Faraday Cage demystified.

Hi folks.

Electricity is the lifeblood of many aspects of our world. Without volts and amps, many of our technological innovations would fail to exist. Even our bodies wouldn't function without an electrical charge zipping through our cells and neurons. But what electricity gives, electricity can take away. Although this form of energy is vital to so much of our lives, it's one of those things that are only good in the right amounts. Too much electricity can electrocute people. Likewise, it can kill our modern electronics and machines.

So what saves linemen working on 765 KV line? What saves us from the high energy radiations inside the microwave oven?

Thanks to Michael Faraday, the brilliant 19th-century scientist, and one of his namesake inventions, the Faraday cage, we humans have developed plenty of ways to control electricity and make it safer for our computers, cars and other inventions and for us, too. Faraday cages shield their contents from static electric fields. An electric field is a force field surrounding a charged particle, such as an electron or proton.

Electromagnetic radiation is all around us. It's in visible and ultraviolet light, in the microwaves that cook our food and even in the FM and AM radio waves that pump music through our radios. But sometimes, this radiation is undesirable and downright disruptive. That's where Faraday cages come in.

It is nothing but a net woven from metal wires and object kept inside is protected from the field present outside or vice versa (microwave ovens case). The gap between the wires should be less than the wavelength of the radiation to be blocked. As a Faraday cage distributes that charge or radiation around the cage's exterior, it cancels out electric charges or radiation within the cage's interior. In short, a Faraday cage is a hollow conductor, in which the charge remains on the external surface of the cage. It works best when grounded as it can direct all induced currents to ground.

A lot of buildings act as Faraday cages too, if only by accident. With their plaster or concrete walls strewn with metal rebar or wire mesh, they often cut down wireless Internet networks and cell phone signals (radio waves have wavelengths in few meters that is more than the distance between the iron strands).But the shielding effect most often benefits humankind. Microwave ovens reverse the effect, trapping waves within a cage and quickly cooking your food. Screened (faraday cage used as coating) TV cables help to maintain a crisp, clear image by reducing interference. (See for yourself in case you find a waste piece of one!)

Power utility linemen often wear specially made suits that exploit the Faraday cage concept. Within these suits, the linemen can work on high-voltage power lines with a much-reduced risk of electrocution.

Governments can protect vital telecommunications equipment from lightning strikes and other electromagnetic interference by building Faraday cages around them.  Also you'll find Faraday cages in the form of MRI (magnetic resonance scanning) rooms. MRI scans rely on powerful magnetic fields to create medically useful scans of the human body. MRI rooms must be shielded to prevent stray electromagnetic fields from affecting a patient's diagnostic images.

All modern armed forces depend on electronics for communications and weapons systems, but there's a catch --these systems are vulnerable to high EMPs (electromagnetic pulses). Electromagnetic bomb (E-bomb) is used to create these pulses and destroy the communication networks of the enemy. To safeguard critical systems, militaries sometimes use faraday cage shielded bunkers and vehicles.

We will talk more about making your own faraday cage and electromagnetic bomb in coming articles. Thank you for your time and please feel free to post about your areas of interest.

WAR OF CURRENTS: some history lessons for an electrical engineer...

Hi folks.

When you flip a switch and a lamp illuminates the room, you probably don't give much thought to how it works or to the people who made it all possible. If you were forced to thank the genius behind the lamp, you might name Thomas Alva Edison, the inventor of the incandescent light bulb. But just as influential perhaps more so was an incredible visionary named Nikola Tesla.

Tesla arrived in the United States in 1884, at the age of 28, and by 1887 had filed for a series of patents (7 patents in 3 years!) that described everything necessary to generate electricity using alternating current, or AC. To understand the significance of these inventions, you have to understand what the field of electrical generation was like at the end of the 19th century. It was a war of currents -- with Tesla acting as one general and Edison acting as the opposing general.

Edison unveiled his electric incandescent lamp to the public in January 1880. Soon thereafter, his newly devised power system was installed in the First District of New York City. When Edison flipped the switch during a public demonstration of the system in 1881, electric lights twinkled on and created demand for this brand-new technology. Although Edison's early installations called for underground wiring, demand was so great that parts of the city received their electricity on exposed wires hung from wooden crossbeams. By 1885, avoiding electrical hazards had become an everyday part of city life; so much so that Brooklyn named its baseball team the Dodgers because its residents commonly dodged shocks from electrically powered trolley tracks (really!).

