transformer and types

A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors — the transformer's coils. A varying current in the first or primary winding creates a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the "secondary" winding. This effect is called mutual induction.

If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (VS) is in proportion to the primary voltage (VP), and is given by the ratio of the number of turns in the secondary (NS) to the number of turns in the primary (NP) as follows:

Transformers come in a range of sizes from a thumbnail-sized coupling transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to interconnect portions of national power grids. All operate with the same basic principles, although the range of designs is wide. While new technologies have eliminated the need for transformers in some electronic circuits, transformers are still found in nearly all electronic devices designed for household ("mains") voltage. Transformers are essential for high voltage power transmission, which makes long distance transmission economically practical.

An autotransformer has only a single winding with two end terminals, plus a third at an intermediate tap point. The primary voltage is applied across two of the terminals, and the secondary voltage taken from one of these and the third terminal. The primary and secondary circuits therefore have a number of windings turns in common. Since the volts-per-turn is the same in both windings, each develops a voltage in proportion to its number of turns. An adjustable autotransformer is made by exposing part of the winding coils and making the secondary connection through a sliding brush, giving a variable turns ratio. Such a device is often referred to as a variac.


For three-phase supplies, a bank of three individual single-phase transformers can be used, or all three phases can be incorporated as a single three-phase transformer. In this case, the magnetic circuits are connected together, the core thus containing a three-phase flow of flux. A number of winding configurations are possible, giving rise to different attributes and phase shifts. One particular polyphase configuration is the zigzag transformer, used for grounding and in the suppression of harmonic currents.

the below are some other transformers.
Leakage transformers
Resonant transformers
Audio transformers
Instrument transformers
Voltage transformers
current transformer

FILAMENTS

• The first successful light bulb filaments were made of carbon (from carbonized paper or bamboo), later replaced with tungsten. improve the efficiency of the lamp, the filament usually consists of coils of fine wire, also known as a 'coiled coil.' For a 60-watt 120-volt lamp, the uncoiled length of the tungsten filament is usually 22.8 inches or 580 mm , and the filament diameter is 0.0018 inches (0.045 mm).

• The advantage of the coiled coil is that evaporation of the tungsten filament is at the rate of a tungsten cylinder having a diameter equal to that of the coiled coil. Due to the coils creating gaps, such a filament has a lower surface area than the perceived surface area of the filament, and so evaporation is reduced. If the filament is then run hotter to bring back evaporation to the same rate, the resulting filament is a more efficient light sou

• There are several different shapes of filament used in lamps, with differing characteristics. Manufacturers designate the types with codes such as C-6, CC-6, C-2V, CC-2V, C-8, CC-88, C-2F, CC-2F, C-Bar, C-Bar-6, C-8I, C-2R, CC-2R, and Axial.

Electrical filaments are also used in hot cathodes of fluorescent lamps and vacuum tubes as a source of electrons or in vacuum tubes to heat an electron-emitting electrode.

• Filaments is a library package that can be used to create architecture-independent parallel programs---that is, programs that are portable efficient across vastly different parallel machines. Filaments virtualizes the underlying machine in terms of the number of processors and the interconnection. This simplifies parallel program design in two ways. First, programs can be written (or generated) with the focus on the parallelism inherent in the application, not the architecture.

1. Outline of Glass bulb
2. Low pressure inert gas (argon, neon, nitrogen)
3. Tungsten filament
4. Contact wire (goes out of stem)
5. Contact wire (goes into stem)
6. Support wires
7. Stem (glass mount)
8. Contact wire (goes out of stem)
9. Cap (sleeve)
10 Insulation (vitrite)
11 Electrical contact

• Second, programs can be written that use familiar shared-variable communication. Furthermore, Filaments uses a carefully designed API along with machine-specific runtime libraries and preprocessing that allow programs to run unchanged on both shared- and distributed-memory machines. Most importantly, applications programmed in Filaments run efficiently, achieving a speedup of over 4 on 8 processors or nodes in almost all tests that have been performed.

HOW LIFE TOOK PLACE ON EARTH?

When the earth formed some 4.6 billion years ago, it was a lifeless, inhospitable place. A billion years later it was teeming with organisms resembling blue-green algae.

1. How did they get there?
2. How, in short, did life begin?

• This long-standing question continues to generate fascinating conjectures and ingenious experiments, many of which center on the possibility that the advent of self-replicating RNA was a critical milestone on the road to life.

• Before the mid-17th century, most people believed that God had created humankind and other higher organisms and that insects, frogs and other small creatures could arise spontaneously in mud or decaying matter. For the next two centuries, those ideas were subjected to increasingly severe criticism, and in the mid-19th century two important scientific advances set the stage for modern discussions of the origin of life.
  

• Repeated generation after generation, natural selection could thus lead to the evolution of complex organisms from simple ones. The theory therefore implied that all current life-forms could have evolved from a single, simple progenitor - an organism now referred to as life's last common ancestor. (This life-form is said to be "last" not "first" because it is the nearest shared ancestor of all contemporary organisms; more distant ancestors must have appeared earlier.)

by , P#@N!M@#E$#.

my dream world.

• Life on Earth has existed for about 3.7 billion years ago."

_ " And in the end, it's not the years in your life that count. It's the life in your years".
_ABRAHAM LINCOLN;

_ " True religion is real living; living with all one's soul, with all one's goodness and righteousness" .


_ " Only a life lived for others is a life worthwhile".
_ALBERT EINSTEIN;