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Cara Kerja Generator Set

Generator adalah mesin yang dapat mengubah tenaga mekanis untuk menjadi tenaga listrik dengan melalui proses induksi elektromagnetik. Generator ini telah memperoleh energi mekanis dari prime mover. Generator arus bolak-balik (AC) telah dikenal dengan sebutan alternator. Generator ini diharapkan dapat mensuplai tenaga listrik pada saat terjadi gangguan, dimana suplai tersebut akan digunakan untuk beban prioritas.

Sedangkan genset (generator set) merupakan bagian dari generator. Genset juga merupakan suatu alat yang dapat mengubah energi mekanik menjadi energi listrik. Genset atau sistem generator penyaluran adalah suatu generator listrik yang telah terdiri dari panel, berenergi solar dan terdapat kincir angin yang telah ditempatkan pada suatu tempat. Genset juga dapat digunakan sebagai sistem cadangan listrik atau “off-grid” (sumber daya yang tergantung atas kebutuhan pemakai). Genset juga sering digunakan oleh rumah sakit dan industri yang mempercayakan sumber daya yang mantap, seperti halnya area pedesaan yang tidak ada akses untuk secara komersial menghasilkan listrik. Generator telah terpasang satu poros dengan motor diesel, yang biasanya dengan menggunakan generator sinkron (alternator) pada pembangkitan. Generator sinkron ini terdiri dari dua bagian utama yaitu: sistem medan magnet dan jangkar. Generator ini kapasitasnya besar, medan magnetnya berputar karena terletak pada rotor.

Konstruksi generator AC adalah sebagai berikut:

1. Rangka stator
Terbuat dari besi tuang, rangka stator juga merupakan rumah dari bagian-bagian generator yang lain.

2. Stator
Stator telah memiliki alur-alur sebagai tempat untuk meletakkan lilitan stator. Lilitan stator telah berfungsi sebagai tempat GGL induksi.

3. Rotor
Rotor adalah bagian yang berputar, pada bagian ini juga terdapat kutub-kutub magnet dengan lilitannya yang dialiri arus searah, melewati cincin geser dan sikat-sikat.

4. Cincin geser
Terbuat dari bahan kuningan atau tembaga yang yang dipasang pada poros dengan memakai bahan isolasi. Slip ring ini akan berputar bersama-sama dengan poros dan rotor.

5. Generator penguat
Generator penguat juga merupakan generator arus searah yang dipakai sebagai sumber arus.

Pada umumnya generator AC ini akan dibuat sedemikian rupa, sehingga lilitan tempat terjadinya GGL induksi tidak akan bergerak, sedangkan kutub-kutub akan menimbulkan medan magnet berputar. Generator itu disebut dengan generator berkutub dalam, dapat dilihat pada gambar berikut.

Keuntungan generator kutub dalam bahwa untuk dapat mengambil arus tidak dibutuhkan cincin geser dan sikat arang. Karena lilitan-lilitan tempat terjadinya GGL itu tidak akan berputar. Generator sinkron juga sangat cocok untuk mesin-mesin dengan tegangan tinggi danarus yang besar.

Secara umum kutub magnet generator sinkron dibedakan atas 2 yaitu :

1. Kutub magnet dengan bagian kutub yang menonjol (salient pole).
Konstruksi seperti ini akan digunakan untuk putaran rendah, dengan jumlah kutub yang banyak. Diameter rotornya besar dan berporos pendek.

2. Kutub magnet dengan bagian kutub yang tidak menonjol (non salient pole).
Konstruksi seperti ini digunakan untuk putaran tinggi (1500 rpm atau 3000 rpm), dengan jumlah kutub yang sedikit. Kira-kira 2/3 dari seluruh permukaan rotor dibuat alur-alur untuk tempat lilitan penguat. Yang 1/3 bagian lagi juga merupakan bagian yang utuh, yang berfungsi sebagai inti kutub.

MESIN DIESEL

Mesin diesel termasuk mesin dengan pembakaran dalam atau disebut dengan motor bakar ditinjau dari cara memperoleh energi termalnya. Untuk dapat membangkikan listrik sebuah mesin diesel menggunakan generator dengan sistem penggerak tenaga disel atauyang biasa dikenal dengan sebutan Genset (Generator Set).

