meenakshi


{ City } coimbatore
< Country > india
* Profession * student
User No # 60493
Total Questions Posted # 0
Total Answers Posted # 61

Total Answers Posted for My Questions # 0
Total Views for My Questions # 0

Users Marked my Answers as Correct # 634
Users Marked my Answers as Wrong # 188
Questions / { meenakshi }
Questions Answers Category Views Company eMail




Answers / { meenakshi }

Question { ABB, 25993 }

What is the technical reason for adopting color coding of
three phase system as RYB.


Answer

to allow for balanced loading and to assure the correct
phase rotation

PLZ REFER TIS LINK FOR MORE DETAILS
http://en.wikipedia.org/wiki/Three-
phase_electric_power#Color_codes

Is This Answer Correct ?    3 Yes 2 No

Question { 13233 }

whatis the difference between electrical and electronics?


Answer

The number of differences between electrical and
electronics engineering may vary, depending on the context
in which the question is asked. Some distinctions which may
exist in academe may not exist in the business world. There
is also a significant amount of overlap, not only between
electronics and electrical engineering, but with other
engineering disciplines as well.
Electrical engineers generally deal with large-power
applications, such as utility and industrial power systems,
whereas electronics engineers deal with low-power systems
such as computers and communications.

Is This Answer Correct ?    2 Yes 0 No


Question { L&T, 14843 }

WHY WE NEED AUTO TRANSFORMER,WHERE WE CAN USE?


Answer

it has superior voltage regulation,higher efficiency, n
copper saving. and its mainly used to giv boost to
distribution cable for correcting voltage drop,as furnace
transformer for gettn a convenient supply to suit the
furnace winding,as interconnectng transformer n also as
control equipment.

Is This Answer Correct ?    3 Yes 0 No

Question { Juniper Networks, 17082 }

When we getting shock, its we getting from voltage or
Current.


Answer

cause of electric shock is voltage and its effect is only
flow of current.

Is This Answer Correct ?    2 Yes 0 No

Question { 20021 }

In a transformer ,when voltage decreases current increases.
but this is a violation of oms law.why?


Answer

ppl,Ohm's law is applicable only 4 those circuits which are
CONTAINING PURELY RESISTIVE ELEMENTS (NO INDUCTANCES OR
CAPACITANCES) for all forms of driving voltage or current,
regardless of whether the driving voltage or current is
constant (DC) or time-varying such as AC. At any instant of
time Ohm's law is valid for such circuits ONLY.

Is This Answer Correct ?    3 Yes 4 No

Question { 6147 }

v=I*R, i.e V is directly proportional to I.
now P=V*I. so V=P/I. thus v is inversely proportional to I.
so what is the correct one? If both are correct than for
which kind of condition this 2 differ


Answer

hey,ur question is wrong men...in the first part i.e, V
proportional I is correct in accordance vid ohm's law. but
in de second part,dc electric power is just an exact
multiplication of voltage and current.n there is no
relation as u say.vil make u understand r8 nw...juz considr
a ckt havn a 18V battery and a lamp of fixed resistance of
3 ohm.nw curnt thru de ckt is 18/3=6A.now am gona increase
voltge alone to 36V WITHOUT DISTURBN THE LAMP..now de curnt
vil b 36/3=12A. coming to the power,for the first case it
is 108W n for the second case its 432W (P=VI).now what u
ave to understand is,V inversely prop to I vud ave been
correct iff powers of two ckts were constant.but
practically speakn it is not so as u can very wel c frm the
above mentioned example.

Is This Answer Correct ?    8 Yes 1 No

Question { HCL, 5119 }

What is the difference between earthed & unearthed system?


Answer

By Earthed system, we mean a three phase system whose star
point is grounded directly. In this case, in the event of
the earth fault, the voltage in the faulty phase will
become zero. The voltage between the healthy phases and the
ground will be the same, 11kV/1.732 or 6.6/1.732.

However, in case of an earth fault in an ungrounded system,
the voltage between the healthy phases and the ground will
be equal to the phase to phase voltage. i.e. 11kV or 6.6 kV.

Is This Answer Correct ?    6 Yes 2 No

Question { TATA, 6473 }

What is rotating transformer? Which machine is used
specifically as rotating transformer?