Edison was a (extremely) staunch supporter of DC, but it had limitations. The biggest was the fact that DC was difficult to transmit economically over long distances. Edison knew that alternating current didn't have this limitation, yet he didn't think AC a feasible solution for commercial power systems. Elihu Thomson, one of the principals of Thomson-Houston and a competitor of Edison, believed otherwise. In 1885, Thomson sketched a basic AC system that relied on high-voltage transmission lines to carry power far from where it was generated. Thomson's sketch also indicated the need for a technology to step down the voltage at the point of use. Known as a transformer, this technology would not be fully developed for commercial use until Westinghouse Electric Company did so in 1886.

Even with the development of the transformer and several successful tests of AC power systems, there was an important missing link- How to use that transmitted power to get useful work? That link was the AC motor.

While Edison toiled to commercialize his electric lamp, Tesla worked through a problem that had intrigued him since he was a student at the Joanneum Polytechnic School in Graz, Austria. While a student there, Tesla saw a demonstration of a Gramme dynamo. A dynamo is a generator that uses a commutator - contacts mounted on the machine's shaft - to produce direct current instead of alternating current. Tesla mentioned to his instructor that it might be possible to do away with the commutator, which sparked horribly as the dynamo operated. This suggestion brought ridicule from his teacher, but it captured Tesla's imagination.

In 1881, Tesla had an inspired idea: What if one were to change the magnetic field in the stator of a dynamo instead of altering the magnetic poles of the rotor? This was a revolutionary concept that turned conventional concept on its head.

Let us see why it was so amazing. We all know for generation of EMF we need a conductor, magnetic field and relative motion. Before Tesla, all machines were working like stationary field and rotating conductor. Tesla was the first one to imagine rotating field and stationary conductors. This is highly impossible with DC currents. So Tesla started to search for currents that change direction.   In a traditional dynamo, the stationary stator provides a constant magnetic field, while a set of rotating windings the rotor turns within that field. Tesla saw that if this arrangement were reversed, the commutator could be eliminated.

Of course, bringing this idea to reality would take years of work. Tesla began in 1882 while employed at Continental Edison Company in Paris. During the day, he would install incandescent lighting systems based on Edison's DC power system. In his spare time, he would experiment with AC motor designs. This went on for two years, until Tesla transferred to the Edison Machine Works in New York City. By some accounts, Tesla described his ideas about AC to the famed American inventor, but Edison showed no interest. Instead, he had Tesla make improvements to existing DC generation plants. Tesla did so, only to be disappointed when Edison failed to pay him properly. Tesla quit, and the paths of the two men diverged permanently.

(After this, they both criticized each other publicly and when they received Nobel Prize, They refused to receive it together and the end result was no-one got Nobel Prize. Can you believe that?)

Tesla received financial backing from Charles Peck, an attorney, and Alfred S. Brown, a superintendent at Western Union. Peck and Brown helped Tesla establish a laboratory just a few blocks away from Edison's lab in Manhattan, and encouraged the young engineer to perfect his AC motor. Tesla did just that, building what would become known as a polyphase induction motor. The term polyphase refers to a motor based on multiple alternating currents, not just one. The term induction refers to the process whereby the rotating stator magnets induce current flow in the rotor. Tesla's original motor was a two-phase version that featured a stator with two pairs of magnets, one pair for each of two phases of AC.

In 1887, Tesla filed for seven U.S. patents describing a complete AC system based on his induction motor and including generators, transformers, transmission lines and lighting. A few months later, Tesla delivered a lecture about his revolutionary new system to the American Institute of Electrical Engineers. The lecture caused a sensation and, despite an anti-AC campaign initiated by Edison, convinced many experts that an AC power system was more than just feasible - it was far superior to DC.To bring a good idea to market, it takes some clout. In this case, the clout came from an inventor who made a fortune in the railroad industry.

George Westinghouse, whose own electric company was struggling to work out the details of a successful AC power system, heard about Tesla's 1888 lecture and immediately was intrigued. When Peck and Brown approached Westinghouse about commercializing Tesla's inventions, the entrepreneur responsible for the railroad air brake made a generous offer. He agreed to pay $25,000 in cash, as well as $50,000 in notes and a small royalty for each horsepower of electricity originating from the motor.