Keuntungan pemakaian mesin diesel sebagai Prime Mover
- Design dan instalasi sederhana
- Auxilary equipment sederhana
- Waktu pembebanan relatif singkat
- Konsumsi bahan bakar relatif murah dan hemat

Kerugian pemakaian mesin diesel sebagai Prime Mover
- Berat mesin yang sangat berat karena harus dapat menahan getaran serta kompresi yang tinggi.
- Starting awal berat, karena kompresinya tinggi yaitu sekitar 200 bar.
- Semakin besar daya maka mesin diesel tersebut dimensinya akan semakin besar pula, hal tersebut telah menyebabkan kesulitan jika daya mesinnya sangat besar.

Ada 2 komponen utama dalam genset yaitu:
1. Prime mover atau pengerak mula, dalam hal ini mesin diesel/engine
2. Generator.

Cara Kerja Mesin Diesel
Prime mover juga merupakan peralatan yang telah mempunyai fungsi menghasilkan energi mekanis yang diperlukan untuk dapat memutar rotor generator. Pada mesin diesel/engine telah terjadi penyalaan sendiri, karena proses kerjanya telah berdasarkan udara murni yang telah dimampatkan di dalam silinder pada tekanan yang tinggi (± 30 arm), sehingga temperatur di dalam silinder naik. Dan pada saat itu bahan bakar disemprotkan dalam silinder yang bertemperatur dan bertekanan tinggi melebihi titik nyala bahan bakar sehingga akan menyala secara otomatis.

Pada mesin diesel penambahan panas atau energi senantiasa dilakukan pada tekanan yang konstan. Pada mesin diesel, piston melakukan 2 langkah pendek menuju kepala silinder pada setiap langkah daya.

1. Langkah ke atas yang pertama merupakan angkah pemasukan dan penghisapan, di sini udara dan bahan bakar masuk sedangkan poros engkol berputar ke bawah.

2. Langkah kedua merupakan langkah kompresi, poros engkol terus berputar dapat menyebabkan torak naik dan menekan bahan bakar sehingga terjadi pembakaran. Kedua proses ini (1 dan 2) juga termasuk proses pembakaran.

3. Langkah ketiga merupakan langkah ekspansi dan kerja, di sini kedua katup yaitu katup isap dan buang tertutup sedangkan poros engkol terus berputar dan menarik kembali torak ke bawah.

4. Langkah keempat merupakan langkah pembuangan, disini katup buang terbuka dan dapat menyebabkan gas akibat sisa pembakaran terbuang keluar. Gas dapat keluar karena padaproses keempat ini torak kembali bergerak naik keatas dan menyebabkan gas dapat keluar. Kedua proses terakhir ini (3 dan 4) juga termasuk proses pembuangan.

5. Setelah keempat proses tersebut, maka proses berikutnya akan mengulang kembali proses yang pertama, dimana udara dan bahan bakar masuk kembali.

Editor : Dian Sukmawati
Sumber : jualgenset.co.id

Over the last five years or so, it seemed there was little that Dean G. Skelos, the majority leader of the New York Senate, would not do for his son.

He pressed a powerful real estate executive to provide commissions to his son, a 32-year-old title insurance salesman, according to a federal criminal complaint. He helped get him a job at an environmental company and employed his influence to help the company get government work. He used his office to push natural gas drilling regulations that would have increased his son’s commissions.

He even tried to direct part of a $5.4 billion state budget windfall to fund government contracts that the company was seeking. And when the company was close to securing a storm-water contract from Nassau County, the senator, through an intermediary, pressured the company to pay his son more — or risk having the senator subvert the bid.

The criminal complaint, unsealed on Monday, lays out corruption charges against Senator Skelos and his son, Adam B. Skelos, the latest scandal to seize Albany, and potentially alter its power structure.

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The repeated and diverse efforts by Senator Skelos, a Long Island Republican, to use what prosecutors said was his political influence to find work, or at least income, for his son could send both men to federal prison. If they are convicted of all six charges against them, they face up to 20 years in prison for each of four of the six counts and up to 10 years for the remaining two.

Senator Kenneth P. LaValle, of Long Island, who serves as chairman of the Republican conference, emerged from a closed-door meeting Monday night to say that conference members agreed that Mr. Skelos should be benefited the “presumption of innocence,” and would stay in his leadership role.

“The leader has indicated he would like to remain as leader,” said Mr. LaValle, “and he has the support of the conference.” The case against Mr. Skelos and his son grew out of a broader inquiry into political corruption by the United States attorney for the Southern District of New York, Preet Bharara, that has already changed the face of the state capital. It is based in part, according to the six-count complaint, on conversations secretly recorded by one of two cooperating witnesses, and wiretaps on the cellphones of the senator and his son. Those recordings revealed that both men were concerned about electronic surveillance, and illustrated the son’s unsuccessful efforts to thwart it.

