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Tuesday, September 9, 2014

RECLOSER ( PBO) DAN SECTIONALIZER (SSO)

1.  PENUTUP BALIK OTOMATIS (PBO)
PBO (Recloser) adalah PMT yang dilengkapi dengan peralatan control dan relai penutup balik.
1.1.  Relai Penutup Balik (Reclosing Relay)
Relai penutup balik adalah relai yang dapat mendeteksi arus gangguan dan memerintahkan PMT membuka (trip) dan menutup kembali.
1.2.  Fungsi Relai Penutup Balik / PBO
PBO dipasang pada SUTM yang sering mengalami gangguan hubung singkat fasa ke tanah yang bersifat temporer, berfungsi untuk:
·         Menormalkan kembali SUTM atau memperkecil pemadaman tetap akibat  gangguan  temporer.
·         Pengaman seksi dalam SUTM agar dapat membatasi / melokalisir daerah yang terganggu.
1.3.  Jenis Relai Penutup Balik
Berdasarkan type perintah reclosing ke PMT dapat dibedakan dalam 2 jenis reclosing relay, yaitu :
·         Single-shot Reclosing Relay
  • Relai hanya dapat memberikan perintah reclosing ke PMT satu kali dan baru dapat melakukan reclosing setelah blocking time terakhir.
  • Bila terjadi gangguan pada periode blocking time, PMT trip dan tidak bisa reclose lagi (lock – out ).  
  • ·         Multi Shot Reclosing Relay.
  • o   Relai ini dapat memberikan perintah reclosing ke PMT lebih dari satu kali. Dead time antar reclosing dapat diatur sama atau berbeda..
    o   Bila terjadi gangguan , relai OCR/GFR memberikan perintah trip ke PMT pada saat yang sama juga mengarjakan (mengenergize) Reclosing relay.
    o   Setelah dead time t 1 yang sangat pendek ( kurang dari 0,6 detik), relai memberi perintah reclose ke PMT .
    o   Jika gangguan masih ada , PMT akan trip kembali dan reclosing relai akan melakukan reclose yang kedua setelah dead time t 2 yang cukup lama (antara 15- 60 detik).
    o   Jika gangguan masih ada, maka PMT akan trip kembali dan reclosing relai akan melakukan reclose yang ke tiga setelah dead time t 3 .
    o   Bila gangguannya juga masih ada dalam periode blocking tB 3, maka PMT akan trip dan lock out.
    o   Penggunaan multi shot reclosing harus doisesuaikan dengan siklus kerja (duty cycle) dari PMT.
  • 1.4.  Sifat Relai Penutup Balik
    ·         Operasi cepat (fast tripping): untuk antisipasi  gangguan  temporer.
    ·         Operasi lambat (delayed tripping) : untuk koordinasi dengan pengaman di hilir.
    ·         Bila gangguan  telah hilang pada operasi cepat maka PBO akan reset kembali ke status awal. Bila muncul  gangguan setelah waktu reset, PBO mulai menghitung dari awal.
    ·         Repetitive : riset otomatis setelah recloser success.
    ·         Non repetitive : memerlukan  reset manual (bila terjadi gangguan permanen dan bila gangguan sudah dibebaskan).
    ·         PBO atau Recloser adalah relai arus lebih sehingga karakteristik PBO dan OCR adalah sama (lihat karakteristik OCR).

