Function of Line supports

 Function of Line supports:- The function of line supports is obviously to supports the conductors. Line supports must be capable of carrying the load due to insulators and conductors including the ice and wind loads on the conductors along with the wind load on the supports itself.The line supports are various type including;- 1. wood 2. steel 3. Reinforced concrete poles 4. steel tower.

The main requirements of the line supports are:- 

1. High mechanical strength to withstand the weight of conductors and wind load.

2. Light in weight without the loss of mechanical strength.

3. Cheaper in cost.

4. Low maintenance cost.

5. Longer life.

6. Good looking.

1.Wooden poles:- These supports are cheapest , easily,available, provide insulating properties and  are extensively used for the distribution purpose specially in rural electrification keeping the cost low.Their use is usually limited to pressures (22kv) and for short spans (upto 60 mtr) To prevent decay owing to snow and rain, the wooden poles are protected by an aluminium, Zinc,or cement cap at the top.

Normally the wooden pole lenths is 10 to 12 mtr .The main drawback of wooden supports are less mechanical strength, smaller life.

2. Steel Poles:- The steel pole are three type (a) tabular poles (b) rail poles (c) rolled steel joists. The tabular pole are  of cross-section,the rail poles are of the shape of track used for railways and rolled steel joists are of I cross-section. such poles possess greater mechanical strength  and permit to use longer spans (50-80 m)  but cost is higher.

The advantages of tabular poles are that these poles are lighter in weight and easy ti install.

3. RCC Poles:- Poles made of reinforced cement concrete (RCC) usually called the concrete poles are used for low voltage distribution lines upto 33kv.These poles are two types in shape. one type is of square cross-section from bottom to top .The other type has rectangular bottom and square top with rectangular holes in it

4. Lattice steel Tower:- The Lattice steel tower are used for transmission at 1kv and 33kv and broad-base, lattice-steel taower are mechanically stronger and have got longer life due to their robust construction long spans (300m and above) can be used and are much usefull for crossing fields,valleys, railways lines,river.

Natural sources of Energy.

 Natural sources of Energy:-  There are some following natural sources of energy of which may be converted into electrical energy.   

1. Water        2.Fuels       3. Nuclear Energy      4. sun

5. Wind         6. Biomass.

1. Water:-  The potential energy of water collected at higher level or the kinetic energy of water flowing at high velocity can be used to run the turbines.These turbines or prime-mover are known as hydraulic turbines. Generators are coupled to these prime -movers which convert mechanical energy into electrical energy.In this case capital cost is very high but running cost is very low as no fuel is used.The largest hydro-electric power station is built in south America on the river Parana. It has 18 turbines generating 12600 million watts (12600 MW). In India one of the major hydro -electric power project is Bhakra Nangal project. The dam is erected across the river Sutlej and a lake called Gobind sager is crected behind it. Bhakra power plant has two power houses.overall capacity is 1200MW.

2.Fuel:- The most common source of energy is fuel.In nature ,fuel is available in solid,liquid or gaseous.

(a) solid fuel :-The main solid fuel is coal,which is available in nature in a very huge quantity.By the combustion of coal in the boiler heat energy is produced which is utilized to produce steam.The steam is utilized to run the the steam turbines to which generator are coupled.The electrical energy is generted.

(b) Liquied fuel:- From petroleum bulk of oil fuels ranging from petrol to heavy oil are obtained from the refineries. The main liquid fuel is diesel.In this case,diesel oil is injected into the piston cylinder of a diesel engine,where combustion of oil takes place which developes mechanical energy.

(c) Gaseous fuels:- Natural gas, when available in abundance at site,is used to run the gas turbines or it is burnt to produced steam which is used to run the turbines.A generator is coupled to the turbines to generate electrical energy.

3. Nuclear Energy:- The heavy substance whose nucleus whose can be broken into fragment is called nuclear fuel. The only substance found in nature which fissions and is capable of propagating nuclear chain  reaction is uranium .By fission of nuclear ,binding energy is released in the form of heat energy.which is utilized for conversion of water into steam.steam is utilized to drive steam turbines.A generator is coupled to the turbines to generate electrical energy.