Westinghouse carried Tesla's inventions back to Pittsburgh, Penn., where he hoped to use the technology to power the city's streetcars. Tesla followed, and as an employee of the Westinghouse Electric Company, consulted on the implementation. The project didn't proceed smoothly, and Tesla frequently battled with Westinghouse engineers. Eventually, however, everyone pulled together to come up with just the right formula: an AC system based on three-phase, 60-cycle current. Today, almost all power companies in the United States and Canada supply 60-cycle current, which means the AC completes 60 changes of direction in one second. This is known as the frequency of the system.

By the early 1890s, Edison and the supporters of DC felt genuinely threatened. They continued to make claims that AC was dangerous and pointed to a disastrous electrocution attempt in 1890 as evidence. But they suffered a severe blow in 1893, when Westinghouse won the bid to illuminate the Chicago World's Fair. His competition was General Electric (GE), the company formed by the merger between Edison General Electric and Thomson-Houston. GE was the leading torchbearer for DC-based power (and still is one of the most awesome companies for us). Westinghouse won the bid on cost, but when President Grover Cleveland flipped a switch to light 100,000 incandescent lamps across the fairgrounds, very few doubted the superiority of AC power.

Westinghouse mollified many remaining doubters in 1895 by designing a hydroelectric plant at Niagara Falls that incorporated all of the advances made in AC. At first, the plant only supplied power to Buffalo, New York. But it wasn't long before power was being transmitted to New York City. (The generators still working have Tesla’s name inscribed in their name plate.)

 In fact, it can be said that Tesla's AC motor and poly-phase AC system won the war of currents because they form the basis of all modern power generation and distribution. However, direct current --Edison's baby --didn't disappear completely. It still operates automobile electrical systems, locomotives and some types of motors and long-distance transmission.

These were some history lessons you should know if you call yourself an electrical engineer. Do feel proud to carry on this legacy and thank you for your time. 

Transformers -1

Hi folks.
I think we didn't talk much about the heart of the power system itself - transformers.

The core of the transformer is a very important component of it and governs the operating character of the transformer.Let us talk something about the materials used for core. As we always say, It is not made up of silicon steel (popularly known as electrical steel). It is made up of something called- CRGO steel (Cold Rolled Grain Oriented Steel).

Well it is basically silicon steel but treated specially we can say. Addition of silicon to iron is important as it significantly increases the electrical resistivity of the steel, which decreases the induced eddy currents and narrows the hysteresis loop (area under B-H curve is proportional to the losses) of the material, thus lowering the core loss. However, the grain structure hardens and embrittles the metal, which adversely affects the workability of the material.
So this Si-steel has BCC structure - Body centered cubic structure (you can find this in some standard chemistry book or Google it). This crystal when subjected to magnetic fields can undergo magnetization in 3 ways (directions)-
1. Along the shorted edge of the cube
2. Along the face diagonal of the cube
3. Along the through diagonal of the cube

Studies show that shorter the length of axis of magnetization, lower is the reluctance offered. In the last articles, we have seen, to reduce magnetizing current permeability should be very high and that implies reluctance offered should be very low.
So we take special efforts to magnetize every crystal (almost) along the shortest axis that is the edge of the cube.  This texture is developed by a series of careful working and annealing operations. Annealing, in metallurgy and materials science, is a heat treatment that alters the physical and sometimes chemical properties of a material to increase its ductility and to make it more workable. It involves heating a material to above its critical temperature, maintaining a suitable temperature, and then cooling.

The question remains is why don't we use this superior materials for all the electrical machines such as induction machines or synchronous machines?
The reason is if we see the flow of flux in these machines, it is not unidirectional and uniform in sense like transformer. So the reluctance offered in one direction will reduce and other direction might increase and this will create a harmful imbalance.
If you are interested, search for amorphous core transformers that are still superior compared to these. 

Thank you for your time and please feel free to leave comments about your areas of interest. I will surely try to post about them.

Pacemakers demystified.

Hi folks.

I was showing my blog to a friend of mine and when she read this name, she said - what is this pacemaker? So lets talk something about that.

Let me also tell you the reason for including it in blogs name. It is the best example of how much electricity is close to you- inside you, It can not be seen and felt but we are people controlling it so precisely that life of the people is at stake. 

We're all born with a 'pacemaker'. It's called the sinoatrial node (SA node), a small area at the top of the right atrium (upper chamber) of the heart. The SA node automatically generates an electrical signal that causes the upper chambers of the heart to contract. This signal begins in the SA node and travels to the atrioventricular node (AV node, which is also the SA node's back-up). The AV node acts slows down the electrical signal as it moves on to the lower chambers of the heart, while the atria contracts. With each contraction blood is pumped through the body.

