Answer / sharad

A soft starter is a solid state motor starter that is used
to start or stop a motor by notching the voltage waveform,
thereby, reducing the voltage to each phase of a motor and
gradually increasing the voltage until the motor gets up to
full voltage/speed all at a fixed frequency. The profile of
the increase of voltage depends on the application. The
voltage is reduced and controlled by 3 pairs of back-to-back
silicon-controlled rectifiers (SCRs), which are a type of
high speed thyristor. A soft starter takes the place of a
contactor and can also take the place of an overload relay
in a standard motor starting application.

in india why we not use frequency above 50 hz for distrubuting power ?

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sir my exam is on 19/6/2013 under electrical branch pls send me sample aptitude questions as well as sample technical questions for jindal steel and power company

0 Answers   Jindal,

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Why in Hv transmission line as we see there are generally 6 or more than 4 conductor wires are used instead of 4 i.e. 3 for phase and 1 for neutral wire?????

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Is Indian railway uses 25000v ac or dc?

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Hi, I'm running plastic reprocessing company where all motors are running only in delta. Due to that when I use start my 30 hp motor my transformer gets fuse. Where it happens two times a day. I gt a suggestion from a person about Automatic Power Factor Controller APFC. Is it useful for my problem??? Or is der any other way for solving this problem?? Upgrading the transformer is difficult. Pls give Me ur suggestion. Waiting for ur reply.

2 Answers   Shree Lingaa Polymer,

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Different STANDARDS (BS, IS, IEC etc) gives different informations on CT specification. How they correspons w r t each other (i.e I mean to say BS provides "knee point voltage" but IS does not, then how can i select CT)

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What is primary distribution and secondary distribution of ac power?

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Dear all, i completed M.E(Power Electronics & Drives) 2011 passed out having 78% so i need job in core side but i don't know how can i receive the calls from electrical companies and i uploaded my CV in naukri, times jobs etc.. In that iam not recieved any mails from good companies so give me best procedure plzzzzzzzzzzzzzzzzzzzzzzzz..... Thanks, K.Linga Reddy Email-id:-lingareddykmthm@gmail.com Ph no:-08015402078

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We know that, in case if there is a faulty insulation,or sc, the current is bypassed to earth through the earth wire that has low resistance.Actually, what will happen to that current that flows through gnd?In that case,if we come in contact with that faulty appliance, wont that current flow through us as we form a closed path by standing in gnd?Is grounding a safety measure?

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What are the advantages of vscf wind electrical system?

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E.B sending end to receiving end 33kv ug cable laid 8Km,receiving end to ss1,ss2,ss3,ss4 all are Approx 800 Mtr,can go for 33KV to 430V or 33kv to 11kv in receiving end and 11kv to 430 near ss ,which one is good for technically and economically.

1 Answers   JLL,

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an off load but energized 11/0.4 KV, 1250 KVA T/F has a power factor of 0.65(capacitive)..!! why is it so, though T/F being an inductive device ??

4 Answers  

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