction, this ratio between true power and apparent power is called the power factor for this circuit.

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-30577573730964841512009-12-21T19:30:00.007+07:002009-12-21T20:41:19.846+07:00

Voltage TransformersA Transformer does not generate electrical power, it transfers electrical power. A transformer is a voltage changer. Most transformers are designed to either step voltage up or to step it down, although some are used only to isolate one voltage from another. The transformer works on the principle that energy can be efficiently transferred by magnetic induction from one winding

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-79407224230739135942009-12-21T19:25:00.002+07:002009-12-21T20:46:16.230+07:00

Due to the high cost of transmitting electricity at low voltage and high current levels, transformers fulfill a most important role in electrical distribution systems. Utilities distribute electricity over large areas using high voltages, commonly called transmission voltages. Transmission voltages are normally in the 35,000 volt to 50,000 volt range. We know that volts times amps equals watts,

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-22281454663447850682009-12-16T23:18:00.003+07:002009-12-16T23:36:11.887+07:00

Understanding what WiTricity technology is—transferring electric energy or power over distance without wires—is quite simple. Understanding how it works is a bit more involved, but it doesn’t require an engineering degree. We’ll start with the basics of electricity and magnetism, and work our way up to the WiTricity technology.Electricity: The flow of electrons (current) through a conductor (like

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-5020430310669426272009-12-02T23:47:00.003+07:002009-12-02T23:52:32.380+07:00

A direct current flows constantly and uniformly throughout the cross-section of a uniform wire. An alternating current of any frequency is forced away from the wire's center, toward its outer surface. This is because the acceleration of an electric charge in an alternating current produces waves of electromagnetic radiation that cancel the propagation of electricity toward the center of materials

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-39673808873524474662009-12-02T23:37:00.004+07:002009-12-02T23:45:19.960+07:00

The line frequency (American English) or mains frequency (British English) is the frequency at which alternating current (AC) is transmitted from a power plant to the end user. In most parts of the world this is 50 Hz, although in the Americas it is typically 60 Hz. Precise details are shown in the list of countries with mains power plugs, voltages and frequencies.During the development of

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-59024255504716636732009-12-02T23:30:00.002+07:002009-12-02T23:37:03.761+07:00

Many different power frequencies were used in the 19th century. Very early isolated AC generating schemes used arbitrary frequencies based on convenience for steam engine, water turbine and electrical generator design. Frequencies between 16⅔ Hz and 133⅓ Hz were used on different systems. For example, the city of Coventry, England, in 1895 had a unique 87 Hz single-phase distribution system that

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-67346767432513019422009-12-02T15:17:00.005+07:002009-12-02T15:27:40.471+07:00

Harmonics Resonance is a phenomenon which can occur in a power system. It can cause system instability or damage to electrical components such as capacitors and transformers. Harmonic resonance occurs when the inductive reactance and the capacitive reactance of the power system become equal.However, as the order of the harmonics (frequency) increases, the inductive reactance increases while the

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-43863983232654864642009-12-02T14:46:00.005+07:002009-12-02T15:02:35.690+07:00

Three-phase AC induction motors are commonly used in industrial applications. This type of motor has three main parts, rotor, stator, and enclosure. The stator and rotor do the work, and the enclosure protects the stator and rotor.Stator Core The stator is the stationary part of the motor’s electromagnetic circuit. The stator core is made up of many thin metal sheets, called laminations.

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-11116053461888367602009-12-02T13:28:00.003+07:002009-12-02T13:35:16.284+07:00

AC motors are used worldwide in many applications to transform electrical energy into mechanical energy. There are many types of AC motors, but this course focuses on threephase AC induction motors, the most common type of motor used in industrial applications. An AC motor of this type may be part of a pump or fan or connected to some other form of mechanical equipment such as a winder, conveyor,

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-60900218485019434472009-12-02T08:00:00.000+07:002009-12-02T14:28:33.828+07:00

Before discussing AC motors it is necessary to understand some of the basic terminology associated with motor operation. Many of these terms are familiar to us in some other context. Later in the course we will see how these terms apply to AC motors.Force In simple terms, a force is a push or a pull. Force may be caused by electromagnetism, gravity, or a combination of physical means. Net Force

HaGehttp://www.blogger.com/profile/15838329806829677260noreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-9513453039955102642009-02-01T09:45:00.002+07:002009-02-01T10:11:26.131+07:00

Analysis of the AC power generation process and of the alternating current we use in almost every aspect of our lives is necessary to better understand how AC power is used in today’s technology.Effective ValuesThe output voltage of an AC generator can be expressed in two ways. One is graphically by use of a sine wave (Figure 1). The second way is algebraically by the equation e = Emax sin wt,

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-64691085363022402012009-02-01T09:37:00.003+07:002009-02-01T09:45:24.495+07:00

An understanding of how an AC generator develops an AC output will help us analyze the AC power generation process.The elementary AC generator (Figure 1) consists of a conductor, or loop of wire in a magnetic field that is produced by an electromagnet. The two ends of the loop are connected to slip rings, and they are in contact with two brushes. When the loop rotates it cuts magnetic lines of

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-26114529373844006262009-02-01T09:19:00.005+07:002009-02-01T09:35:59.934+07:00

Before operations with DC circuits can be studied, an understanding of the types of circuits and common circuit terminology associated with circuits is essential.Schematic DiagramSchematic diagrams are the standard means by which we communicate information in electrical and electronics circuits. On schematic diagrams, the component parts are represented by graphic symbols, some of which were

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-59759113878221801182009-02-01T09:08:00.004+07:002009-02-01T09:19:23.176+07:00

When most people think of DC, they usually think of batteries. In addition to batteries, however, there are other devices that produce DC which are frequently used in modern technology.BatteriesA battery consists of two or more chemical cells connected in series. The combination of materials within a battery is used for the purpose of converting chemical energy into electrical energy. To

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-83830411112398447742009-01-31T10:20:00.005+07:002009-01-31T12:41:51.347+07:00

What is a magnetic circuit? To better understand magnetic circuits, a basic understanding of the physical qualities of magnetic circuits will be necessary.A magnetic circuit can be compared with an electric current in which EMF, or voltage, produces a current flow. The ampere-turns (NI), or the magnetomotive force (Fm or mmf), will produce a magnetic flux phi(Figure 1). The mmf can be compared

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-9842192509405987062009-01-31T09:52:00.005+07:002009-01-31T17:38:40.882+07:00

Certain metals and metallic oxides have the ability to attract other metals. This property is called magnetism, and the materials which have this property are called magnets. Some magnets are found naturally while others must be manufactured.Magnetism is a result of electrons spinning on their own axis around the nucleus (Figure 1).Figure 1 Electron Spinning Around Nucleus Produces Magnetic

Dunia Listriknoreply@blogger.comtag:blogger.com,1999:blog-6907465750036234358.post-25906680239821592172009-01-31T09:29:00.003+07:002009-01-31T13:07:49.054+07:00

This article provides information on the following methods of producing electricity:• Electrochemistry• Static (friction)• Induction (magnetism)• Piezoelectric (pressure)• Thermal (heat)• Light• Thermionic emissionElectrochemistryChemicals can be combined with certain metals to cause a chemical reaction that will transfer electrons to produce electrical energy. This process works on the

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