In some people, the heart's electrical system -- called the cardiac conduction system -- misfires. A pacemaker is often able to correct and regulate the problem.

Unfortunately, the AV node is a poor substitute for the SA node and is usually only able to cause about 40 heartbeats per minute. In this situation an implantable permanent pacemaker can make a world of difference.

A pacemaker is an electronic device used to prevent a heart from beating abnormally. It's a generator made up of a battery and computer circuitry housed in a metal casing. The casing is implanted under the skin in the upper chest or shoulder region. Pacemaker wires are threaded through the veins of the shoulder and guided into the heart with the help of X-rays. Once the wires are positioned in the heart they are hooked up to the generator.

The first permanent pacemaker implant happened in 1958. Today there are three basic types of pacemakers:

• Single-chamber pacemakers
• Dual-chamber pacemakers.
• Bi-ventricular pacemakers

There are two main types of pacemaker programming: demand and rate-responsive. A demand pacemaker is designed to sense when the heart needs assistance by measuring each heartbeat and firing when the heartbeat becomes too slow or misses a beat. Rate-responsive pacemakers adjust heart rates depending on the patient's level of activity. They measure the SA node rate but also breathing, blood temperature and other factors.

Today's permanent pacemakers last at least 6 to 10 years depending on how frequently the device has to work. Every time a pacemaker is triggered it drains its battery. Occasionally a temporary pacemaker is used, usually during a patient's recovery from a heart attack or during an emergency situation to immediately speed up a slow heart rate.

So I really hope you liked knowing about the pacemakers. How pacemakers were invented is also a nice story. Do search for it. Thank you for your time and please free to comment about your interests.

Interview questions explained-4

Hi folks.
A very famous and confusing question asked is-

what is the resistance of the ground- high or low and what is resistivity of the ground- high or low?

Answer = The resistance of the ground is very low and is of the order of 0.5 Ohms and less than 1 ohm. So resistance of the ground is very less. If we measure the resistivity of ground that highly depend on the type of soil, we find it in the order of 400-2000 OhmM. the conductors we use have resistivity in 10^-6 OhmM. The area of cross section of earth as conductor is the reason for very high resistivity and yet low resistance.

this low resistance help us to provide return path for fault currents and avoid the problems of arcing grounds. Thank you for your time and please feel free to leave comment.

Interview question explained-3

Hi folks.
Lets talk something about transformers. (if you don't think of Optimus prime or Auto-bots after listening to this word and instead imagine a pole mounted dump metal box with oil stains on it, You are a true electrical engineer).

Q 1) Magnetization current in the transformer is desirable or not?
Q 2) Why transformer makes noise while working?

Answer 1- If we think logically, transformer draws magnetizing current to magnetize the core or to produce flux in the core. We must have flux in the core to have transformer action. So the magnetizing current is desirable. But it is absolutely FALSE #logical thinking is not always right!
Lets us see why. The answer to the above question lies in the ideal transformer concept. Ideal transformer has infinite core permeability. It implies that it needs zero external efforts to set up flux in the core. In case of practical transformer, as permeability is finite, we need to put in some energy to align the dipoles and to produce flux. That extra energy we give in the form of magnetizing current. So ideally magnetizing current should be zero. Magnetizing current under saturation condition leads to high no load current and worst power factor. So even though flux in the core is desirable, Magnetizing current is not.

Answer 2- Magnetostriction. We all know that there is dipole alignment process going on inside core when we magnetize it or demagnetize it. When the core is magnetized, to accommodate for the aligned dipoles, it expands. Similarly, for demagnetization, due to reverse process, it contracts. So the core undergoes contraction and expansion twice in one cycle of supply frequency (draw a sine wave and you will get it). So we get 2 compression and rarefaction (of resultant sound wave) in the 1 cycle of supply voltage. For 50 Hz supply, we get 100 Hz as the frequency of noise and that falls in our audio range (20-20,000 Hz). So we hear noise, that is often called magnetic hum. To avoid this, the laminations in the core are tightly stacked.
For the electronic transformers the same noise is produced but as they work on very high frequency, We are unable to hear that.  

Interview question explained-2

Hi folks.
A very tricky interview question we are going to discuss now.
Q. Resistance of a conductor depends on the frequency of the supply. True or false?

As soon as we hear this, we say false. Why? because we don't find any angular frequncy term introduced in R which is there in Xc or Xl.
But the answer my friends is TRUE.
Let us see why.
 
