How can we chose transformer star to delta or delta to star connection? What condition is suitable for star connection? What condition is suitable for delta transformer?

mohammed

• Jan 18th, 2016

If we want to distribute to customers we use star connection but if we want to trasmit power we use delta connection

pdp

• Jan 13th, 2016

Delta star connection generates 73.2% more than dd and yy connection because star side requires less insulation than delta side in normal condition..we can put extra insuation to generate high voltage...

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If you are an electrical engineer in a factory what will you do if you found power factor 0.4?

Abhijeet

• May 18th, 2018

To improve power factor
1 start capacitor bank it will improve power factor immediately.
2 many industries use synchronous motor (condenser) to improve power factor. It has excellent features to improve power factor. Ns=120f?p by changing frequency(field excitation) hare krishna

Pavan kumar

• Oct 31st, 2017

We use syn. Condensers to improve the power factor

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When alternator is over exited, the power factor will be
a. Lagging
b. Leading
c. Zero

Dipti Ranjan

• Mar 7th, 2016

Pf is lagging because A.R is demagnetizing.

pradeep1987

 Profile Answers by pradeep1987 Questions by pradeep1987

• Jan 31st, 2016

It is lagging. When the alternator runs at lagging power factor, the armature reaction demagnetize the main field flux. To compensate the extra magnetic field required so that the alternator is Overexcited

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Neutral is connected to Earth at the source to ground, the unbalanced current in the electrical network mainly in distribution system, What happens if we connect neutral to earth at load side DB?

ashutosh singh

• May 24th, 2016

What is MD & MTTR?

ali raza

• May 21st, 2016

No because when unbalance current flow through neutral short circuit occurs at that point where neutral grounded

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Can mechanical energy be directly converted into electrical energy? Explain

Edwin Rodrigues

• Aug 3rd, 2016

Mechanical energy can be converted directly into electrical energy. Examples such as static electricity due to different material. Lightening.

Vinod

• Jun 11th, 2016

No, because withoit using magnetic domine its not possible to convert mechanical energy to electrical energy or electrical energy to mechanical energy, keep remember that without Magnetic fields these energy conversations are impossible till now...

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abishgk

 Profile Answers by abishgk Questions by abishgk

• Aug 13th, 2010

In salient pole synchronous machine has non-uniform air gap so the reactance will vary with rotor position. It has mainly two axis are there 1. Direct axis 2. Quadrature axis.

santosh soni

• Dec 21st, 2006

IN SALIENT POLE   SYN. ALTERNATOR IT  IS  THE  CHANGE  IN  THE RELUCTANCE  WITH SPACE  WHICH  RESULT  IN  GENERATION  OF  BOTH  RELUCTANCE  POWER & ELECTROMAGNETIC  POWER.

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sainathdi

 Profile Answers by sainathdi Questions by sainathdi

• Aug 16th, 2009

HVDC- High Voltage DC Transmission system ,from the name itself we can say that its a dc transmission system and a dc transmission has two conductors one phase and other neutral. phase conductor is us...

venky_sastra

 Profile Answers by venky_sastra Questions by venky_sastra

• Dec 28th, 2008

HVDC means high voltage DC transmission. Usually when we speak in common terms power p=I*I*R therefore p is propotional to I*I, A high voltage will generally involve low current so as a result the power losses are less. So it has an economic advantage over EHV-AC transmission.

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Why almost all large size synchronous machines are constructed with rotating field system type?

Rhombus

 Profile Answers by Rhombus Questions by Rhombus

• Jun 11th, 2011

All the large size synchronous machines have rotating field winding because in the other case where armature is rotating we require four slip rings.. but in case of rotating field we can do with only..2 slip rings..!! :):)

veerateja

 Profile Answers by veerateja Questions by veerateja

• Jul 11th, 2010

Large size synchronous machines or Alternators have rotating field winding on rotor for many reasons of them the important reasons are:- 1. The rotor can rotate at very high speeds. 2. The voltage reg...

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What is the effect of hysteresis loss in transformer/machines especially in DC one?

shad

• Aug 21st, 2015

But in PS Bimra book they said in transformer the hysteresis loss is inversely proportional to frequency..

bittu123

 Profile Answers by bittu123 Questions by bittu123

• Nov 7th, 2011

@ above, You are right in the sense that "Hysteresis loss depends on frequency". But there is some misconception, like 1. DC machine is having zero frequency (misconception???????, Relax..., I am n...

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What is meant by distributed winding and concentrated winding?

karthik

• Jan 20th, 2016

Concentrated and Distributed wiring definitions

Ravikumar Eta

• Jan 10th, 2016

In concentrated type winding, all the winding turns are wound together in series to form one multi coil.

In distributed type winding, all the winding turns are arranged in several full pitch or fractional pitch.

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List various methods to convert 1 phase to 3 phase.

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 14th, 2012

This can be done with thyristors

raviiisc

 Profile Answers by raviiisc Questions by raviiisc

• Sep 8th, 2010

This conversion is done by using mainly two methods. They are:1. Convert 1-ph ac to dc by using power electronic converter then convert that dc to 3-ph ac using power electronic inverter using PWM...

