Abdul Majeed Khan (late) عبرالمجیر خان

athveen se F.A., B.A. tak k bachay yahan tution parh saktay hain

This conversation took place between the Calipha, 'Uthman ibn 'Affan, and 'Abdullah ibn Mas'ud when he was on his death bed. May Allah be pleased with them both.

*Note* These are not all of the major sins.

[Source: Al-Kaba'ir of Imam Adh-Dhahabi]

The hybrid HVDC breaker

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ABB has successfully designed and developed a hybrid DC breaker after years of research, functional testing and simulation in the R&D laboratories. This breaker is a breakthrough that solves a technical challenge that has been unresolved for over a hundred years and was perhaps one the main influencers in the ‘war of currents‘ outcome. The ‘hybrid’ breaker combines mechanical and power electronics switching that enables it to interrupt power flows equivalent to the output of a nuclear power station within 5 milliseconds – that’s as fast as a honey bee takes per flap of its wing – and twice as fast as it takes Usain Bolt to react to the starter’s gun! But its not just about speed. The challenge was to do it ‘ultra-fast’ with minimal operational losses and this has been achieved by combining advanced ultrafast mechanical actuators with our inhouse semiconductor IGBT valve technologies or power electronics (watch video: Hybrid HVDC Breaker – How does it work).

In terms of significance, this breaker is a ‘game changer’. It removes a significant stumbling block in the development of HVDC transmission grids where planning can start now. These grids will enable interconnection and load balancing between HVDC power superhighways integrating renewables and transporting bulk power across long distances with minimal losses. DC grids will enable sharing of resources like lines and converter stations that provides reliability and redundancy in a power network in an economically viable manner with minimal losses. ABB’s new Hybrid HVDC breaker, in simple terms will enable the transmission system to maintain power flow even if there is a fault on one of the lines.

This is a major achievement for the global R&D team in ABB who have worked for years on the challenge and finally come up with a circuit breaker capable of blocking and breaking DC currents at thousands of amperes and several hundred thousands of volts - corresponding to the average power consumption of one million Europeans ! It amounts to stopping power capable of feeding a large city much faster than an eye blink ! This speed helps protect the DC transmission system and prevent power outages in new low loss compact power superhighways. The next step is to install the breaker in pilot installations.

HVDC transmission remains a technology of choice for bulk power transmission over long distances with minimum losses. HVDC lines also require less space and are capable of going underground or underwater. Voltage source converter based HVDC applications in embedded AC grids and for offshore connections have grown substantially, in line with quantum leaps in power ratings and significant loss reductions. ABB pioneered HVDC transmission nearly 60 years ago and accounts for half the world’s HVDC installed base. It is befitting that the company that commissioned the world’s first 800 kilovolt UHVDC systems, the longest overhead HVDC link to go into commercial operation, the world’s longest underwater and underground HVDC links now writes the next chapter in the history of this technology and marks an important milestone in the legacy of electrical engineering.

رکاوٹ
تفصیل یہاں حاصل کریں:http://www.zaviia.com/2012/11/blog-post_7.html

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