Question { Emerson, 11671 }

How many no. of earthing pits required for commisioning a
new 320KVC DG Set????How????

Answer

2 nos Cu earthing for Neutral Earthing & 2 nos GI Earthing
for Body... Total 4 nos...

Question { 9544 }

what is creepage distance

Answer

Above ans is correct but example wise in in substation the
distance between live part of insulator & the nearest
earthing point is called a creepage distance

Question { 5965 }

how many types of ct retio

Answer

one -/5 ( - means the rating of CT )

Question { Carrier, 62448 }

What is TR of AC?

Answer

TR means the tonage capacity of the Air Conditioner to cool
the room of ( 10 x10x10 Ft ) Room for certain period of time

Question { 17834 }

How many earthings are provided for a 250KVA distribution
transformer?

Answer

Total 4 earthing 2 Nos for Body earthing & 2 for Neutral
earthing & also interconnect both the body earthing to each
other & same as in neutral earthing.

Question { 9097 }

What is the function of lead sheath?

Answer

The function of Leas sheath to prevent the moisture
entering in to the cable

The mechanical damage protection is provided by Armoured.

Question { RVNL, 8067 }

how to caculate cable size for given amperes

Answer

current carring capacity might gets slight change dependign
upon the manufacture. but in coomon practice as amarnath
said Aluminus takes 1A per sq.mm but for Copper it is 1.6 /
sq.mm

Question { Hyundai, 9877 }

Hi All,

I am working as a Technical executive in a MNC company and
we have 1500KVA & 1250KVA T/F in our site, can you help me
that how many maintenance tests can be conducted and what
are the procedures included for the tests can you share
yours answers and also give any web address to get more
information on this

Answer

Dear friend ,

Transformer is a heart of the electrical system & that is
the reason it required more care.

Daily :-

Check the Oil level in Conservator.
check for any leakage in transformer
Check for any abnormal sound
check for Colour of silica gel.
Check for any air in Bucholz realay , if found realease
with the air vent provided in the relay.

Yearly.

Check the Dielectrica strengh of oil , filter it & if
required replace it.

Check the earthing value of a Earthpit if required topup
with salt & water.

Check the tighness of the connection both the way Primaty
side & secondary side.

Clean the transformer yard throughly.

If required lay the granuals in the transformer yard.

By proper shut down manually check the tripping point of HT
breaker tripping set points like ( OT, WT & Bucholz Relay )

check the secondary side voltage as per desired voltage &
if any missallign found adjust with the tap changer.


please revert if any quarry exists.

Question { TCS, 9737 }

WHAT IS THE DIFFERENCE B/W BUSHINGS AND INSULATORS?
WHAT IS THE CREEPAGE DISTANCE ?

Answer

shortest distance between two conducting parts along the
surtace of the insulating material called a Creepage
Distance.

Question { 9336 }

why motor burns ?

Answer

When mototr takes more current then its rated capcity then
the insulation gets weeken of the winding & its results in
to flashover between two winding or winding to ground & it
gets burnt

Question { 7672 }

Why air gap in rotating machines should be small?

Answer

To reducet the leakage fulx

Question { 5264 }

which is the slowest motor? and wt is speed ?

Answer

It is stapper Motor ( Speed is As you desire )

Question { JSL, 12492 }

how induction motor starts?

Answer

Yes, as armine said that there is a diffrent method for
starting both the motores in single phase more it can be
driven as capacitor start, capccitor run ,also capacitor
start capacitor run motor.

Considering a three phase motor when three phase supply is
given to the startor winding rotating magnatic field is
developed which rotaes with syschronous speed ( NS =
120F/P ). now this magnatic field is connected to rotar bar
& as the rotar winding is shot ( in case of Squrell cage
rotor through copper ring & in case of sleepring rotor
through resistence ) so the current flows in rotor bar .
now as this in magnatic field . the force is applied on the
rotor . rotor start moving & as the magnatic field is
rotating rotor keep moving but is legs behind a bit then a
synchronous speed & this phenomina called a Slip.

please revert if any querry exists.

Question { 24439 }

how to calculate the bus bar current rating

Answer

Bus Bar current rating is based on amount of Current to be
carry. The current carring capacity is 1A / Sq.mm & 1.6A/
sq.mm for Aluminum & copper respectively.

Ex if the 200 Amp load is required to be carry then the (20
x 10 MM ) Aluminum strip is required & the same way (25 x
5 MM ) copper strip is Required.

ofcource the length is also play a little part in this

Question { 9076 }

If a motor of 8.5 KW with same load and using in both Star
& Delta one by one,then which will take more current in
star connected or in delta connected

Answer

IF motor is started using a delta starter then VP=VL (
Phase voltage is equall to line voltage & Load current Isc
is become root3.Isc.

Now if this motor is connected in star then then VP=VL/root3
& IP= isc /roor3

It clearly shoow that in star connection motor take 1/3
times less current then starting in Delta.