Electrical Power Distribution System

The main function of an electrical power distribution system is to provide power to individual consumer premises. Distribution of electric power to different consumers is done with much low voltage level. Distribution of electric power is done by distribution networks. Distribution networks consist of following main parts Distribution substation, Primary distribution feeder, Distribution Transformer, Distributors, Service mains. The transmitted electric power is stepped down is substations, for primary distribution purpose. Now these stepped down electric power is fed to the distribution transformer through primary distribution feeders. Over head primary distribution feeders are supported by mainly supporting iron pole (preferably rail pole). The conductors are strand aluminum conductors and they are mounted on the arms of the pole by means of pin insulators. Some times in congested places, underground cables may also be used for primary distribution purposes.

Distribution transformers are mainly 3 phase pole mounted type. The secondary of the transformer is connected to distributors. Different consumers are fed electric power by means of the service main. These service mains are tapped from different points of distributors. The distributors can also be re-categorized by distributors and sub distributors. Distributors are directly connected to the secondary of distribution transformers whereas sub distributors are tapped from distributors. Service main of the consumers may be either connected to distributors or sub distributors depending upon the position and agreement of consumers. In this discussion of electrical power distribution system, we have already mentioned about both feeders and distributors. Both feeder and distributor carry the electrical load, but they have one basic difference. Feeder feeds power from one point to another without being tapped from any intermediate point. As because there is no tapping point in between, the current at sending end is equal to that of receiving end of the conductor. The distributors are tapped at different points for feeding different consumers; and hence the current varies along their entire length.

Play Stunt Master

ONE-LINE DIAGRAM

In power engineering, a one-line diagram or single-line diagram (SLD) is a simplified notation for representing a three-phase power system. The one-line diagram has its largest application in power flow studies. Electrical elements such as circuit breakers, transformers, capacitors, bus bars, and conductors are shown by standardized schematic symbols.[1] Instead of representing each of three phases with a separate line or terminal, only one conductor is represented. It is a form of block diagram graphically depicting the paths for power flow between entities of the system. Elements on the diagram do not represent the physical size or location of the electrical equipment, but it is a common convention to organize the diagram with the same left-to-right, top-to-bottom sequence as the switchgear or other apparatus represented.

A linear induction motor (LIM) is an AC asynchronous linear motor that works by the same general principles as other induction motors but is very typically designed to directly produce motion in a straight line. Characteristically, linear induction motors have a finite length primary, which generates end-effects, whereas with a conventional induction motor the primary is arranged in an endless loop.

Linear motors frequently run on a 3 phase power supply. Their uses include magnetic levitation, linear propulsion, and linear actuators. They have also been used for pumping liquid metals.[1] Despite their name, not all linear induction motors produce linear motion, some linear induction motors are employed for generating rotations of large diameters where the use of a continuous primary would be very expensive.

TRANSDUCERS

A transducer is a device which converts a signal from one form to another. Most electronics circuits use both input and output transducers:

INPUT TRANSDUCERS-- Input Transducers convert a quantity to an electrical signal (voltage) or to resistance (which can be converted to voltage). Input transducers are also called sensors. Examples: LDR converts brightness (of light) to resistance. Thermistor converts temperature to resistance. Microphone converts sound to voltage. Variable resistor converts position (angle) to resistance.

OUTPUT TRANSDUCERS-- Output Transducers convert an electrical signal to another quantity. Examples: Lamp converts electricity to light. LED converts electricity to light. Loudspeaker converts electricity to sound. Motor converts electricity to motion. Heater converts electricity to heat.

SCOTT CONNECTION

*A Scott-T transformer (also called a Scott connection) is a type of circuit used to derive two-phase (2-φ) current from a three-phase (3-φ) source or vice-versa. The Scott connection evenly distributes a balanced load between the phases of the source.

*The Scott-T transformer connection may be also be used in a back to back T to T arrangement for a three-phase to 3 phase connection. This is a cost saving in the smaller kVA transformers due to the 2 coil T connected to a secondary 2 coil T in-lieu of the traditional three-coil primary to three-coil secondary transformer. In this arrangement the X0 Neutral tap is part way up on the secondary teaser transformer (see below). The voltage stability of this T to T arrangement as compared to the traditional 3 coil primary to three-coil secondary transformer is questioned.

*Nikola Tesla's original polyphase power system was based on simple to build two-phase components. However, as transmission distances increased, the more transmission line efficient three-phase system became more prominent. Both 2-φ and 3-φ components coexisted for a number of years and the Scott-T transformer connection allowed them to be interconnected.

*Assuming the desired voltage is the same on the two and three phase sides, the Scott-T transformer connection (shown below) consists of a center-tapped 1:1 ratio main transformer, T1, and an 86.6% (0.5√3) ratio teaser transformer, T2. The center-tapped side of T1 is connected between two of the phases on the three-phase side. Its center tap then connects to one end of the lower turn count side of T2, the other end connects to the remaining phase. The other side of the transformers then connect directly to the two pairs of a two-phase four-wire system.

Clock generator

A clock generator is a circuit that produces a timing signal (known as a clock signal and behaves as such) for use in synchronizing a circuit's operation. The signal can range from a simple symmetrical square wave to more complex arrangements. The basic parts that all clock generators share are a resonant circuit and an amplifier.
The resonant circuit is usually a quartz piezo-electric oscillator, although simpler tank circuits and even RC circuits may be used.
The amplifier circuit usually inverts the signal from the oscillator and feeds a portion back into the oscillator to maintain oscillation.
The generator may have additional sections to modify the basic signal. The 8088 for example, used a 2/3 duty cycle clock, which required the clock generator to incorporate logic to convert the 50/50 duty cycle which is typical of raw oscillators.
Other such optional sections include frequency divider or clock multiplier sections. Programmable clock generators allow the number used in the divider or multiplier to be changed, allowing any of a wide variety of output frequencies to be selected without modifying the hardware.
The clock generator in a motherboard is often changed by computer enthusiasts to control the speed of their CPU, FSB, GPU and RAM. Typically the programmable clock generator is set by the BIOS at boot time to the value selected by the enthusiast; although some systems have dynamic frequency scaling that frequently re-program the clock generator.