Lockerz is a great site ,that allows you to collect PTZ(points) that are redeemable for free gifts and gift cards.Gifts in the site include ipods,iphones,PSP's,paypal and amazon gift cards,and many many more cool items.
All you have to do is to collect points(PTZ),you get PTZ for daily logging into the site and answering a daily question.You get 2 PTZ for each activity and if you become a Z-Lister ,you get 4 PTZ each.For becoming Z-Lister you must get 20 referrals.
So,are you interested in joining the site,if yes please your email id in comments or mail me your id to shvtrix@gmail.com so that i can send you invitation to join the site.(To become a member of lockerz you need to get invited by existing lockerz member).
Please read FAQs of Lockerz for more information.
Lets enjoy and get free gifts.
Monday, February 15, 2010
LOCKERZ-GET FREE GIFTS
Monday, July 27, 2009
PTC
one can join these sites and earn money,just click on the below banners or images and follow the necessary steps on the sites.Make sure to read terms and conditions.
NEOBUX
For free members the site pays
Per click: $0.010 (standard exposure) · $0.015 (extended exposure)
Per referral click: $0.005 (standard exposure) · $0.010 (extended exposure)
The minimum payout amount is set at $2.00 (two US dollars) for first payout request.
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XPANGO.COM: win ipods,PlayStations,gaming consoles,mobiles by completing simple offers and referrals ,claimed to b a genuine site
MYLOT:earn money for discussions on any topic.
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RUPEE MAIL
This site also pays Rs2.00 per referal.
bigmoneyptc
This site pays
$1 for every link you click and $10 for every site you join through BigMoneyPTC. In addition to that, we will also pay you 50% of your referrals' earnings!
CLIXSENSE
BUKSIA:Earn money for writing articles,sharing videos,audios,slides
Friday, February 20, 2009
JOBS
Company:Indian Space Research Organization [ISRO]
Openings:For electronic,mechanical,computer science engineers as scientist/engineer.
Eligibility:BE/B.Tech or equivalent in First Class with an aggregate minimum of 65% (average of all semesters for which results are available). Candidates who are slated to complete the BE/B.Tech course in the academic year 2008-09 are also eligible to apply provided final Degree in first class with 65% aggregate is available by 31.8.2009.
How to apply:Apply online in the ISRO web-site between 10-02-2009 and 12-03-2009.
Application Fees:Application Fee is Rs.100/- (Rupees One Hundred Only) for each application.Scheduled Castes (SC), Scheduled Tribes (ST) and Persons with Disabilities (PWD) candidates are exempted from Application Fee. Demand Draft details need to be filled-in at the time of on-line registration. The candidate before filing his/her application has to take a DD for Rs.100/- from any of the Nationalized Bank in favour of the Sr. Accounts Officer, ISRO HQ, Bangalore, payable at Bangalore.
The Applicant should enter the DD Number, date and name of the Bank in the space provided for the same in the web application. After filing the application, on-line, the applicant has to send the DD with his/her Full Name (as entered in web), Post Number and Registration No. written on the reverse of the DD to Administrative Officer (ICRB), ISRO Headquarters, Antariksh Bhavan, New BEL Road, Bangalore - 560231 by ordinary post superscribing on the envelope "ISRO RECRUITMENT-SCI/ENGR-SC(BE/B.TECH)".
IMPORTANT DATES:
For online submission:10-02-2009 to 12-03-2009.
For submission of hard copy(print out) of application and DD through post:19-03-2009.
Website:For further details visit ISRO job opportunities at:
http://www.isac.gov.in/advt.jsp/CentralBE (for above job opening)
http://www.isro.org/joboppor.htm (for all ISRO job openings)
Thursday, February 12, 2009
Synchronous Machines
Q.What is pull in torque?
A.A synchronous motor is non self starting therefore its rotor is excited till it picks up speed close to synchronous speed of stator rotating field.
This torque required by rotor to reach near synchronous speed is called Pull-In torque.
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Q.What is pull out torque?
