Category Archives: Electricals

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Electrical engineering blog (http://engineering.electrical-equipment.org/) is an experience launched by a group of enthusiast’s experts in the field of electrical and energy management(mainly according IEC standards). These passionate people want to share their current experience as well as their questions about the future within a blog in order to suggest reactions from others and to discover new concrete ideas. We believe that we can attract and involve the designers & the consultants whatever position they have : suppliers, customers, independent experts and institutions experts. Obviously it is an English speaking blog, so far we have many exchanges with Asia and Europe, all countries are more than welcome… The objective is the promotion of ideas, openness to all point of views; this is not a space to promote products and services. We started nearly 3 months ago and are proud to register a very important number of visits, (40,000 today) with many comments, some being of high quality. Today we have 9 categories of articles, including 5 in energy efficiency, a major topic for everybody but also 4 categories on more traditional issues such as electrical distribution, design software’s …. We also wish to bring teaching tips web (Web2.0) well known by young pro on the web and probably less known by some experienced people that will be the main contributors of this blog. We are open to trade links with other blogs, forums and sites under the condition they are of high quality and relevant. You can subscribe to the newsletter of the blog that is sent every month. To comment on an article, it is direct and easy without any priori validation. To post an article, simply contact (engineering@electrical-equipment.org) the moderator of the blog who is Francois B.

Lightning Protection


Copied from http://www.elec-toolbox.com/usefulinfo/lightprot.htm
Why You Need Lightning Protection:

Lightning protection systems have changed drastically since Benjamin Franklin first invented lighting rods in 1752. Today’s systems must protect modern appliances, electrical systems and building constructions – they have to keep up with tile changing requirements of modern technology.

Underwriters Laboratories Inc. (UL) keeps up with these changes. Our experience in the safety testing field has earned UL worldwide recognition and respect. jurisdictional authorities, government agencies, insurance representatives and consumers alike have looked for the UL Mark on products and systems for almost100 years. When you see the Mark, it means that the product or system on which it appears compares with UL’s internationally recognized Standards for Safety.

In the lighting protection field, UL has been serving home and building owners since 1908. Today, UL has a large number of trained lighting protection field representatives located throughout tile United States. UL inspects sites ranging from cow barns to missile silos, front golf Course shelters to high-rise building systems. In fact, some of the most famous buildings in the world are protected by UL Master Labeled lightning protection systems, including the White House, the Sears Tower and the Washington Monument.

The Need for Lightning Protection:

Lightning can strike anywhere on earth – event the North and South Poles! In any U.S. geographical location, lightning storms occur as few as five times or as many as 100 times per year (see Fig. 1). -The Northeast United States has the most violent thunderstorms in the country because of the area’s extremely high earth resistivity (see Fig. 2). High earth resistivity (the earth’s resistance to conduct current) increases the potential of a lightning strike. If struck, structures in these areas will generally sustain more damage when there is no lightning protection system present.

Each year, thousands of homes and other properties are damaged or destroyed by lightning. It accounts for more than a quarter billion dollars in property damage annually in the United States. Lightning is responsible for more deaths and property loss than tornadoes, hurricanes and floods combined, but of these violent forces of nature, lightning is the only one we call economically afford to protect ourselves against.

Some properties have a higher risk of lightning damage. When considering installation of a lightning protection system, you may want to assess this risk. A risk assessment guide for determining lightning loss for all types of structures can be found in Appendix I of the National Fire Protection Association’s Lightning Protection Code, NFPA 780. This guide takes into consideration the type of structure, type of construction, structure location, topography, occupancy, contents and lightning frequency. Information may be obtained from tile NFPA, I Batterymarch Park, Quincy, MA, 02269, (800) 344-3555.

