Question { 5271 }

if i have 5kw,9A,three phase induction motor,if i want to
install it 100 meter away from its feeder,how i will culculate
cable size for this load.

Answer

we have to use 4 core 2.5sqmm copper it will be economic
design since it can withstand 20a load
or we can use 4core 4sqmm copper

Question { ITC Infotech, 10012 }

what is meant by dielectric breakdown ? where we using HV
test kit & what purpose?

Answer

High-voltage transformers contain oil as their insulating
dielectric. When a critical electric field is exceeded,
conduction paths grow at microsecond speeds through the oil,
in the form of branched trees, called streamers. These can
lead to destructive breakdown.

Above a particular electric field, known as the dielectric
strength Eds, the dielectric in a capacitor becomes
conductive. The voltage at which this occurs is called the
breakdown voltage of the device, and is given by the product
of the dielectric strength and the separation between the
conductors

The high voltage test (also called dielectric strength test
or hipot test) can be made in AC or DC. If the high voltage
test is made in DC, it is then combined with insulation ;
if the high voltage test is made in AC, it is then, this is
then, more stressful for the sample and made according to
the sketch below.

Measurement of high voltage test under alternating current
is performed using an alternating voltage (50Hz) adjustable
to an effective 50V to 1,500V. As is the case with direct
current, the high voltage test detects any sudden rise of
current up to a programmed threshold.



http://www.sefelec.com/en/high-voltage-test.php

purpose
to test the insulators for their effectiveness. normally
used for transformer oil testing purpose.

Question { 5407 }

How can you measure the signal from the PT100 sensor?

Answer

The Temperature PT-100 sensor is a Platinum resistance
thermometer (PRT) which offers high accuracy over a wide
temperature range (from -200 to 400 °C). The Platinum
resistance thermometer (PT-100) has a resistance of 100
Ohms at 0°C, so it called as PT100. it offers 138.4 Ohms at
100 °C. The resistance changes (fearly linear) with
temperature are: 0.385 Ohm/°C.
by using a wheatstone bridge we can measure the change in
the resistance, which is in the form of voltage.

Question { 15356 }

WE HAVE A LOAD OF 55KW MOTOR ITS VOLTS 380 3PH AND ITS
TAKING 100AMPS (ITS FULL LOAD IS 105AMPS)AND ITS CABLE IS
4CX50SQMM ,NOW ITS GETTING ABNORMAL HEATUP IN CABLE,PLZ
TELL WHY ITS HEAT-UP?(CABLE LENGTH IS 15 METERS ONLY)

Answer

we must use above 70Sqmm Al cable for best results.

Question { 6177 }

If load current is 70amps or 50amps what range of CT to
install for ampere metering

Answer

i think u have to use 100/5A by considering initial load
currents.

Question { 19997 }

WHY HOLDING CONTACTOR OF MOTOR STARTER IS CALLED NO VOLT
COIL.

Answer

since if no volt is avialble for coil operation, it
isolates the motor from supply.
like that it protect motor from start on load when supply
resumes.

Question { Trimax, 6372 }

which motor used in electric train ans how much volt.

Answer

DC Series motor is used for the Train operation

incomming volts are 25Kv Ac single phase