4. Sun:-  This is primary sources of energy . Sun radiates energy in the form of electro-magnetic waves, which includes heat ,light, and lot of ultra violet radiation. The solar plant converted sun light into  the electrical energy. 

5.Wind:-  wind pressure is developed due to heating and cooling of the atmosphere which generates convection currents. This wind pressure is utilised in wind mills to drive small generators. The energy generated by the generated is used to charge the bank of batteries for continuous use.power generation in this case is limited and depend upon the velocity of wind.

6. Biomass:-  Biomass contain chemical energy .It can be burnt to give energy. you might have seen people in village burning cowdung cakes as fuel. This is a crude method of using biomass. A better method is to convert biomass into a gas called biomass. Biogas is prepered in the biogas plant.In this case biomass is mixed with water and a slury is made.By the action of bacteria on the biomass ,biogas is produced which is stored in the tank.

comparison between various type of power station

 comparison between various type of power station :- 

Hydro-power plant:- 1.Capital cost is very high on account of heavy cost of erection of  dam and machinery.

2.No fuel is used its running cost is very low.

3.They can be started instantly

4.They require a large space for reservoir and construction of dam.

5.Very less maintenance is required.

6.They depend upon the rain fall and a long dry season may affect the power generation.

7. These plants are located at places where dams can be errected and huges quantity of water is collected at a sufficient head.

8. These power plant are located far away from load center therefore long transmission lines are required and hence cost of transmission and distribution is very high.

9. As no fuel is used,therefore cost of trans-potation of fuel is nil.

10.These plant are most simple and clean.

Steam power-plant:- 1.  Capital cost is low in comparison to that of hydro and nuclear power stations.

2. Running cost is low as compared to disesel power power station due to low cost of fuel.but more than hydro and nuclear power stations.

3. They require long time for starting.

4. They require smaller space in comparison  to that of hydro and nuclear power station but more than diesel power stations.

5. They need more maintenance as compared to diesel and hydro power plant.

6. coal- fuel is limited and coal mines may get exhaust.

7.These plants are located near  the load center having the facilities  such as supply of fuel ,water transportation facilities.

8. These plants are located near the load center.

9. Cost of transportation of fuel is very high.

10. These plants are not so simple and atmosphere is polluted by fumes and residues of pulverized fuel.

Diesel power plant:- 1. Capital cost is minimum.

2. Running cost is very high.

3. They can be started quickely.

4. They require very less space.

5.They need more maintenance as compared to other.

6.Diesel oil- fuel is not available in plenty.

7.These plants can be installed at any place,

8.Transmission and distribution cost almost nil.

9. These plants are simple and clean compared to steam power plants.

10. These plants are also less reliable due to non-availbility of fuel.

Nucleare power stations:- 1.Capital cost is very high.

2. Running cost is very low as compared to diesel power stations.

3. They require long time for starting.

4. They require smaller space than hydro electric power station.

5.They need much more maintenance than other power plants.

6.These plants are located near to load center.

7. Cost of  transportation of fuel is very low.

8. These plant is very complicated to operate and special care is taken to remove the radioactive.

What is Fuse – Symbols, Features, Types, Applications & Advantages

What is Fuse :- A fuse is an electrical safety device (a component) that removes electrical current from an electrical circuit when the current in the electrical circuit is too high. Almost all electrical/ electronic appliances and equipment utilize it some way or the other. This post will discuss what is a Fuse, why it is used, its symbols as per standards, features, various types, applications, advantages and disadvantages.

FUSE

Fuse is an electrical safety device (or component) used from the early days of electrical engineering. It protects the circuit from overload. It is also called as the ‘Sacrificial Device’ in the circuit. Its working principle is based on the heating effect of the current. A fuse is a length of wire that melts (breaks or blows) when the current through it is above a certain level – the fuse rating. The 'fuse rating' is the electrical current that will blow the fuse, for instance 3 amps, 10 amps or 13 amps.

A fuse is a current sensitive piece of wire – when the fuse is working the wire is not broken, when the fuse has ‘blown’ the wire breaks.

Current Rating:- This is the current carrying capacity of a fuse measured at normal conditions and temperature. Before adopting this technique, one must make sure that circuit components are able to withstand the overload of current before the fuse act its role.
With this whenever there is a sudden increase of current only the fuses will blow out. Make sure that the circuit’s current is 75% (generally) of your fuse’s current rating.