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Can we Touch phase wire in air when we r not touch ground what happens

amolgaonkar

 Profile Answers by amolgaonkar Questions by amolgaonkar

• Dec 9th, 2011

When you touch the phase wire in air the current will enter your body but it will have no way to escape or complete the circuit thats why you will not feel the shock...the best example is you might ha...

Tarun Aggarwal Ymca

• Jul 22nd, 2011

only high potential cannot cause flow of current. So, when a Human being touch such a wire, its whole body is at a high potential, but due to the absence of a lower potential, the current cannot flow....

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raj

• Dec 4th, 2011

3 Phase sys is preferred because of least amount of CU material required.

cvk

• Oct 6th, 2007

The instantaneous voltage at time instant 't' in a three phase balanced circuit assuming that the voltage is applied at reference time ZERO and phase sequence to be +ve ( anti clockwise rotati...

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soumendasbiswas

 Profile Answers by soumendasbiswas Questions by soumendasbiswas

• Oct 21st, 2009

1.The (0.48) is it resistivity of conductor ? or any other value  Well here 0.48 is the estimated voltage drop in XLPE cable.(You can get this value from any cable manufacture catalogue)2.You hav...

mustafa_musvi

 Profile Answers by mustafa_musvi Questions by mustafa_musvi

• Oct 20th, 2009

Mr Biswas please specify Below is the case you mentioned regarding cable losses I have 2 questions request for your answer1 The (0.48) is it resistivity of conductor ? or any other value 2 You hav...

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Answered by: cvk

• Oct 6th, 2007

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The series capacitor is conected to compensate for the line inductance and thus decrease the line reactance so that more power can be tranferred through the line (EV/X sin(delta)) and thus the system stability can be increased.

cvk

• Oct 6th, 2007

The series capacitor is conected to compensate for the line inductance and thus decrease the line reactance so that more power can be tranferred through the line (EV/X sin(delta)) and thus the system stability can be increased.

its_Kishu

 Profile Answers by its_Kishu Questions by its_Kishu

• Mar 10th, 2007

Hello......                The question is about connecting Capacitors in SERIES. Series connection is done for improvin...

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csbalu  

 Profile Answers by csbalu Questions by csbalu

• Member Since Aug-2009 | Aug 29th, 2009

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When there is a sudden loss of load, The Generator terminal voltage increases due to the fact that the IX drop in the generator winding decreases. The EMF generated being the same the reduced reactance loss leads to a sudden rise in generator voltage..but the AVR (Automatic Voltage Regulator) will act instantly to bring this voltage to the set value by reducing the excitation.
There is practically no effect of this on the transformer barring the reduction in I2R (copper Losses) and reduced IX drop.

csbalu

 Profile Answers by csbalu Questions by csbalu

• Aug 29th, 2009

When there is a sudden loss of load, The Generator terminal voltage increases due to the fact that the IX drop in the generator winding decreases. The EMF generated being the same the reduced reactanc...

spcspc1654

 Profile Answers by spcspc1654 Questions by spcspc1654

• Jul 19th, 2009

When there is a sudden loss in the demand then there is over-excitation of the generation and the power factor is increased. Also the rotor angle of generator is changed (unstable) for a while.

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panneer

• Mar 11th, 2015

Scott connections is used to convert either 3 phase to 2 phase and viceversa

p.srikanth reddy

• Jan 29th, 2015

It is used to convert 3-phase supply power to 2-phase power supply

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ilamurugan

• May 4th, 2014

Both source becomes single source of higher capacity and at the time of syn only entities are taken for reference. Once syn done its.single.source so need of current flow within that source

atul sudhakar

• May 2nd, 2014

In that case ,current flows due to the difference in load angle. synchronizing the system increases the efficiency of the power flow

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Why CTs are connected in star on T/F delta connected winding side & in delta on T/F star connected winding side for T/F differential protection?

Sandeep Nautiyal

 Profile Answers by Sandeep Nautiyal Questions by Sandeep Nautiyal

• Jun 5th, 2009

This to compensate the phase shift

bejoyengineer

 Profile Answers by bejoyengineer Questions by bejoyengineer

• Mar 1st, 2009

The differential relay will not activate when we energize the transformer as the relay will activate only if there is a difference in the flow of current and that to if it exceeds the setting values.

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Why does wattmeter's reading go negative?

bittu123

 Profile Answers by bittu123 Questions by bittu123

• Nov 9th, 2011

Suppose, phase difference between V and I is "A"(angle). and wattmeter reads +ve. Now if phase difference became (A+180), wattmeter will read -ve of same magnitude.

It simply means, direction of power flow gets changed just because of changing in direction of either current or voltage

SURAJTHEGREAT

 Profile Answers by SURAJTHEGREAT Questions by SURAJTHEGREAT

• Mar 3rd, 2009

If you have seen the wattmeter ratings, it will be (300V,10A,UPF) (Voltage, Current, Power Factor) That is wattmeter needs voltage and current to measure power.  So a wattmeter consists of t...

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