How Loud Is a Wind Turbine

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Electrical Installation Guide 2015 - FREE Download Now

Designer, Consultant, Contractor, Panel builder, Facility manager, Student, teacher, Standardisation or certification experts. we all have to know and comply to electrical installation standards and regulations, in order to ensure the safety (and more and more the energy efficiency) of our customers' electrical installations.  These international standards, set by the IEC, are complex and keep evolving; as a result, we struggled to stay informed.

As an example, are you aware that the IEC 60364 "Low-voltage electrical installations" part 4-42 "Protection for safety - Protection against thermal effects" has been updated in 2014, and that in particular it now includes recommendations for arc fault protection?  - in premises with sleeping accommodations;  - in locations with risks of fire due to the nature of processed or stored materials  [...]  In a.c. circuits, the use of arc fault detection devices (AFDDs) in compliance with IEC 62606 will satisfy the above-mentioned recommendation."  The technology also evolves, which may impact the way we design installations: as an example, LED lighting is increasing its share very fast, and as you know the LED lamps electrical characteristics and behavior (at startup in particular) require special care to be taken when choosing the related control and protection devices. And there is nothing worse than a customer site where the lighting circuit breakers may trip, or where the contactors may face welding of contacts, requiring urgent and costly on-site intervention. Fortunately, experts in the field from Schneider Electric got together in order to update the Electrical Installation Guide (EIG), a free and complete guide about electrical installations and the related standards.  Edited since several dozen years, it is a reference work which helps you understand and comply to the IEC standards to be applied in 2015. Thanks to this free and simplified guide, you'll ensure the reliability of your commercial, industrial, or domestic electrical installations.  What's new or updated in 2015 edition of the Electrical Installation Guide?  An updated list of relevant IEC standards, new content about LED lighting, new content about Arc Fault Detection Devices (AFDD), some updated chapters about "connection to the MV utility distribution network" and "MV and LV architecture selection guide for buildings", and also some updated examples of Energy Management architectures.  The content of the Electrical Installation Guide (2015 version) is clear and practical; there's no other guide of that stature!  The paper version costs 60€ but we propose you to DOWNLOAD the EIG 2015 right NOW and FOR FREE by clicking on the button below:     DOWNLOAD GUIDE HERE

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How does a Transformer work ?

I will be uploading from now on material that I find explain electrical principles in the easiest understanding way so my readers find it all in just one place.

Hope you learn something once again.

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Buchholz Protection for Transformers

The Buchholz protection, protects the transformer again every abnormal phenomenon produce inside the tank. It bases in the fact that the irregularities in the transformer functioning cause heating in the winding and in consequence the production of gases from the oil, the quantity and speed of its production increases at the time the damage spreads. 

The gases that are produce inside the tank go up through the tube in which the relay is installed and they get trap in it.

Disposition of the relay is shown in the scheme 2. The relay box is filed with oil and it contains the floats a1 and a2. When ever little gas bubbles are produce, this elevate from the transformers tank to the oil tank and get trap in the relay, in it the level of oil drops progressively. The top float inclines and when the amount of gases is sufficient, it causes contacts c1 to close and activated the alarm circuit.

In the cases that no measure is taken given the alarm or given the failure the amount of gases is high, the second float drops closing a2 causing the main transformer circuit breaker to open. If a electrical arc is produce inside the transformer, a violent flow of gases will go to the oil tank and c2 to will close suddenly preventing important damage to the transformer.        

Over the top of the relay is a faucet b1, that allows gasses to scape. another faucet b2, allows to prove that the floats and contacts are in good shape.

The relay detects shorcircuits between windings, core and core - windings, phase interruption, excessive overload, oil leak etc. The great advantage of this relay is its high sensibility to warn deterioration or incipient faults, when the most sensibly protection systems wont be that effective.

The characteristic of the gases trp in the Buchholz relay can give an idea of the type of defect and where it produced. The most simple verification is the combustibility test of the gas.  In case of electric arc the oil decomposes producing acetylene that is flammable.