               Current _Circuit = 75% of Current Rating of Fuse

I²T Value of Fuse:- This is the amount of energy which is carried by fuse element when there is an electrical fault or some short circuit happens. It measures the heat energy(energy due to current flow) of fuse & it is generated when fuse has blown.

                                   I²T _Circuit = I²T _Device
Interrupting or Breaking Capacity:-  It is the maximum rating of current without harm interrupt by the fuse is known as breaking or interrupting capacity of the fuse.

                           Breaking capacity > maximum rated voltage

                          Breaking capacity <short ckt current

Types of Fuse:- There are wide variety of fuses available for variety of applications. The main types of fuses are categorized into two broad categories based on the type of circuits they are used in. They are:-

                      1. DC Fuses   2. AC Fuses

1.   DC Fuse:- AC and DC fuses can be differentiated by their size. Since DC has a constant value greater than zero volt (0v), there will be a chance of occurrence of an electric arc between the melted wires. As it is difficult to avoid, the electrodes are placed at larger distance compared to AC fuses. DC fuses have  larger in size. 

2. AC Fuse:- AC fuses are smaller in size. They oscillated 50-60 times in every second from minimum to maximum. So there is no chance of Arc between the melted wires. Hence they can be packed in small size.

AC Fuses are further categorized into two broad categories based on the amplitude of applied voltage. They are

        1.Low Voltage Fuses  2. High Voltage Fuses

2.1 Low Voltage Fuse:-

As the name suggests, these are the fuses that are used in low voltages. Some of the Low Voltage Fuses are listed below.

2.1.1 Rewireable Fuse:-

Rewireable fuses (also known as Kit-Kat fuses) are of Low voltage type fuses. They are mainly used in small scale industries and house wiring. It consists of 2 parts namely:

• Fuse Base: Contains in and out terminal. It is made up of porcelain.
• Fuselink Carrier: It holds the  main element and is made up of aluminium, copper or lead.
  

Fig. 5 – Rewireable (Kit-Kat) Fuse

The fuselink carrier can be easily removed from the base without any electric shock. When it blows out, we can easily remove the fuselink carrier and replace the wire.

2.1.2 Cartridge Fuse:-

Cartridge Fuses are also known as Totally Enclosed type Fuses. The fuselinks are enclosed in the glass container. By having this type of design, it helps to keep the electric arc inside the container when it blows out.

Fig. 6 – Cartridge Type Fuses

They are used in many electrical and electronics appliances. They not only protect the device but also prevents fire caused by overheating of the circuits. These type of fuses are used in both Low voltage and high voltage.
Cartridge fuses are further classified into following two types:

• ‘D’ Type Fuses
• Link Type Fuses

2.1.2.1 ‘D’ Type Fuse:-

Diazed type fuses are made of bottle shaped ceramic body with metal end caps. ‘These fuses are highly reliable. It consists of cartridge, base, adapter ring and a cap. The cartridge is fitted with a cap and inserted into the base using the adapter ring.

Fig. 7 – ‘D’ Type Fuses

2.1.2.2 Link Type Fuse:-

Link type fuses are also known as High Rupturing Cartridge (HRC) fuses. The current flows under normal condition through the element. The body is made up of porcelain and the chamber of main element is filled with silica sand.
If short circuit occurs then the high current flows through it for some amount of time. If the fault is cleared then it will not blow out. But if the high current continues to flow for longer duration then it blows out by melting the element.
There are 2 types of HRC fuses namely,

• Blade Type Fuses
• Bolted Type Fuses
  

Fig. 8 – Link Type, ‘D’ Type and Bolted Type Fuses

2.1.3 Switch Type Fuse:-

It encloses a metal switch and the fuse. These types of fuses are used in low and medium voltage levels.

2.2 High Voltage Fuse:-

As the name suggests, these are the fuses that are used in high voltages. Some of the High Voltage Fuses are listed below.

2.2.1 Liquid Type HRC Fuse:-

Liquid type HRC fuses are most commonly used in high voltage circuits. These types of fuses are mainly used for transformer protection and circuits which have more than 400A.

