Question { Uttam Sugar, 9290 }

on what factor insulation resistance depends

Answer

length and cross sectional area of rated cable

Question { 6003 }

what is the purpose finding power factor?

Answer

Power factor means cos of angle between real power and
active power (kw and kvah)and it should be 90 deg. that
means,power factor is unity.
Now if the angle comes down below 90 deg. the rective power
(kvarh)increases and that means your company pay extra
money for that power which we not use that is only losses
because in low power factor current lead voltage and due to
this copper losses increase and ultimately consumption
increase.
Finally purpose of finding power factor daily in any
company is that
1) To minimise the unwanted consumption
2) avoid heat losses and improving equipment life
3) and Electricity Board gives 7 per. discount in every
monthy bill if we maintain unity PF through out the month
but for that capacitor bank are required as per the load

Question { 8589 }

why current flows from +ve to -ve terminal

Answer

+ve is high potential side and -ve is low potential side
and electons always flow from high potantial to low
potential

Question { 15899 }

Is possible to increase the voltage without using
transformer? why?

Answer

Bu using capacitor bank u can increase voltage but not in
that manner and not step up

Question { Sail, 6518 }

What should be ideal IR value for 11kV, un earthed, 1 MW
motor?

Answer

Actually as the capacity of motor increase IR value
decreases.I am not exact correct but it should be less than
1 ohm

Question { 9239 }

which type motor r use in the celling fan.....

Answer

Ceiling fan having two windings starting and
running,capacitor are connected across the staring winding
for start the winding and afterthat running winding work in
the ckt. and the motor called compound motor

Question { Imdaad, 7104 }

2.5mva transformer is installed in our company with oltc
but it is not working in auto mode ,it is operative in
manual mode control wiring is done how can i rectify it?

Answer

Once you can try changing phase sequence of tap changing
motor.

Question { 7598 }

why do we prefer a 3-phase delta connected load rather than
star connected?

Answer

In star speed of motor is very low with low amp.
and in delta motor running with its normal rated speed with
rated amp.
So generally for motor starting purpose star used and
afterthat its change over to delta

Question { 7598 }

why do we prefer a 3-phase delta connected load rather than
star connected?

Answer

Dear Subhash
Yes speed of motor will remain same in star and delta both

Question { 5750 }

The neutarl to earth voltage in system is 7volts on
Electricity power but it lowers to 1.3volts when load
transfered to DG power.what may be the reason.

Answer

Its depends upon healthyness of earthing and nuetral. for
good earthing there should be minimum voltage drop between
earth and nuetral.
So from above example its clear that neutral or earthing of
Transformer not proper. It can be check by earth tester

Question { 9717 }

why battery is connected in parallel ?

Answer

If batteries are connected in series,its capacitance
decrease,addition of each battery and in parallel its a
viceversa

1) If we connect 2 capacitor in series its (1/c1 + 1/c2)

2) and if we connect in parallel its c1+c2=2c

Question { NTPC, 40289 }

What is 100%
protection of
generator? Why
95% protection
is used not 100%?

Answer

Generator having lot of protections rotar-stator wdg. earth
fault,over voltage,over current etc.
For that each relay having setting from 0-100 per. with
time period in seconds
According to type of fault we have to set the setting

example :- for earth fault protection we have set upto 50-
70per. because if we set to 100% every and each small
leakage relay trip

so my thinking is only that the setting of each protection
is depend up application of DG only on what load

Question { 7249 }

how the voltage between all the three phase is zero can
any body explain me

Answer

Only if you switch off the power during running of any
equipments its becomes zero. that means in switch off
condition only.

And yes the voltage can be unbalance which is totally
depends upon the load or phase failure during running

Question { Essar, 9486 }

how to identified power tranfer line is how much KV????

Answer

You can identify it by insulator, normally for 11KV one
insulator (PIN/Sc kale type) will connect.