Mengenal Filter Harmonisa: Filter Pasif

Tulisan ini mungkin tidak banyak membantu para praktisi karena bersifat teoritis. Sedangkan untuk keperluan praktis aplikatif, biasanya telah disediakan penjelasan dalam data produk untuk pemilihan rating tegangan, arus, daya reaktif dll. Untuk itu, bagi yang ingin mendapatkan pengetahuan praktis, disarankan untuk membaca langsung data produk filter tersebut.  

Tulisan ini melanjutkan tulisan sebelumnya dengan judul: Harmonisa Pada Sistem Tenaga Listrik. Dalam penggunaan istilah, harmonisa kadang disebut juga dengan harmonik. Sehingga ada yang menuliskan 'arus harmonisa' dengan 'arus harmonik'. 

Seperti yang diketahui secara umum, arus harmonisa muncul akibat beban non linear. Untuk menghilangkan arus harmonisa maka biasa digunakan filter harmonisa. Filter harmonisa bisa tersusun dari rangkaian aktif maupun pasif. Sedangkan gabungan keduanya biasa disebut filter hybrid. Berdasarkan pemasangannya pada jala-jala, filter ini bisa dibedakan menjadi dua jenis: paralel dan seri. Tipe paralel bekerja dengan mengalirkan arus harmonisa. Sedangkan tipe seri bekerja dengan menghambat aliran arus harmonisa. 

Student projects in energy fields: speed booster for bike and ocean wave energy converter

For more than 150 years New York City's Cooper Union for the Advancement of Science and Art (more commonly called The Cooper Union) has finished its school years with an annual event  showcasing student projects in the areas of art, architecture and engineering. Of the more than 300 projects on display this year were several inventions designed and built by students demonstrating a firm grasp of what society will want and need from technology moving forward. Such inventions included a bicycle that features a flywheel, and wave energy converter.

The school awarded its Nicholas Stefano Prize for an outstanding mechanical engineering senior project to Maxwell von Stein for his flywheel bicycle. The bike  uses a spinning flywheel to recover energy lost during braking so it can be later reclaimed to boost speed. A flywheel can temporarily store the kinetic energy from the bicycle when the rider needs to slow down, according to von Stein. The energy stored in the flywheel can be used to bring the cyclist back up to cruising speed. In this way the cyclist recovers the energy normally lost during braking. In addition to increased energy efficiency, the flywheel-equipped bicycle is more fun to ride since the rider has the ability to boost speed, he adds.

Von Stein's invention features a 6.8-kilogram flywheel from an automobile engine mounted to a bicycle frame. The flywheel is driven through a continuously variable transmission in the rear wheel. During charge, the transmission is shifted to increase the ratio of flywheel speed to bike speed.  During boost, it's shifted to decrease the ratio of flywheel speed to bike speed. The rider can charge the flywheel when slowing or descending a hill and boost the bike when accelerating or climbing a hill. The flywheel increases maximum acceleration and nets 10 percent pedal energy savings during a ride where speeds are between 20 and 24 kilometers per hour.


The Harold S. Goldberg Award for technical leadership in engineering went to Charles Canepa for an ocean wave energy converter. Canepa, who also won the school's William C. and Esther Hoffman Beller Prize for civil engineering, worked with fellow Cooper Union engineering students Matias Garibalid, Daniel Nash and Jacob Presky to design their wave energy converter so that the flap pushed by the waves is kept orthogonal to the waves' forward direction. This way, maximum torque is constantly transmitted to the device's drive shaft and maximum power is captured.

Canepa and his team are one of many groups in academia and industry developing technology that can convert wave power into renewable energy to decrease the world's dependence on fossil fuels. For example, the U.S. Energy Department isfunding a project led by Ocean Power Technologies to use the company's buoys to capture wave energy off the coast of Oregon. Likewise, Edinburgh-based Pelamis Wave Power is working with Swedish utility Vattenfall to install Pelamis serpentine-like wave energy converters near Scotland's Shetland Islands to deliver power to 26,000 homes there.


Ref: http://www.scientificamerican.com/blog/post.cfm?id=a-bike-that-uses-its-brakes-for-a-s-2011-06-24&WT.mc_id=SA_facebook

Peralatan penyimpan energi berkapasitas besar dan penggunaannya

Peralatan penyimpan energi
Peralatan penyimpan energi yang paling popular di masyarakat adalah baterei. Kadang disebut juga dengan istilah aki(accu). Dua istilah ini sebenarnya mengacu pada pengertian yang sama, Namun banyak yang mempersepsikan baterei sebagai penyimpan energi berdaya kecil. Dalam aplikasinya biasa dipakai untuk peralatan elektronik rumah tangga seperti radio, remote control, dst. Sedangkan aki lebih sering dipersepsikan sebagai penyimpan energi lebih besar. Dalam aplikasinya biasa dipakai untuk aplikasi mobil, UPS dll. 
Lalu, adakah penyimpan energi berkapasitas besar? 

Istilah-istilah baru dalam bidang energi listrik

Dalam kurun sekitar satu dekade terakhir, istilah-istilah baru ini begitu populer. Istilah tersebut yaitu Alternative Energy, Renewable Energy, Distributed Generation dan Microgrid. Seringkali orang juga kesulitan membedakan istilah-istilah tersebut karena isu yang dibahas juga sama. Artikel ini mencoba untuk menguraikan makna istilah tersebut secara sederhana.