Fig. 10 – Liquid Type HRC Fuses

Liquid type HRC fuses are filled with carbon tetrachloride. When there is a short circuit, the current passes through the element which melts and break. The liquid used in the fuses extinguish the arc created by the short circuit.

2.2.2 Cartridge type HRC Fuse:-

These type of fuses are similar to low voltage fuses. It is in the shape of a ring for removing the corona effect. Two fuse elements are used in it which are placed parallel to each other. The elements are made up of tungsten metal due to high resistance property.

Fig. 11 – Cartridge Type HRC Fuses

2.2.3 Expulsion Type HRC Fuse:-

Expulsion type of fuses are used to protect transformers and feeders. It is designed for 11kv and limit is up to 250 MVA. The fuse element is placed inside the cylinder and the tops are linked to the equipment. These fuses have a cylinder designed with synthetic resin bond paper.

Fig. 12 – Expulsion Type HRC Fuses

Applications of a Fuse:-

The applications of Fuses include nearly all electrical/ electronic devices such as:

• Electrical wiring at home.
• Appliances like AC, Refrigerator, TV, Washing machine etc.
• Laptops.
• Mobile chargers.
• Automobiles (Cars, Trucks, Buses, etc).

Advantages of Fuses:-

The advantages of Fuses includes:

• Fuses are cheapest form of protection available.
• No maintenance is required.
• When compared to circuit breakers, fuses require less time to react when circuit breaks.
• They are used in LCD monitors, battery packs, etc.

Disadvantages of Fuses:-

The disadvantages of Fuses includes:

• Considerable time is lost due to rewiring the fuses after operation.
• The current time characteristics of fuses cannot be related with that of protected apparatus.

 

About

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Welcome to" Tech Electrical Master" Knowledge about Electrical Devices.

This blog is authored and maintained by a group of Engineers having vast experience in Electrical, Electronic,  Digital Technology.  You may contact them with your queries via an shivpalsain002@gmail.com

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What is Capacitor,its principle ,SI units

What is Capacitor:-  Capacitor is a electronic  device that stores electric charge.Two metal  plates ,separated by an insulator constitute a capacitor or condenser.The plates accumulate electric charge when connected to power source.The plates are made of a conductive materials like-aluminum, silver,tantalum etc.

Capacitor

How capacitor work:- A capacitor is made of two metallic plates, with a dielectric material in between the plates. When you apply a voltage over the plates,a capacitor works by storing energy electrostatically in an electric field.

Basic Configration

Principle of a capacitor:- A capacitor  works on the principle that the capacitance of  a conductor is brought near it.A capacitor has two plates separated by a distance having equal and opposite chares.

SI Units :-  SI units of capacitance is Farads.

                              C= Q/V

Capacitor in series:- When negative plates (-ve) of one capacitor connected with positive (+ve) plates of another capacitor then we can say that capacitor are connected in series.

                                 1/C =1/C1+1/C2+1/C3

       

Capacitor in parallel:-When one plate of each capacitor is connected to the  positive (+ve) terminal of the supply mains and the another  plate of  each capacitor to the negative (-ve) terminal.

                                         C=C1+C2+C3

                

                        

what is Resistor

A resistor is an electrical componenets that limits or regulates the electrical current in an electronics  circuit.we can say also that a resistor is an electrical components that limits the flow of electrical current.......
                       The resulating current is inversely proportional to the resistance. This is defined in ohm's law ,which states that the current(I) is equal to the voltage (V) divided by the resistance (R).
                                 
                                                                      I= V/R

If too little current is flow in component, it may not operate.If too much current is allowed through, it can damage the component.Therefore resistor play an important role in an electronic circuit.
Sevral type of resistor exist ,but most are made of carbon and an insulating matrial,such as ceramic.

NOTE:- Resistor are represented in circuit diagrams by jagged line.They are usually labeled R1,R2,R3 ect.

what is Transformer

A transformes is static devices which consists of two or more stationary electric circuits interlinkerd by a common magnetic circuit for the purpose of transforming electrical energy between them.

The transfer of energy from one circuit to another takes place without a change in frequency.In modren  electrical distrubution system, transformer are used  to boost voltages levels so as decrease line losses during transmission.