The color of the gases can give an idea of the nature of the defect.

• White: Paper destruction.
• Yellow: Wood destruction.
• Black or Grey: Oil decomposition.
• Red: Winding isolation damage.  

      A peephole allows to see the gases, the color have to be seen minutes apart from the moment of the event. 

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Why AC Power Systems have 3 phases?

I am kind of in a wondering phase right know, it all began with the frequencies and then... this next question WHY 3 PHASES. May be more than one electricity enthusiast that haven't got deep in to it but now is wondering. It is mostly mathematics the explanation, by increasing the number of phases the amount of power that is transmitted gets to a point that it is just not efficient, it gets to complex and expensive.

Lets hear this Senior Transmission Engineer for a moment,  he does why I like the most... get complex subjects explained in the most simple way possible.

       

Hope you learn something new once again. 

Any subjection for topics... leave it in the comment section.  

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Basic Principles Generators/Motors AC 2/2

Lets see now what this people have to say about AC machines.

Once again, hope you learn something new.

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Basic Principles Generators/Motors DC 1/2

Taking it back once more, back when I was at the university starting to know the electrical machines I have to be honest I had nightmares trying to acknowledge all the laws of physics that rule the way machines worked.

Today I just now thing, that the simpler the better so for those that just wanna know how it works and don't get to much over there heads here is a video that puts it just in simple words the way everyone likes it. Its an all video but I thing it is just great piece of work of explanation,

Hope you enjoy it and learn one or tow things.

If any suggestions for future post live it in the comment sections. Remember getting things explained in the easiest way is what I intend to do.

Watch the second part of this post: Basic Principles Generators/Motors AC 2/2

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Motor Selection Guide

When it comes to a Selection of an Electrical Motor for a set application some times engineers find themselves in a bast range of options and got confuse on which are the best "technically" for that option.

Once the engineers makes up their mind now they have to establish the rated characteristics to order the motor to the given manufacturer. Lets face it it is not that easy to remember all this parameters.

A few years ago when I was a fresh engineers coming out from the university I had a hard time selecting and ordering motors for a project I was involved in, and back then i found this Motor Selection Guide made by General Motor.

The guide basically describes all the characteristics that a motor has or could have if they are required and help you to properly choose and order the motor you really need. If by any chance you order a motor and its not the correct there comes the troubles so better take your time getting to know about types of motors is what I recommend.

So here is the link where you can find the guide I talk about. Hope you find it Useful.

DOWNLOAD MOTOR SELECTION GUIDE

 

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The origin of electrical frequencies – Why 50 or 60 Hz

A couple months ago I decided to emigrate from my home country Venezuela, to the southern country Chile. As an electrical engineer while I was looking for a job I spend some of my free time on studying the local electrical system, the first factor that I have to get used to is that here the system works at 50 Hz and most of the equipment are specify according to the IEC Standard. For the last 8 years I had worked on 60 Hz systems and using mostly ANSI Standard, it is not a BIG deal just have to get used to it.

While studying the electrical system and white all the spare time I started wondering, seriously, WHY? are there two frequencies and so close to each other, true be told never gave much thoughts to the subject always think of that like, its always been like that, obviously there is a story behind. While doing my research I found this article that explain very well the reasons. It was made originally on Spanish so it translate it as precise possible.    

The origin of electrical frequencies – Why 50 or 60 Hz 

Even when today it seems that there is always been a unique frequency for electrical power transportation, on each of the main zones of influence: 50 Hz for Europe and 60 Hz for EEUU, it haven't been like that. Will do a look back through the history of the frequencies that have been used.

In 1891, Westinghouse engineers, in Pittsburgh, took the final decision of considering 60 Hz as the frequency for the future, that same year, the engineers of Allgemeine Elektrizitats Gesellschaft (AEG)  choose 50 Hz.