Answer

usually induction motors are called rotating transformers.
in such motors,transfer of energy takes place from stator
to rotor inductively with the help of flux mutually linking
the two.thus induction motors acts as transformer vid
stator forming the primary n rotor forming the rotating
secondry.

Is This Answer Correct ?    34 Yes 0 No

Question { IOCL, 12242 }

If the damper winding on the rotor of a synchronous motor is
removed after starting what will happen?


Answer

damper windings are mainly used to provide startn torque
for sync motors.though under the normal running
condition,the damper does not carry any current since the
rotor runs at a synchronous speed, it cannot b removed.its
another purpose is to prevent hunting(i.e,momentary speed
fluctuation) n helps the motor to run @ sync speed by
preventing oscillations.

Is This Answer Correct ?    31 Yes 2 No

Question { Scope International, 4600 }

What is differential relay ? where it can be used?


Answer

Differential relay is one that operates when the phasor
difference of two or more similar electrical quantities
exceed a predetermined value. Thus a current differential
relay is one that compares the current entering a section
of the system with current leaving the section.Under normal
operating conditions, the two currents are equal but as
soon as fault occurs, this condition no longer applies. The
difference between the incoming and outgoing currents is
arranged to flow through relay operating coil. If this
difference is equal to or grater than the pick up value the
relay will operate and open the circuit breaker and isolate
the faulty section.
mainly used in two winding transformers

Is This Answer Correct ?    14 Yes 0 No

Question { 16207 }

CFL lamp is what type of load?


Answer

The lamp load itself is resistive, but the electronic
ballast that is connected between the AC line voltage and
the lamp for controlling the lamp current is a capacitive
load.

Is This Answer Correct ?    31 Yes 7 No

Question { NHPC, 9852 }

why we generate transmit and distribute electrical supply
in multiple of 11


Answer

There isn't really any electrical principle for that.
Originally Commercial Electric distribution was first done
by Edison and his Manhattan DC lighting system was opened
in September,1882.Edison took 100V as the voltage for his
incandescent lamps.( Why 100 V?Round number,safe electrical
voltgae to handle,but high enough to save copper in
conductors)But it soon became clear that at the fag end of
street the lamps were not burning well due to voltgae drop
in line.Edison had to raise the generator voltage to 110 V
( there by distribution voltage became 110V!)to take care
of the voltgae drop in line.thus it became a std in US.

N PPL, THERE IS NOTHING TO DO WITH FORM FACTOR AS U THINK.

Is This Answer Correct ?    17 Yes 11 No

Question { 4306 }

why t/f are rated in kva. is it conserned with p.f.


Answer

tranformers are rated based on the losses.the two main
losses of a transformer are copper loss n iron loss.copper
loss occurs in transformer whenever it is loaded(full load,
half load or whatever the load may be).thus copper loss
depends on current.but iron loss are constant losses,which
vil always be present no matter the transformer is loaded
or not.thus the total losses of a transformer depends on
volt-ampere n not on the phase angle between them. i.e it
is independent of load power factor.

Is This Answer Correct ?    9 Yes 2 No

Question { 3195 }

What do you meant by soft start?


Answer

many d.evices takes a large amount of current during
turning on condition(inrush current) which is an
undesirable one and may affect the performance of other
devices connected to the supply.so components vil b addedin
series to counteract this problem.Soft start is an
electronics term describing any circuit which reduces
excess current during initial power-up.

Is This Answer Correct ?    4 Yes 2 No

Question { 4605 }

Please explain how to do 'tan-delta test' on AC generator?
and where i get clear and brief detail, give any web page
address.


Answer

actually this tan delta test is done for checking the
quality of cable insulation.i vil jez giv u an idea.u plz
try tat in google search.its a pdf file containing a-z of
tan delta test.juz type tis n try....TAN δ (DELTA) CABLE
TESTING,OVERVIEW AND ANSWERS TO FREQUENTLY ASKED
QUESTIONS,BY high voltage VLF HIPOT INSTRUMENTS

Is This Answer Correct ?    0 Yes 2 No

 [1]   2   3   4   5    Next