Answer / kh

3 core is used for 3-ph loads/systems which do not require
neutral e.g. motors. 3.5/4 core is used wherever 1-ph
supply is also required (tapped between 1ph-N) in addition
to 3 phase supply. 4 core used for smaller cables usually
upto 16 sqmm where neutral core is of same size as phase
cores while 3.5 core is used for higher sizes where neutral
core is half the size of phase cores.

Answer / at

3 core cables are used where ever the system is ungrounded.

3.5 core cables are used where the major load in an
industry / plant etc. is three phase but also has single
phase loads or loads that can cause a little unbalancing
and thus the nutral might carry some current but not always
and not as much as the line current. Therefore a smaller
cross section of nutral can solve the purpose as current
through nutral will be very small as compared to the rated
current of the cable.

4 core cables are used in systems where all loads are
single phase or majority loads are single phase. so there
are chances of high degree of unbalancing. and nutral has
to carry a larger amount of current.Therefore half cross
section of nutral may not solve the purpose and we opt for
4 core cables. This arrangement is used for small cross
section cables used in homes and industries. for lighting
and other small applications.

Answer / pawan mishra

3.5 core cables contain 4 cores i.e. 3 for phase and 1 for
neutral.
it is known as 3.5 coz it s netral thickness is half the
diameter of phase core.
netral is requried only in l.t. network

Answer / p.k.chadhar

3 core cable can be used for three phase power supply
without earthing
3&1/2 cable can be used for three phase power supply with
earthing because 1/2 core is mostly used for earthing or
gounding
4 core cable can also be used for three phase power supply
with earthing this cable can also be used for control supply
it depends on size of the cable if it is 1.5 mmsq.then
control ,if size is more can be used for power connection.

Answer / ashok

4 core cables are used for the rating more than 5KW,and the
3 core ,31/2 are used for below 5kw and 5kw supply.

For what purpose an AVR in generator sensing generator output voltage?and how the sensing is done by AVR?

3 Answers  

what is power transformer?

1 Answers  

Refernce currents are to be generated using refernce cueernts how can this be done??

0 Answers  

I want to apply for ONGC recruitment 2012 .I am BE Electrical but it is mentioned that to apply for this post you have to have Electrical supervisor certificate .so please tell me from where can i get such certificate ???

1 Answers  

How to calculate PF capactors for a connected load?

2 Answers   FD, Power World,

In iduction motors the current is higher than normal for both the cases when the voltage appllied is more than the rated as well as less than the rated, why?

2 Answers  

if there are six generators (3 gas CATT, one Jenbacher o1 MW each, and two nos Diesel 01 no 01 mw other 0.65mw EDGs ( say), 3 CAtt gas set have identical pole pitch,01mw EDG and Jenbacher gas Set have different pole pitch, how their power connection can be done to connect a common bus bar during installation. in short, how different pole pitched generators power connection can be done to connect a common busbar system through generators incomer ACBs.

0 Answers  

hello! can anyone explain to me how a 3 speeds table fan work? what are the factors that are controlling the speed of a normal table fan? Is it by varying the voltage or changing the magnetic field? would appreciate your reply :) thx in advance.

2 Answers  

In Air circuit breaker LSIG protection unit is used. Without fault in cables (2 runs 3Cx150Sq.mm Copper, 1Kv grade, XPLE armored cable IR value is more than 550Mohm @ 500V Megger) and load section Long time Overcurrent protection is triggers and trips the unit. We changed LSIG protection with new factory tested unit. Even then fault is persisting. Please suggest the possible causes

0 Answers  

What is meant by Load Encroachment in OHL Feeder Protection?

0 Answers  

how we select fuse rating for motor?

6 Answers  

Why is the earth pin in a 3-pin plug the longest and the thickest?

10 Answers   IBM,