Since those decisions were taken, those frequencies became the "frequencies for alternative current transmission" standard, in fact this decision keeps affecting us nowadays. The frequency generally depends on each country, one of the most peculiar cases is Japan, when a person travels from Tokio to Osaka have to keep in mind that has come from a 50 Hz to a 60 Hz zone.

With this little review will try to clarify the reasons why the engineers of Westinghouse and AEG didn't agree on an unique frequency and why they choose a different value.  

To know the background of the decisions that set the frequencies of our days we have to go back by the end of the XIX century, for that we need to go through the documents that allows us see the traces of these decisions and this will let us  chronologically review the facts that lead them.

Since early times the electric energy wasn't used as an amusement, it was used as a safe method to light the houses, the boulevards or as a method of energizing electrical motors in factories to produce mechanical movement that will allow us discard the expensive and little efficient mechanic transmission systems: through axis, belts, pulleys, and gears that were used in the industrial revolution Era. The used frequencies have changed from 40 and 53 Hz in Europe, and 133 + 1/3 and 125 Hz in EEUU to 50 and 60 Hz respectively. This article wont cover the transitions period from direct current, promoted by Edison and Kelvin and the alternative current (1887), whose defender was Nikola Tesla. That was a true war, technologically, economically and politically wise.
         

1866 - 1890

Even when it seems incredible in those days each manufacturer, Edison, Thomson - Houston, Westinghouse, Siemens, etc. generated, produced and distributed electrical energy, also they manufactured the motors and lamps that will work it. Where the electricity did not develop to the fullest as a conglomerate and it was attend to be used as individual items one from another, an important technological delay took place like in England, France or Spain.

As a clear example of this situation, in 1878, Edison Machine Works manufactured dynamos, Edison Tube Company manufactured conductors, Edison Lamp Works manufactured lamps and Electric Illuminating Company of New Yorl generated electricity in the Pearl Street Central.  
  

Focusing in AC, by 1884, Dr. Hopkinson demonstrated the possibility of the transmission of AC over short distances, while in that same year Gibbs and Gaulard presented the second version of their called 'Secondary Generator' precursor of the transformer, in the Turin exhibition. Tests were made of transmission from Turin to Lazio. The primary network was around 40 km long, 20 kW and 2.000 V.  In this period, Max Deri, Otto Blathy and Karl Zipernowsky, noticing the defects of Gibbs and Gaulard's machine, improve it closing the magnetic circuit. On September 16th of 1884 was finally completed the installation the transformer, called like that the first time, it characteristics were 120/72 V, 1.400 VA and 40 Hz.

In 1886, Westinghouse bought the transformer patents design by Gibbs-Gaulard and Max Deri, Otto Bláthy and Karl Zipernowsky and with the work of Stanley developed an ironclad transformer used in their Great Barrington exhibition, it was feed from an generator of the kind made by Siemens. It had poles, worked at 1.000 rpm therefore the 133+1/3 Hz.

f (p * n) / 120

Where:

f = frequency  en Hz

p = number of poles

n = spin speed in rpm

In change other manufacturers like Thomson-Houston Company used alternators of 15.000 cicles (p*n), that permitted a frequency of 125 Hz

For this reazon it began in EE.UU the "High Frequency Era" in the generation and transmission of electrical energy. Westinghouse 133 +1/3, Thomson y Houston 125 Hz y Fort Wayne Jenny Electric 140 Hz.

Really, in those years, the main use of electricity was lightning and either frequency perfectly fulfilled the requirements of quality, with lower frequencies the lamps would began to produce an annoying flashing effect.

1890 - 1925

This a period in the one appears an element that will annoy the relative tranquility of manufacturers, the induction motor.

The motors that were used for the development of mechanical power that moved the machines tools were couple directly, motor - machine toll, of the the machine worked at 80 rpm, it will required a 200 poles motor working ar 133 +1/3 Hz. This problem, the elevated pole number, wouldn't appear in Europe since there they used 40 Hz, therefore they required only 60 poles machines.