How a Lightning Protection System Works:

Lightning is the visible discharge of static electricity within a cloud, between clouds, or between tile earth and a cloud. Scientists still do not fully understand what causes lightning, but most experts believe that different kinds of ice interact in a cloud. Updrafts in the clouds separate charges so that positive charges moves end up at the top of the cloud while negative flow to the bottom. When the negative charge moves down, a “pilot leader” forms. ‘This leader rushes toward the earth in 150-foot discrete steps, ionizing a path in the air. ‘The final breakdown generally occurs to a high object the major part of the lightning discharge current is then carried in the return stroke which flows along the ionized path.

A lighting protection system provides a means by which this discharge may enter or leave earth without passing through and damaging non-conducting parts of a structure, such as those made of wood, brick, tile of- concrete. A lightning protection system does not prevent lightning from striking; it provides a means for controlling it and preventing damage by providing a low resistance path for the discharge of lightning energy.

FIG. 3 Lightning protection system for a dwelling: 1) air terminals spaced 20 feet apart along ridges and within two feet of ridge ends; 2) down conductors; 3) minimum of two groundings at least 10-feet deep; 4) roof projections such as weather vanes connected to system; 5) air terminal located within two feet of outside corners of chimney; 6) dormers protected; 7) antenna mast connected to roof conductor:- 8) connect gutters or other grounded metals as required; 9) surge arrester installed at service panel to protect appliances; 10) transient voltage surge suppressors installed in receptacles to which computers and other electronic equipment are connected.

FIG. 4 Lightning protection system commercial/industrial installation 1) air terminals spaced 20 feet apart around the perimeter of the building; 2) down conductors; 3) ground rods at least 10-feet deep; 4) art handling units bonded to system (may be in need of air terminals mounted on unit); 5) air terminals mounted within two feet of outside corner; 6) mid-roof conductor and air terminals at maximum 50-foot spacing; 7) grounded metal bodies bonded into system; 8) surge arresters installed at main electrical panels; 9) transient voltage surge suppressors installed in receptacles to protect computers and other office equipment.

UL’s Role in Lightning Protection:

UL’s Master Label Program for lightning protection involves periodic factory testing and inspection of system Components, along with field inspection components of completed installations. The program requires that all installers comply with UL’s internationally recognized Standards for lightning protection components and systems. UL,’s field representatives countercheck compliance with these Standards.

As a home or building owner, you should make sure that your installed system complies with the UL requirements. Here’s how:

Make certain that your installer is listed by UL and that a Master Label application is submitted to UL for your installation.When You request a Master Label for your system, your installer will ask you to sign the owner’s statement on the Master Label application form. The fourth (yellow) copy of the application is for your records. This should be done before the installer submits the Master Label application to UL for issuance of the Label. Make sure you receive the Master Label from the installer and place it on the protected structure as requested.

Buildings that are changed structurally or provided with additions can be re-examined under UL’s Reconditioned Lightning Protection Program. Under this program, the entire system must comply with the current UL Standards.

How You Can Protect Your Building:

1. Install a UL Master Label Lightning Protection System that complies with current nationally recognized codes. Lightning protection systems consist of air terminals (lightning rods) and associated fittings connected by heavy cables to grounding equipment, providing a path for lightning current to travel safely to ground.

2. Install UL Listed surge arresters at your service and telephone equipment to prevent surges from entering the home or other buildings oil power or telephone lines. Surges are diverted to ground, and both wiring and appliances are protected.

3. Install UL Listed transient voltage surge suppressors in receptacles to whic
h computers and other electronic equipment are connected in order to limit the voltage to 11/2 times the normal (maximum for solid state devices).

4. Look for the UL Mark. Remember, your lightning protection system may be installed using UL,’s requirements, but the system is not a Master Label system unless installed by one of UL’s Listed installers and a Master Label has been sent to you. Always “Look for the Master Label” on your lightning protection installation.


Capacitor bank

Berawal dari rasa penasaran pada car audio temen. Ada capacitor gede yang terpasang. Katanya alat tersebut adalah capacitor bank. Sedangkan setahu saya capasitor bank adalah alat untuk memperbaiki cos phi pada arus AC. Saya mencari jawaban atas ketidaktahuan saya tersebut. (Wajar aja saya nggak tahu lha wong grobak saya audionya cuma mp3 player yang tersambung dengan speaker)

Capacitors bank pada car audio

Capacitors are used to store extra energy for the amplifier to draw on demand.