    2.    SAKLAR SEKSI OTOMATIS (SSO)
    2.1.  Pengertian dan Fungsi SSO
    ·   SSO atau Auto Seksionalizer adalah saklar yang dilengkapi dengan kontrol elektronik/ mekanik yang digunakan sebagai pengaman seksi Jaringan Tegangan Menengah.
    ·   SSO sebagai alat pemutus rangkaian/beban untuk memisah-misahkan saluran utama dalam beberapa seksi, agar pada keadaan gangguan permanen, luas daerah (jaringan) yang harus dibebaskan di sekitar lokasi gangguan sekecil mungkin.
    ·   Bila tidak ada PBO atau relai recloser di sisi sumber maka SSO tidak  berfungsi otomatis (sebagai saklar biasa).
    8.2.2.  Klasifikasi SSO
    ·         Penginderaan : berdasarkan tegangan (Automatic Vacuum Switch) atau dengan Arus (Sectionalizer).
    ·         Media Pemutus : Minyak, Vacum,  Gas SF6.
    ·         Kontrol : Hidraulik atau Elektronik
    ·         Phase : Fasa tunggal atau Fasa tiga
    2.3.  Prinsip Kerja SSO
    ·         SSO bekerjanya dokoordinasikan dengan pangaman  di sisi sumber (seperti relai recloser atau PBO) untuk mengisolir secara otomatis seksi  SUTM yang terganggu.
    ·         SSO pada pola ini membuka  pada saat rangkaian tidak ada tegangan tetapi dalam keadaan bertegangan harus mampu menutup rangkaian dalam keadaan hubung singkat.
    ·         SSO ini dapat juga dipakai untuk membuka dan menutup rangkaian berbeban. Saklar ini bekerja atas dasar penginderaan tegangan.
    ·         SSO dilengkapi dengan alat pengatur dan trafo tegangan sebagai sumber tenaga penggerak dan pengindera.
    ·         Prinsip kerja SSO dengan sensor tegangan dijelaskan pada AVS di bawah.
    2.4.     AUTOMATIC VACUUM SWITCH (AVS)
    Prinsip Kerja AVS
    ambar II.19 di bawah sebagai ilustrasi Sistem Distribusi yang terbagi dalam 3 seksi dengan pengaman penyulang sebuah PMT dan dua buah AVS.
     
    Gambar : Sistem Pengaman JTM dengan PMT dan AVS
    Prinsip operasi AVS :
    ·         Dalam hal terjadi gangguan pada seksi III maka PMT penyulang trip, tegangan hilang. Setelah T3, semua AVS trip.
    ·         PMT masuk kembali (reclose pertama), seksi I bertegangan.
    ·         Setelah T1 menerima tegangan, AVS1 masuk, seksi II bertegangan.
    ·         Setelah T2 menerima tegangan, AVS2 masuk, seksi III bertegangan.
    ·         Apabila gangguan masih ada maka PMT trip kembali, AVS1 dan AVS2 lepas setelah T3.
    ·         PMT reclose yang kedua. AVS1 masuk setelah T1 sedangkan AVS2 sudah lock-out (pada saat masuk pertama tetapi hanya merasakan tegangan sebentar atau lebih kecil dari T2).
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Friday, June 6, 2014

bank soal jteti

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sumber :http://ifitalkssomething.wordpress.com/2013/03/10/bank-soal-just-find-what-you-need/
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Monday, May 12, 2014

contoh autocad MEP 2011

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Monday, April 21, 2014

Ebook Gratis

Hai Sahabat blogger!!!
kali ini Saya memberikan informasi tentang Ebook Gratis yang bisa didownload oleh sahabat semuanya.
Siapapun yang lagi membutuhkan ebook-ebook dibawah ini ,Silahkan klik aja judul ebook nya!!!

