MOHAMMED MUZAMMIL

• Apr 1st, 2018

So net voltage in the primary winding will be (Vin-0) more due to which primary winding draws more current which leads to burning of winding. ... But when a particular High DC voltage is applied to th...

phani prasad

• Sep 13th, 2017

Windings get burned

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What is the frequency of DC Voltage?

Gaj

• Oct 30th, 2017

Frequency is no. of cycles per second i.e. rate of change w.r.t time. DC has constant amplitude it means no change w.r.t. time. So it has Zero frequency.

Anup Kumar

• Sep 13th, 2017

Zero

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Answered by: NagaseshaReddy.M

• Sep 10th, 2007

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kVA is the unit for apparent power. Apparent power consists of active and reactive power. Active power is the share of the apparent power which transmits energy from the source (generator) to the user. Reactive power is the share of the apparent power which represents a useless oscillation of energy from the source to the user and back again.

It occurs when on account of some ?inertia? in the system there is a phase shift between voltage and current. This means that the current does not change polarity synchronous with the voltage. But the heat generated in a winding as well as the eddy current losses generated in a transformer core depend on the current only, regardless of whether it aligns with the voltage or not.

Therefore the heat is always proportional to the square of the current amplitude, irrespective of the phase angle (the shift between voltage and current). So a transformer has to be rated (and selected) by apparent power.

Raghu

• Feb 9th, 2018

In transformer there is two losses
1. Iron loss
2. Copper loss
The iron loss is depands on Voltage
And the Copper loss is depands on current.

Umar Naik

• Nov 26th, 2017

There are cu losses and iron losses which are not dependent on power factor thats why we rated it in KVA.

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KaranSorout  

 Profile Answers by KaranSorout Questions by KaranSorout

• Member Since Jul-2006 | Jul 13th, 2006

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The power ratio between Star to Delta is 1:3

Explanation:

 

Let?s suppose V_s be the supply voltage per phase.

So the line voltage of the supply will be ?3V_s.

Now assume any type of load; for simplicity I?m assuming it a only resistive load.

And let it be ?R? per phase.

 

For Delta connected load:

 

Calculation for per phase power; P_D= I²R

 

Where I ? load current (per phase)

And,

I = ?3V_s/R       {as line voltage of the supply is directly applied to the phase of the delta load}

So,

            P_d = (?3V_s/R )²R = 3V_s²/R  watts per phase.

For 3 phases:

            P_3D = 3P_d = 3*3V_s²/R = 9V_s²/R watts.

 

Now for Star connected load:

 

P_S = I²R = (V_s/R)²R = V_s²/R watts

For 3 phases: P_3S = 3P_S = 3 V_s²/R watts

 

Conclusion:

P_3S / P_{3D  =}  3V_s²/R / 9V_s²/R = 1/3

It may be better concluded by drowing figures. If any variations, can connect to me through karan.sorout@gmail.com  

RUP KAMAL KUTUM

• Feb 3rd, 2018

Well first you assumed voltage per phase as Vs and Line voltage as sqrt(3) x Vs: Which is for star connection. Then, you assumed the same thing for Delta Connection(where line and phase voltages are t...

Anbumozhi R

• Dec 3rd, 2017

Power is Same. Whether it is star to Delta conversion or Delta to star conversion. Power is 1:1

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What is the difference between Earthing & grounding?

chandramvs

 Profile Answers by chandramvs Questions by chandramvs

• Jan 3rd, 2016

Earthing and Grounding are nearly same where we connect the live parts of the machine to the zero potential(generally taken as ground or earth) in order to provide a bypass or excess or stray currents...

Rahul Patil

• Dec 24th, 2015

What is value of current flowing through earthing or grounding?

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Why the transformer will burn if DC supply is given?

Gajendra Singh

• Oct 30th, 2017

If we apply DC at input end then there will be no emf induced in the primary winding, As e=N*d(flux)/dt. Also leakage reactance (X1)and magnetizing reactance (Xm) will also be zero, coz (X=2f) and f...

saif

• Oct 2nd, 2017

The induced emf in transformer is change of flux linking with number of turns.... if we apply dc to the transformer there is no flux changes in transformer..... emf not induced...mainly winding will be burn

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deepak kapoor

• Dec 9th, 2016

True formula is Ns =120F/P

Sushil

• Oct 31st, 2016

Frequency is constant in a grid is because 1) All Equipment are designed for 50hz. Frequency 2) We genrate 50hz. 230 volts so in India all generation plant are 50hz. 3) All grid are inter-conected s...

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abhishek

• Apr 12th, 2015

Neutral is the return path of the conductor through which current flows back to the system, however earth is used for protection against high fault currents. when the current is very high it flows through earth and bypass the equipment thus protecting it.

hari

• Mar 27th, 2015

We know about that the neutral and ground is almost same means but in this most difference is neutral may be earth but we didn't say that earth is neutral. neutral some current have as 0.0000001Amp bu...