Have you heard that the AC resistance of the conductor is more than its DC resistance?
The reason for this is Skin effect. As the frequency of the supply increases, the current surprisingly tends to flow in the skin instead of body of the conductor.This is due the flux linkages in the conductor due to AC current carried by itself. You can understand it something like, An straight conductor when carries AC has inductance even though it is not in the coil form as we always imagine. For 50 Hz the value of resistance is 1.6 times that of DC resistance. We take this 1.6 as an approximation constant to account for skin effect. So as the frequency increases, the tendency of current to flow through skin increases and the effective cross section of the conductor decreases. Effective cross section means the cross section of conductor through which current is actually flowing. (It will be ring like structure if you imagine it and current concentrated in the outer parts).
In the basic resistance formula, we find that Area of cross section is inversely proportional to resistance. So The resistance of conductor increases.

If this is so, Why do we take Resistance constant in Electrical circuit analysis or day to day life?
Answer to 1st Question is ECA is an ideal subject where we assume that F parameter has no effect on R and in day to day life we ignore the skin effect which enables us to say firmly- R IS INDEPENDENT OF FREQUENCY..!

Skin effect is the base of design of ACSR conductors that we see on distribution poles. It is  helpful there. As we know current is actually flowing in outer parts, We can use aluminum outside (high conductivity and low mechanical strength) and we use steel inside (low conductivity and high mechanical strength). As a result we get conductor that has good conductivity as well as mechanical strength at low cost.

So next time when you will keep resistance constant under changing frequency, just keep in mind that you are ignoring skin effect. Thank you for you time and please feel free to comment or mail me about your areas of interest. It will be my genuine pleasure to post about them.

Some standard books to refer

Hi folks.
We are always worried about what book to refer and what not to, as we find very large number of XYZ publications available in market.
Here are some standard book that must be used. Beyond these the sky is the limit but these are few that should form the conceptual base for further studies.

(REF- books are suggested by expert faculties at ACE Hyderabad)

• Network Theory : Engineering Circuit Analysis by Hayt & Kemmerly
  (may be one by Ravish Singh is good to start with)
• Analog Devices : Electronic Devices and Circuit Theory by Boylestad
• Digital Circuits : Digital logic Design by Morris Mano
  (Jain & Jain is also good)
• Control Systems : Control Systems by Nagrath & Gopal
  (Norman Nise would also work)
• Electrical Machines: Electrical Machinery by PS Bimbhra
  (Nagrath kothari is option B)
• Power Electronics : Power Electronics by UA Bakshi
  (may be PS Bhimbara if you can find in library)
• Power Systems: Power System Engineering by Nagrath & Kothari
• Signals and Systems: Signals and Systems by Oppenheim Wilsky       
• Engineering Mathematics: Advanced Engineering Mathematics by Kreyszig
• For Objective Problems: GATE for EE by RK Kanodia
  (objective questions by GK Publications and and by Handa is also good)
  
  For all the remaining subjects xerox is the best choice!
  thank you for your time.

Whimshurst influence generator

hi folks.
I am currently working on whimshurst influence generator as my HV engineering project. Its an awesome handy gadget that you too can build generating voltages of the order of few KVs. The voltages are high enough to cause breakdown of the air at NTP.

you can check out an MIT video and an another page explaining its working.

http://www.youtube.com/watch?v=Zilvl9tS0Og
http://www.coe.ufrj.br/~acmq/whyhow.html

I will surely give  a demo of that in coming club service after I am done with it. If you too are interested then lets build it together..!

 There are few precautions you need to take to handle this gadget. So I suggest you to go through that first. All in all, it is a very fascinating hobby project.
After all, You are not a true electrical engineer if you don't get to play with high voltages..!

Please check out the above link and also search for corona motor (a motor that works on atmospheric charge and guess what, you can drive it using your own whimshrust generator).

Thank you for your time. and please feel free to comment about any more gadget that you are aware about.

Importance of fundamentals

Courtesy : http://electrical-mentor.blogspot.in/p/blog-page_6.html

(it is a blog written by one of the faculties of ACE academy who did M. Tech. in power and control from IIT Kanpur)

Dear Students,
The intention in writing this article is, so many students are asking me in the following way:

“Is it compulsory to read standard text books for every subject to get <100 GATE rank? Otherwise these ACE material and online tests are enough to get that rank”

One thing I would like to say that fundamentals in any subject are like foundation for any building. I can consider these types of questions like “Is it strong foundation required to construct nice building”. Answer is obviously yes. If you construct your building without strong foundation, you cannot celebrate house warming ceremony and you cannot stay in that building.