1.  Eletromagnetic William Hayt Book sixth edition[2001]
2.  Renewable Energy
3. Ogata Control System Engineering 3th Edition
4.Ogata Control System Engineering 4th Edition
5. Ogata Control System Engineering 5th Edition
6.Teknologi Rekayasa Surya
7.Pengolahan Sinyal Digital dengan Pemrograman MATLab
8.Fisika untuk Sains dan Teknik jilid 2 [serway jeweet]
9.Mekanika Fluida
10.Termodinamika Teknik
11.Mekanika Klasik
12.Dinamika dan Mekanika untuk Perguruan Tinggi
13.Mekanika Fluida 1
14.Dasar-Dasar Getaran Mekanis
15.Panas dan Termodinamika
16.Essential MATLab [Brian D.Hahn]
17.Elementary Mathematical and Computa [C.G.Gibson]
18.Fundamental of Instrumentation [Dominique Placko]
19.Instrumentation and Application [John G. Webster]
20.Electronic Device and Circuit Theory seventh Edition [Robert L.Boylestad]
21.Finite element methods for electromagnetic [Stanley Humphries Jr.]
22.Digital Circuit Analysis and Design with an Introduction to CPLDs and FPGAs [Steven T.Karris]
23.Circuit Analysis with MATLab [Steven T.Karris]
24.  Textbook of Electrical Technology vol.1
25. Textbook of Electrical Technology vol.2
26. Amphibionic Build your own Reptilian Robot [Karl William]
27. Basic Circuit Analysis 2th edition 
28.C Programing for Microcontroller AVR , Joe Pardue & Smiley micros
29.C++ from the Ground up third edition Herbert Schildt
30.Calculus Varberg Purcell Rigdon 9 edition
31. Discrete Time Control System Katshuhik Ogata 
32. Electric Machinery Fundamental Chapman
33. Electromagnetism for Electronic Engineering
34. Electronic Circuit Analysis 2nd Editin Dr.K.Lal.Kishore 
36. Essential Electrodynamic 5th Edition Raymond Protheroe
37.  Essential Electrodynamic 5th Edition solution Raymond Protheroe 
38 General Chemistry 5th Edition James E.Brady
39.Mathematical Method for Physics a Concise Introduction
40. Practical Amplifier Diagram Jack Robin and Chaster
41. Process Industrial Instrument and Control Hand
42. Schaum Outline’s Programming with C 2nd Edition Byron Gottfried
43. Schaum Outline’s Mechanical Vibration 
44Theory and Problem of Trigonometry 3rd Edition Robert E.Moyer and Frank Ayres
45. Simple Program Design
46. Phisics With Answer
47. Numerical Method for Engieering Chapra Canale
48. C++ Programming Language
50. Pemograman C dan Implementasinya
51.The PIC Microcontroller Your Personal Introductory Course Third Edition
52.PICMicro Microcontroller Pocket References
53. Fundamental Of C Programming
54. Barnett Embedded C Programming and the ATMEL AVR
55. Thomas Calculus 11th edition
56. Solution Manual Thomas Calculus 11th edition 
57. M.R.Spiegel Vector Analysis Schaum series
58. Advanced Calculus and Analysis 
59. Advanced Engineering Mathematics 10th edition
60. 1000 solved Problem in Classical Physics 
61. Young and Freedman Solution Manual University of Physiscs 12 th Edition 
62. Classical Mechanics Golstein 
63. Solution Manual Classical Mechanics Golstein 
64. Fundamental of Physics 8 th

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Sunday, April 13, 2014

Rankine cycle

The Rankine cycle is a model that is used to predict the performance ofsteam engines. The Rankine cycle is an idealised thermodynamic cycle of aheat engine that converts heat into mechanical work. The heat is supplied externally to a closed loop, which usually uses water as the working fluid. The Rankine cycle, in the form of steam engines, generates about 90% of all electric power used throughout the world,including virtually all biomass, coal,solar thermal and nuclear power plants. It is named after William John Macquorn Rankine, a Scottish polymath and Glasgow University professor.

Description

The Rankine cycle closely describes the process by which steam-operated heat engines commonly
 found in thermal power generation plants generate power. The heat sources used in these power plants are usually nuclear fission or the combustion of fossil fuels such as coal, natural gas, and oil.
The efficiency of the Rankine cycle is limited by the high heat of vaporization of the working fluid. Also, unless the pressure and temperature reach super critical levels in the steam boiler, the temperature range the cycle can operate over is quite small: steam turbine entry temperatures are typically 565°C (the creep limit of stainless steel) and steam condenser temperatures are around 30°C. This gives a theoretical maximum Carnot efficiency for the steam turbine alone of about 63% compared with an actual overall thermal efficiency of up to 42% for a modern coal-fired power station. This low steam turbine entry temperature (compared to a gas turbine) is why the Rankine (steam) cycle is often used as a bottoming cycle to recover otherwise rejected heat in combined-cycle gas turbine power stations.
The working fluid in a Rankine cycle follows a closed loop and is reused constantly. The water vapor with condensed droplets often seen billowing from power stations is created by the cooling systems (not directly from the closed-loop Rankine power cycle) and represents the means for (low temperature) waste heat to exit the system, allowing for the addition of (higher temperature) heat that can then be converted to useful work (power). This 'exhaust' heat is represented by the "Qout" flowing out of the lower side of the cycle shown in the T/s diagram below. Cooling towers operate as large heat exchangers by absorbing the latent heat of vaporization of the working fluid and simultaneously evaporating cooling water to the atmosphere. While many substances could be used as the working fluid in the Rankine cycle, water is usually the fluid of choice due to its favorable properties, such as its non-toxic and unreactive chemistry, abundance, and low cost, as well as its thermodynamic properties. By condensing the working steam vapor to a liquid the pressure at the turbine outlet is lowered and the energy required by the feed pump consumes only 1% to 3% of the turbine output power and these factors contribute to a higher efficiency for the cycle. The benefit of this is offset by the low temperatures of steam admitted to the turbine(s). Gas turbines, for instance, have turbine entry temperatures approaching 1500°C. However, the thermal efficiencies of actual large steam power stations and large modern gas turbine stations are similar.