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SOURAV SINGH

• Aug 30th, 2017

Your answer is incorrect ajit nair, graveling is done to reduce step potential and touch potential.

Chisata bwalya

• Nov 11th, 2016

To reduce step & touch potential

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sanjay yadav

• Oct 25th, 2014

Current is the electron motion through external force. ? ? ? ? ? ? ?External force is applied voltage.

lalit

• Sep 27th, 2014

Voltage is the driving force that causes the current to flow in the closed path of the circuit. so if there is no voltage , there would be no current in that part of the circuit across the element

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for 3 phase AC supply Frequency= 50Hz, V =440 between 2 phase; then V = ? between phase and netural.

Bijit Maitra

• Mar 6th, 2018

254.04V Exactly

Anoar Hossain

• Jan 15th, 2017

254V

Code
1v1nn

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M.SANTHOSH KUMAR

• Aug 7th, 2015

Why we do not give DC supply in transformer means DC current is a direct current, so alternating flux is not produced, because input supply and flux will be same, so emf will not produced and same tim...

avdhesh sharma

• Aug 2nd, 2015

Current=voltage/impedance, When DC is applied then Z=R =>I= V/R and R is low for transformer, so I increases very high, so heating as current is not allowed to flow further and hence intuitively you c...

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Gaurav

• Jan 13th, 2017

Capacitor causes a lag in the phase, resulting in a good starting torque.

manoj yadav

• Sep 1st, 2016

Capacitors provide phase difference between voltage and current and give starting torque

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1. what is the different between CGS system and MKS system? 2. When we connect the capacitor Banks in Series with the circuit 3. What is the difference between Earthing & grounding 4. how much voltage is present in neutral resistance?and how much voltage is present in earth resistance... 5. What is the purpose of calculating knee point voltage for Current transformers? 6. What is the voltage drop for...

siva.naga.raju.bits

 Profile Answers by siva.naga.raju.bits Questions by siva.naga.raju.bits

• Jun 21st, 2011

100 MVA transformer is cooled by air blast cooling mechanism

SURAJTHEGREAT

 Profile Answers by SURAJTHEGREAT Questions by SURAJTHEGREAT

• Apr 10th, 2011

When capacitor is connected in series with the supply source (dc battery) ,capacitor gets fully charged and as a no current flows to the load!!!! When capacitor is connected in series with the supply source (ac) ,a leading current flows through the load.

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Answered by: joe

• Dec 23rd, 2006

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100 kw is the full load rating of the generator..... ..that means it can supply 100 kw without exceeding in specified temperature limits .that doesnt mean that it wont be able to supply a load more than 100 kw,it can but not for a longer period of time.after sometime the generator will burn out.if a load of 50 kw is connected to generator the generator will generate only 50 kw& not more than that.the generator will generate power only according to the requirement.

Dharmender

• Feb 7th, 2018

Connected Load is 96kw &125kvaDG set will have run stand by unit for Hotel is suitable plz give your technical supporting answer

Mayilsamy Kasipandi

• Jul 11th, 2017

The Generator produce the power is exactly what we withdraw as load. 100 kw genset can produce 1 kw to 115kw power depending upon the connected/withdrawing load. Normally the generator can produce 115% of designed rating.

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Yogesh Dandile

• Aug 4th, 2017

Induce high voltage

mUzammil

• Oct 7th, 2016

Tube light needed 1000v for ionization process for starting so choke provided its.

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Why transformer does not rotate like induction motor. Inspite both having same principle?

dhananjai

• Feb 3rd, 2012

Actually in 3 phase induction motor the windings are displaced with angle of 120 degree in space that is why a rotating magnetic field is produced while in transformer the windings are concentric rather than displaced

Avishek Pal

• Jan 21st, 2012

Transformer winding is made of concentric winding but the stator winding of induction motor is made of distributed winding over inner periphery. Hence flux in transformer is pulsating in nature and st...

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What is the purpose of Q-point in transistor?

MADHUSHREE SINHA

• Nov 9th, 2015

It is a DC operating point between saturation and cutoff. It must be selected in a way that it does not go into saturation or cutoff.

bala

• Oct 24th, 2015

It is more important for a transistor because according to this value, it may operate as an amplifier or a switch and most importantly the point should not vary with temperature hence we normally prefer voltage divider bias.

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Does it absorb reactive power when ever it is needed ?

Scott Munnings

• Sep 17th, 2018

A machine is run overexcited when VARs are needed by the house load or the grid. Running overexcited up to the machines rating is not necessarily a bad thing. VARs needed to magnetize other machines...

Scott Munnings

• Sep 17th, 2018

Yes. It is measured for both metering (billing) and protective relaying purposes.

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Why do we rate transformer in KVA not in KW?

s harikumar

• Nov 16th, 2012

Transformer rating in KVA instead of KW since its iron loss depends on voltage and copper loss depends on load current only. It is not dependent on the power factor of the load.

pinaki patra

• Oct 10th, 2012

For a transformer power factor is dependent on load, which is variable. Hence fixed quantity VA is used in place of watts.

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