A.Maximum torque a synchronous motor develops before running out of synchronous operation is called Pull-Out torque.
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Q.What happens to speed in synchronous motor on increase in load?
A.Unlike dc motors speed of a synchronous motor does not fall on application of load ,but the rotor tends to fall back in phase .
As the motor overloads the phase difference increases and finally magnetic interlock of stator and rotor breaks and the motor stops.
This phase difference angle is called load angle or coupling angle.
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Q.How does excitation effect a synchronous motor?
A.If over excited motor operates at leading power factor and if under excited at lagging
power factor.
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Q.What is a Synchronous Capacitor?
A.A over excited synchronous motor with no load is called a synchronous capacitor because
it operates at leading p.f under these conditions and hence acts like a capacitor.Under
these conditions a synchronous motor can be used for power factor improvement (reactive
power compensation)
FACTS
FACTS (Flexible AC Transmission Systems)
Basically this is the ac system in which static devices(power electronic devices) are used .
This makes the system more flexible in terms of control and regulation,and also improves system security and capacity.
Basically Facts controllers are made of static devices like SCRs , MCTs,GTOs,IGBTs etc in various configurations and ratings.
Advantages of FACTS are:
1.reactive power and voltage control
2.improves system reliability
3.easier to be be employed in existing systems for better efficiency or system upgradation
4.these controllers are compact in size
5.damping of power oscillations
6.Voltage flicker control
Various Facts Controllers are:
1.Thyristor Controlled Series Capacitor(TCSC)
2.Static Synchronous Compensator (STATCOM)
3.Unified Power Flow Controller (UPFC)
4.Thyristor Controlled Phase Angle regulator (TCPAR)
5.Thyristor Controlled Phase Shifting Transformer(TCPSC)
6.Interphase Power Controller(IPC)
Tuesday, February 10, 2009
Free Ebooks
I am posting here few very good ebook sites containing huge collection of books for electrical and electronics engineering students.These sites provide free download of these ebooks.
http://www.scidig.com/category/electronics
www.addebook.com/tech/category/engineer
RECENT TRENDS IN ELECTRICALS & ELECTRONICS
Today in this electrical age,for attaining better efficiency and reliability many new trends and technologies are being developed and practiced,i am mentioning few of them here.
Here i will also give few links regarding these topics that would enable to understand and grasp the topics better.
Disclaimer:The content in the links is neither owned nor created by me,they are owned by their respective owners and authors.
HVDC(High voltage direct current)
For bulk power transmission over large distance using dc is called HVDC.
For distances above break even distance(distance at which ac and dc transmission costs are equal),
dc transmission is employed because of technical advantages of dc over ac especially over long distance:
1.dc line by itself does not require reactive power compensation
2.as the distance increases difference in angles of voltage phasors of sending end voltage and receiving end voltage increase,more the difference less is the stability.No such problem is encountered in dc.
3.even for interconnection of two or more power systems or generating stations if ac ties are employed the frequency must be made equal and also control over the automatic generating units is difficult.Thus for such a purpose dc ties are used.
4.voltage regulation and control using HVDC is easier(high voltage converters are used).
5.ground impedance and ground current is lesser than dc.
6.using converters at converter station in HVDC current can also be controlled,thus minimizing the use of circuit breakers.
7.no power factor problem is encountered.
Basic components of HVDC sub-station:
1. high voltage converters(rectifier station and inverter station):For converting ac to dc at sending end then again converting from dc to ac at receiving end,since both generation and consumption is mostly in ac form.
2.dc filters,ac filters:these remove harmonics and ripples,further help for reactive power compensation (for lagging loads).
3.Smoothing Reactor:to smoothen the dc output of the rectifier converter station.
4.further multi-pulse transformers are employed to generate to converter stations,these improve output waveform as ripples are reduced.
Links:
1.High Voltage Direct Current Transmission-Proven technology for power exchange
http://www.energy.siemens.com/cms/us/US_Products/Portfolio/HVSystemsupto800kV/HighVoltageDCTransmissionSystems/Documents/HVDC_Proven_Technology.pdf
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