The four processes in the Rankine cycle


There are four processes in the Rankine cycle. These states are identified by numbers (in brown) in the above Ts diagram.
  • Process 1-2: The working fluid is pumped from low to high pressure. As the fluid is a liquid at this stage the pump requires little input energy.
  • Process 2-3: The high pressure liquid enters a boiler where it is heated at constant pressure by an external heat source to become a dry saturated vapour. The input energy required can be easily calculated using mollier diagram or h-s chartor enthalpy-entropy chart also known as steam tables.
  • Process 3-4: The dry saturated vapor expands through a turbine, generating power. This decreases the temperature and pressure of the vapour, and some condensation may occur. The output in this process can be easily calculated using the Enthalpy-entropy chart or the steam tables.
  • Process 4-1: The wet vapour then enters a condenser where it is condensed at a constant pressure to become asaturated liquid.
In an ideal Rankine cycle the pump and turbine would be isentropic, i.e., the pump and turbine would generate no entropy and hence maximize the net work output. Processes 1-2 and 3-4 would be represented by vertical lines on the T-S diagramand more closely resemble that of the Carnot cycle. The Rankine cycle shown here prevents the vapor ending up in the superheat region after the expansion in the turbine,  which reduces the energy removed by the condensers.

Variables
\dot{Q}Heat flow rate to or from the system (energy per unit time)
\dot{m}Mass flow rate (mass per unit time)
\dot{W}Mechanical power consumed by or provided to the system (energy per unit time)
\eta_{therm}Thermodynamic efficiency of the process (net power output per heat input, dimensionless)
\eta_{pump},\eta_{turb}Isentropic efficiency of the compression (feed pump) and expansion (turbine) processes, dimensionless
h_1, h_2, h_3, h_4The "specific enthalpies" at indicated points on the T-S diagram
h_{4s}The final "specific enthalpy" of the fluid if the turbine were isentropic
p_1, p_2The pressures before and after the compression process
Equation
In general, the efficiency of a simple Rankine cycle can be defined as:
\eta_{therm}=\frac{\dot{W}_{turbine}-\dot{W}_{pump}}{\dot{Q}_{in}} \approx \frac{\dot{W}_{turbine}}{\dot{Q}_{in}}.
Each of the next four equations[1] is easily derived from the energy and mass balance for a control volume. \eta_{therm} defines the thermodynamic efficiency of the cycle as the ratio of net power output to heat input. As the work required by the pump is often around 1% of the turbine work output, it can be simplified.
\frac{\dot{Q}_{in}}{\dot{m}}=h_3-h_2
\frac{\dot{Q}_{out}}{\dot{m}}=h_4-h_1
\frac{\dot{W}_{pump}}{\dot{m}}=h_2-h_1
\frac{\dot{W}_{turbine}}{\dot{m}}=h_3-h_4
When dealing with the efficiencies of the turbines and pumps, an adjustment to the work terms must be made.
\frac{\dot{W}_{pump}}{\dot{m}} = h_2 - h_1 \approx \frac{v_1 \Delta p}{\eta_{pump}} = \frac{v_1 ( p_2 - p_1 )}{\eta_{pump}}
\frac{\dot{W}_{turbine}}{\dot{m}} = h_3-h_4 \approx (h_3-h_4) \eta_{turbine}

Real Rankine cycle
In a real power plant cycle (the name 'Rankine' cycle is used only for the ideal cycle), the compression 
by the pump and the expansion in the turbine are not isentropic. In other words, these processes are non-reversible and entropy is increased during the two processes. This somewhat increases the powerrequired by the pump and decreases the power generated by the turbine.
In particular the efficiency of the steam turbine will be limited by water droplet formation. As the water condenses, water droplets hit the turbine blades at high speed causing pitting and erosion, gradually decreasing the life of turbine blades and efficiency of the turbine. The easiest way to overcome this problem is by superheating the steam. On the Ts diagram above, state 3 is above a two phase region of steam and water so after expansion the steam will be very wet. By superheating, state 3 will move to the right of the diagram and hence produce a drier steam after expansion.