Capacitors are useful because they can reduce the voltage loss (small margin) on the other electrical components in the car. These large capacitors may not cure headlight and/or interior light dimming as this is a sign of too little amperage from the alternator. A capacitor is only good so far as the audio system isn’t trying to pull too much from the electrical system. A capacitor doesn’t provide more power, it’s designed to ‘stiffen’ the voltage to the amp, nothing else. If the current isn’t there, a cap won’t help. The alternator must have at least 20% more amperage power than the entire vehicle and sound system combined for a capacitor to be of benefit which is ironically the same requirements for an amp to be efficient. A rule of thumb is that 0.5 farad of capacitance is needed for every 500 watts of power in your audio system. A capacitor does not affect sound in any way. It is strictly for power conditioning.
Sumber : http://en.wikipedia.org/wiki/Car_audio#Capacitors

Well, my english is not good so mungkin inti sarinya kurang lebih adalah sebagai berikut.
Capacitor akan menyediakan energi pada saat audio menyedot energi yang besar misalnya pada saat sub woofer-nya jeduk-jeduk. Sehingga energi keseluruhan pada mobil yang di-supply oleh aki tidak drop. Sebagai mana kita ketahui bahwa capacitor berfungsi menyimpan energi.


Capacitor bank Rumah tangga

Quote
Fungsi capacitor itu memperbaiki Cos phi. Cos phi itu faktor daya, V.A.cos phi = Watt. Meteran listrik itu mengukur ENERGI (Watt hour), bukan mengukur DAYA/Power (VA)
Meteran listrik = kWh meter.
Tegangan (V) relatif konstan (220V) bila ditambah kapasitor, maka cos phi akan NAIK, karena fungsi kapasitor akan menaikkan faktor daya. Besar cos phi itu dari 0 s/d 1 Kalau cos phi naik, Daya tetap, Tegangan tetap, maka yang TURUN adalah ARUSnya. makanya ada fenomena, bila sebelum pakai kapasitor 3 unit AC ngga bisa hidup, sekarang pakai kapasitor, 3 AC bisa hidup, MCB utama tidak jatuh. Karena MCB itu MEMBATASI ARUS. (Arusnya sudah turun karena dipasang capacitor sehingga tidak MCB tidak jatuh, tetapi Cos phi nya naik, kWh nya Tetap) Jadi, yang di pajang di mall-mall dengan bahan demo lampu TL dan ampere meter itu benar secara teknis. saat dipasang Capacitor, arus di ampere meter TERLIHAT turun, karena Cos phi nya naik. Tapi kalau disitu ada dipasang kWh meter, jumlah energi yang diukur akan TETAP.

Kesimpulan nya : Capacitor BUKAN alat untuk menghemat ENERGI = kWH
Tetapi alat untuk menurunkan arus listrik yang mengalir, dengan cara memperbaiki faktor daya.
MALAH yang akan terjadi adalah, setelah dipasang kapasitor, JUSTRU tagihan listrik NAIK. ????
Karena seneng !
Wah ! Dipasang kapasitor bisa nyalain AC + kulkas + TV + lampu + dll, yang pada keadaan sebelumnya itu ngga bisa.
Akibatnya semakin banyak alat listrik yg dihidupkan secara bersamaan, TAGIHAN LISTRIK nya ?
/Quote
Sumber : http://www.mail-archive.com/asosiasi-warnet@yahoogroups.com/msg37284.html
Wah…. tulisan tentang capasitor bank diatas bagus banget sayang kagak tahu siapa yang nulis. :Redaksi

Untuk listrik industri, PLN akan memberikan denda jika Cos phi kurang dari 0.85(kalu tidak salah sih…). Kalau untuk industri hukumnya wajib. Untuk rumah tangga saya pernah baca (lupa baca dimana) PLN sudah memasang capasitor pada jaringan.