Question { 11209 }

what is meant by phase &line voltage, how its differ from
each other ?

Answer

in a 3phase four wire system the voltage between two lines(R-Y,Y-B,B-R)is said to be line voltage, the voltage between any one of the three lines and neutral(R-N,Y-N,B-N)is said to be phase voltage.
its measured VL= /3*Vph

Question { 11565 }

Why the stator is rotated in ceiling fans not Rator?

Answer

usually rotors are inside(rotating) and stator is outside in squirrel cage motors, but in case of ceiling fans constructionally same squirrel cage rotor is made as ring and kept out side to connect wings to rotate and stator is fixed is kept inside.

Question { Amway, 5756 }

if the power factor is .88 i want to increase the power
factor to .99 what number of capacitor is to add?

Answer

The kVAR of capacitors necessary to raise the power factor to
0.99 from 0.88 is found by using formula referenced above:
0.398 x 50 kW = 20kVAR
this also depends on at what load are we used

Question { 4264 }

What is an Isolation Transformer? Where it will use?

Answer

for impedance matching and isolation.

it is used when there is a requirement to isolate the power ckt with control circuit and to transfer the pulse.
example: thyristor working in 415 volts firing circuit under 5volts.

Question { TVS, 4052 }

1 hp single phase motor is more likely to get hot thsn inone
hp 3 phase
motor its true or false? If true why?

Answer

single phase 1hp motor carries 4 ampere and in case of 3phase motor of 1hp carries 1.28 ampere in each phase . temperature is depends on square of current ie., i*i*r

Question { 6541 }

how does a tube light choke working?

Answer

Fluorescent tube is a gas discharge lamp. It consists of two
filamentary thermionic electrodes mounted at each end of
long cylindrical glass tube. The tube is filled with an
inert gas like mercury at low pressure and sealed. A high
voltage is necessary to start conduction through the tube.
To obtain this high voltage during starting an iron cored
choke and glow type starter are connected in series with
filaments. When the supply is switched ON an arc is struck
between the starter electrodes which causes a current to
flow through the choke and filaments. The filaments get
heated up and emit electrons. After a few seconds the
starter electrodes separates and due to this separation
current is interrupted. This interruption causes high
voltage to be induced in the choke which appears across the
filaments of the tube resulting in discharge through the
tube. The gas inside the tube is ionized and the ionized gas
emits ultra-violet radiation which is absorbed by the
fluorescent material coated inside of the tube this in turn
emits light radiations causing the tube to glow.

Question { 4132 }

how does a tube light starter works?

Answer

Fluorescent tube is a gas discharge lamp. It consists of two
filamentary thermionic electrodes mounted at each end of
glass tube. The tube is filled with an inert gas like
mercury at low pressure and sealed. A high voltage is
necessary to start conduction through the tube. To obtain
this high voltage during starting an iron cored choke and
glow type starter are connected in series with filaments.
When the supply is switched ON an arc is struck between the
starter electrodes which causes a current to flow through
the choke and filaments. The filaments get heated up and
emit electrons. After a few seconds the starter electrodes
separates and due to this separation current is interrupted.
This interruption causes high voltage to be induced in the
choke which appears across the filaments of the tube
resulting in discharge through the tube. The gas inside the
tube is ionized and the ionized gas emits ultra-violet
radiation which is absorbed by the fluorescent material
coated inside of the tube this in turn emits light
radiations causing the tube to glow.

Question { Mukand, 42626 }

What is the difference between UPS and SMPS?

Answer

UPS gives power supply to AC load when supply is interrupted
SMPS give pure DC supply at different voltage with almost zero
ripple

Question { 5401 }

Define Current Transformer?
Working & TYpe's Of C.T.

Answer

it is a device which works on the principle of mutual
induction.
it consists of two windings with thick copper windings of
perticular ratio. primary winding is connected in series
with load to carry load current and it is induced in
secondory is connected with a appropriate meter to measure
load current.