Variation of the basic Rankine Cylce
The overall thermodynamic efficiency (of almost any cycle) can be increased by raising the average heat input temperature  \left( \bar{T}_\mathit{in} = \frac{\int_2^3 T\,ds}{Q_\mathit{in}} \right) of that cycle. Increasing the temperature of the steam into the superheat region is a simple way of doing this. There are also variations of the basic Rankine cycle which are designed to raise the thermal efficiency of the cycle in this way; two of these are described below.

Rankine cycle with reheat[edit]


Rankine cycle with reheat
The purpose of a reheating cycle is to remove the moisture carried by the steam at the final stages of the expansion process. In this variation, twoturbines work in series. The first accepts vapor from the boiler at high pressure. After the vapor has passed through the first turbine, it re-enters the boiler and is reheated before passing through a second, lower-pressure, turbine. The reheat temperatures are very close or equal to the inlet temperatures, whereas the optimum reheat pressure needed is only one fourth of the original boiler pressure. Among other advantages, this prevents the vapor from condensingduring its expansion and thereby damaging the turbine blades, and improves the efficiency of the cycle, given that more of the heat flow into the cycle occurs at higher temperature. The reheat cycle was first introduced in the 1920s, but was not operational for long due to technical difficulties. In the 1940s, it was reintroduced with the increasing manufacture of high-pressure boilers, and eventually double reheating was introduced in the 1950s. The idea behind double reheating is to increase the average temperature. It was observed that more than two stages of reheating are unnecessary, since the next stage increases the cycle efficiency only half as much as the preceding stage. Today, double reheating is commonly used in power plants that operate under supercritical pressure.

Regenerative Rankine cycle[edit]


Regenerative Rankine cycle
The regenerative Rankine cycle is so named because after emerging from the condenser (possibly as a subcooled liquid) the working fluid is heated by steamtapped from the hot portion of the cycle. On the diagram shown, the fluid at 2 is mixed with the fluid at 4 (both at the same pressure) to end up with the saturated liquid at 7. This is called "direct contact heating". The Regenerative Rankine cycle (with minor variants) is commonly used in real power stations.
Another variation is where bleed steam from between turbine stages is sent tofeedwater heaters to preheat the water on its way from the condenser to the boiler. These heaters do not mix the input steam and condensate, function as an ordinary tubular heat exchanger, and are named "closed feedwater heaters".
The regenerative features here effectively raise the nominal cycle heat input temperature, by reducing the addition of heat from the boiler/fuel source at the relatively low feedwater temperatures that would exist without regenerative feedwater heating. This improves the efficiency of the cycle, as more of the heat flow into the cycle occurs at higher temperature. This process ensures cycle economy.

Organic Rankine cycle

The organic Rankine cycle (ORC) uses an organic fluid such as n-pentane or toluene in place of water and steam. This allows use of lower-temperature heat sources, such as solar ponds, which typically operate at around 70–90 °C The efficiency of the cycle is much lower as a result of the lower temperature range, but this can be worthwhile because of the lower cost involved in gathering heat at this lower temperature. Alternatively, fluids can be used that have boiling points above water, and this may have thermodynamic benefits. See, for example, mercury vapour turbine.


The Rankine cycle does not restrict the working fluid in its definition, so the name “organic cycle” is simply a marketing concept and the cycle should not be regarded as a separate thermodynamic cycle.

Supercritical Rankine cycle

The Rankine cycle applied using a supercritical fluid combines the concepts of heat regeneration and supercritical Rankine cycle into a unified process called the Regenerative Supercritical Cycle (RGSC) cycle. It is optimised for temperature sources 125 - 450°C.



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