In 1890, AEG and Oerlikon used 40 Hz for their 175 km three-phase electrical line, from Frankfurt (receptors) to Laufen (production) using an alternator of 50 V phase tension, 32 poles with a spin speed of 150 rpm, that gives 40 Hz frequency. The transmission was made transforming in the origin from 50 to 8.500 V and in Frankfurt it was reduce to 65 V. Later they realize the stroboscopic problems, due the low frequency applied to the lamps and by 1891 they chose to used 50 Hz, that solve both problems. Generators design to feed the motors and lightning systems.



In 1890, the engineers form Westinghouse realize that working with frequencies above 130 Hz was preventing their induction motor development, to many poles in the machines stator. Analyzing the problem, came with the conclusion that 7.200 cicles (p*n), and therefore 60 Hz, was the optimum value for their motors and the coupling of the machines that were manufactured back them.

Steinmetz just before started working at Thomson-Houston Company determined the resonance problems, with the material that Hartford Electric adquied, was due the harmonics of the 125 Hz signal used to supply the energy. The way to solve this was reducing to 62,5 Hz. General Electric kept using 50 Hz that used its European partner AEG. In 1894, General Electric, realize that they where loosing sales in the AC market and drastically change to 60 Hz.

Is wasn't unanimity respect the 60 Hz, one of the biggest projects of the generation in the times, The Niagara Falls project, in 1892, to give electrical energy to Chicago chose a two-phase alternator of 12 poles, rotating at 250 rpm, that gives 25 Hz, Westinghouse was the company that develop the project. Like ways other manufacturers in those times build alternators of 8.000 cicles - 66 +2/3 Hz.

1925 - Actuality

Even when it seems like since 1921 every electrical system in EE.UU used 60 Hz, it wasn't like that. The transformation process to the standard frequency last until 1948. For example the Mili Creek Installations were not modified until the end of WWII.

 In England it was even worse since the Electric Light Act came up, where is was stated that every electrical material that were manufacture had to be able to be used for any person or compay, this prevent the transformer develop by Gibbs and Gaulard to be used in England (this was one of the reasons of their technological delay) this was different in EE.UU or Germany.

A extremely peculiar case is Japan. The Yokohama department sent to EE.UU. engineers so they can study the different technologies about the electricity in the moment, 1889. When they came back to Japan, they were convince of the pros of the "high frequency" and bought and installed an alternator from Stanley-Kelly-Chesney (SKC) that worked at 133 + 1/3 Hz, in Keage Canal. In 1895 sold an alternator of 50 Hz to a company in Tokyo.

Lets Remember that Stanley of SKC then change to General Electric, and was then that determined that 133 +1/3 was to high frequency for AC electrical motor, and changed the alternator production so they generated AC at 60 Hz. When a company of Osaka bought an alternator to AGE, this one manufactured them to generated at 60 Hz and there the frequency division in Japan began to the momment: East 50 Hz and West 60 Hz. 

Summary 

Truly, the determination of the most convenient frequency came from the necessity (like all technology existing) of over come the tech problems that were presenting while the electrical energy spread around the world.  

So, in the first years the electrical energy was used almost exclusively for public lightning, hotels, banks and houses of wealthy people and to avoid the stroboscopic effects high frequencies were used.  

When the electrical energy got into the fabrication process and the energy consume was designated no only to lightning, but also to power in motors the frequency was reduce to the the actual values.

The reason WHY 50 Hz in Europe and 60 HZ in EE.UU, came only and excusably determined for the position of  preponderance of AEG in Europe and GE in EE.UU, whose engineers at some point chose chose on of the actual frecuencies

"The winner sets and tells the history" 

Source: Articulo “El origen de los 50-60 Hz en la transmisión de la energía eléctrica”. Wrote by Eduardo Aznar Colino y Joaquín Royo García, and publish in Técnica Industrial 242 (Septiembre de 2001). Vía afinidadelectrica.com.ar

Translated by: Eg. Aaron Paradas

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