Getting good rank without fundamentals is exactly similar situation. Getting good rank should not be goal, whatever the education you are having during your student life, it should give confidence to face all the challenges in your life. It can be professional life or personal life. You may feel boring these types of lectures when you are in student, but this is the fact. You will realize this as you are getting old from the student stage

Even in our power electronics also, out of all the components everyone is interested in fundamental component only as it is useful component. There will be no more counter argument for this statement

Until you prepare objective books and mugging up the formulas & bits, you cannot answer new questions and challenges, Always try to learn the procedure, concepts and the approach

For the corporate companies, what you are solving is not an important matter but how you are solving is important. What is the approach you are demonstrating is important and how differently you are reaching the solution will really make differentiation from others

Love the subject, Learn fundamentals and enjoy the life.

Induction machine-1

Hi folks.

Let us talk about most common misconception that we people have.  If I say, I have a 6 pole induction machine what does it mean?

1      I have a machine with 6 poles per phase and total no of poles after energizing the winding will be 6*3 phases = 18

2    I have 6 poles in total. So it must be 2 poles per phase and 2*3= 6 (total poles)

Well. Actually both the above answers are wrong.

When I say a 6 pole induction machines it by default means that there are 6 poles in the machine per phase. But the total no of poles in the machine is not 18. It is 6 only. 

When we excite the winding of this machine, we get 6 poles in the space around rotor symmetrically distributed in space. And they belong to different phases at different instant of time. So there are 6 poles in the space in total. But while stating the rating of the machine we state it as 6 poles ‘per phase’ only.

I know it’s a bit confusing but if you draw 3 winding at 120 degree spatially displaced and pass 3 phases then it is quite clear that the 2 poles are resultant of the individual magnetic field produced. The total no of poles is 2 per phase as we have already stated and one of the poles (that are rotating, say N) belongs to the phase carrying positive maximum and other pole (say S) is the resultant of the remaining two phases that are on half of the negative maximum.

Thank you for your time and please feel free to  leave comment about any doubts and suggestions.

Interview questions explained-1

Hi folks.
Today morning one of mine friends asked the the question he faced in accenture interviews. I felt like like sharing that with you. So here it comes.
Why the operating frequency of India is 50 and of USA it is 60?
So, As India was ruled by British people, We just followed the way they had it. So we are working on 50 Hz. Believe it or not, the reason for USA to have 60 Hz is vendetta. How if you ask them, USA people are like - "If their vehicles go by left side then ours will go by right side.( This is why We people need driving lessons in USA) If their frequency is 50 then our will be 60" That's it!
Japan is a country that works on both 50 and 60.
Now you can ask me why 50 or 60 only, and why not 30 or 40.
The reason my friend is  more related to mechanical engineering. Almost all of the electricity comes from coal fired, Gas fired or nuclear plants where we use steam turbines.
So the problem with these mechanical systems is they are not as efficient as our systems.
 ( no offense to any mechanical engineer reading) So They suggested us that our turbines, they operate optimally on speed range of 3000-3600 rpm. At such a high speed to counter with centrifugal force we need to reduce the diameter and so the no of poles on the rotor.
So if we put no of poles 2 and speed 3000 in the basic SM formula then we get 50 Hz as operating frequency. If we put 2 poles and 3500 then we get 60 Hz. That's why these 2 only.
Hydro generators have adjustable no of poles and speed range so they can cope up with both 50 and 60 systems.
This operating frequency has very huge impact on the design of the power system components. We will discuss it in coming posts.
Thank you for your time and please do comment about your areas of interest.

Everyday electrical engineering -1

Hi folks,
Lets start our discussion with the basics.
Have you ever wondered why the earthing pin in the 3 pin connector is having more thickness and is more in length compared to other two? just to waste material or just to make it look cool? obvio no..!
Everyone knows the basic reason for providing earthing. It is for operator safety. As per the basic formula for resistance if we increase area of cross section then resistance will decrease. So this will provide least resistance path for the leakage currents and we , the operators will be safe.
Lets talk about length now. When we are putting club in socket, the first pin to come in contact with metal inside socket is earthing pin. So before giving supply to the device we ensure that all the leakage charge is grounded. Did you get the reason for more length?
Now if you observe even closer, there is a groove in the earthing pin. Can anyone tell me the reason for that?
Thank you for your time and please do comment about your areas of interest.