Adam Skelos took to using a “burner” phone, the complaint says, and told his father he wanted them to speak through a FaceTime video call in an apparent effort to avoid detection. They also used coded language at times.

At one point, Adam Skelos was recorded telling a Senate staff member of his frustration in not being able to speak openly to his father on the phone, noting that he could not “just send smoke signals or a little pigeon” carrying a message.

The 43-page complaint, sworn out by Paul M. Takla, a special agent for the Federal Bureau of Investigation, outlines a five-year scheme to “monetize” the senator’s official position; it also lays bare the extent to which a father sought to use his position to help his son.

The charges accuse the two men of extorting payments through a real estate developer, Glenwood Management, based on Long Island, and the environmental company, AbTech Industries, in Scottsdale, Ariz., with the expectation that the money paid to Adam Skelos — nearly $220,000 in total — would influence his father’s actions.

Glenwood, one of the state’s most prolific campaign donors, had ties to AbTech through investments in the environmental firm’s parent company by Glenwood’s founding family and a senior executive.

The accusations in the complaint portray Senator Skelos as a man who, when it came to his son, was not shy about twisting arms, even in situations that might give other arm-twisters pause.

Seeking to help his son, Senator Skelos turned to the executive at Glenwood, which develops rental apartments in New York City and has much at stake when it comes to real estate legislation in Albany. The senator urged him to direct business to his son, who sold title insurance.

After much prodding, the executive, Charles C. Dorego, engineered a $20,000 payment to Adam Skelos from a title insurance company even though he did no work for the money. But far more lucrative was a consultant position that Mr. Dorego arranged for Adam Skelos at AbTech, which seeks government contracts to treat storm water. (Mr. Dorego is not identified by name in the complaint, but referred to only as CW-1, for Cooperating Witness 1.)

Senator Skelos appeared to take an active interest in his son’s new line of work. Adam Skelos sent him several drafts of his consulting agreement with AbTech, the complaint says, as well as the final deal that was struck.

“Mazel tov,” his father replied.

Senator Skelos sent relevant news articles to his son, including one about a sewage leak near Albany. When AbTech wanted to seek government contracts after Hurricane Sandy, the senator got on a conference call with his son and an AbTech executive, Bjornulf White, and offered advice. (Like Mr. Dorego, Mr. White is not named in the complaint, but referred to as CW-2.)

The assistance paid off: With the senator’s help, AbTech secured a contract worth up to $12 million from Nassau County, a big break for a struggling small business.

But the money was slow to materialize. The senator expressed impatience with county officials.

Adam Skelos, in a phone call with Mr. White in late December, suggested that his father would seek to punish the county. “I tell you this, the state is not going to do a [expletive] thing for the county,” he said.

Three days later, Senator Skelos pressed his case with the Nassau County executive, Edward P. Mangano, a fellow Republican. “Somebody feels like they’re just getting jerked around the last two years,” the senator said, referring to his son in what the complaint described as “coded language.”

The next day, the senator pursued the matter, as he and Mr. Mangano attended a wake for a slain New York City police officer. Senator Skelos then reassured his son, who called him while he was still at the wake. “All claims that are in will be taken care of,” the senator said.

AbTech’s fortunes appeared to weigh on his son. At one point in January, Adam Skelos told his father that if the company did not succeed, he would “lose the ability to pay for things.”

Making matters worse, in recent months, Senator Skelos and his son appeared to grow wary about who was watching them. In addition to making calls on the burner phone, Adam Skelos said he used the FaceTime video calling “because that doesn’t show up on the phone bill,” as he told Mr. White.

In late February, Adam Skelos arranged a pair of meetings between Mr. White and state senators; AbTech needed to win state legislation that would allow its contract to move beyond its initial stages. But Senator Skelos deemed the plan too risky and caused one of the meetings to be canceled.

In another recorded call, Adam Skelos, promising to be “very, very vague” on the phone, urged his father to allow the meeting. The senator offered a warning. “Right now we are in dangerous times, Adam,” he told him.

A month later, in another phone call that was recorded by the authorities, Adam Skelos complained that his father could not give him “real advice” about AbTech while the two men were speaking over the telephone.

“You can’t talk normally,” he told his father, “because it’s like [expletive] Preet Bharara is listening to every [expletive] phone call. It’s just [expletive] frustrating.”

“It is,” his father agreed.