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Is possible to increase the voltage without using transformer? why?
bittu123
- Nov 7th, 2011
I went through all answer, seems all are correct.... But lemme be more precise.. Except transformer..... 1. CHOPER: It is said to be DC equivalent of AC transformer, so can be used to increase and d...
santosh
- Nov 7th, 2011
We can step up and down dc voltage using chopper circuit
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What is meaning by the SKIN effect in electrical circuits
veerateja
- Jun 2nd, 2011
In ac electrical circuits due to varying magnetic fields they induce eddy inside the center of conductor .Due to the induced eddy currents they restrict the current flow on the center and pushes the c...
ravs42
- Aug 8th, 2010
When alternating current flows thru the conductor, magnetic field intensity in the inner side is more, as a result flux concentrated on the inner conductor is very high. Since inductance of the coil i...
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What are the general preparations a candidate should do before attending the inteview
SHATAKSHI
- Sep 2nd, 2011
You should be able to fully explain whatever you have written in your CV.
veena_gyanchandani
- Feb 24th, 2010
First of all You should be confident for yourself.You should know about the company profile in which you are going, and why you want to join that company, what is so interesting about that company?If ...
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At what condition a synchronous motor acts as a synchronous condenser?
arun uday rana
- Aug 8th, 2008
A synchronous motor act as a synch. Condenser when the its field winding is overexcited and there is no load attached with it. The basic application of this phenomenon can be seen in the hydro power p...
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What is watt?
bharath
- Sep 8th, 2011
It is the unit of power and used to specify the rate of electrical energy is dissipated.
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Current Circulation
Is it possible if their is no voltage then their is no current circulation or does it depend on circuit condition?
manojprabu
- Apr 4th, 2009
You are right without voltage their is no current circulation in any circuit (EMF is electro motivate forces is the force that produces movement of electrons in circuit if it is closed)Voltage is the major source of current.
arun uday rana
- Aug 2nd, 2008
Current is nothing but flow of charge inside the conductor. It is always true that any fluid or gas always flow from higher pressure to lower pressure (or temp.). It is same in the case of charged p...
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Earthing and Grounding
What is the difference between Earthing and Grounding?
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Current Transformer
Explain why the secondary terminal of current transformer should not be lift open circuited.
ravs42
- Aug 21st, 2010
Due to high ratio,if the secondary is left open a very large voltage will be developed at the secondary.As a result the core vl be saturated n operator working nearby vl face severe accidents.
deepanshu_jadon
- Mar 10th, 2010
In CT secondary side is not open because it has large voltage difference
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Inverter and UPS
What is the difference between INVERTER and UPS?
prafulla patil
- Oct 29th, 2010
The main difference between Inverter and UPS is switching time.Inverter switching time is inverter switching time is more than UPS , inverter Takes approx 500 millisecond to switch , that’s why ...
full61
- Apr 15th, 2010
Inverter converts only DC to AC but UPS converts AC to DC and then store it after that it convert DC to AC.
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OC/SC Test On Low Voltage Side
Why OC test is carried out on low voltage side of transformer?
mahmoudp1
- May 3rd, 2012
The previous answers are right + to make an accurate measurement O.C test on LV side because the current is high on the low voltage so when we repeat the experiment we will get more results with the ...
Pratyush Singh
- Jul 26th, 2011
Because during OC test, rated voltage is applied, hence the HV side is unsuitable to keep instruments, hence it is the HV side that is opened and the LV side is where instruments are placed (at their rated values)
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Reactive Power Relation with Alternator
How reactive power is related to alternator? Wheather it is generated or consumed? Explain
bittu123
- Nov 9th, 2011
If alternator is Overexcited, it will deliver reactive power with lagging current while in Underexcited, it absorb reactive power with leading curreent But, it always(under or over-excited) deliver ...
buntysurat
- Oct 23rd, 2009
An Inductive Load say Induction Motor connected to an Alternator requires Active (KW) & Reactive Power (KVAr) both. This Motor receives Apparent Power (KVA --> KW + KVAr) from th...
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Change in Frequency
Why do we maintain 50hz frequency? What happens when we change this frequency to any other value?
maxandrean
- Jul 5th, 2010
AC Electrical Network need to have a syncron phase for them to work. Any differences in term of frequency will shift out this syncronisation and lead the whole system to fail.
sankar_jkpm
- Feb 3rd, 2010
In our India, all the electrical power generation is based on 50 Hz. (50 cycles per second) with respect to the production of flux in alternator. So the electrical utility products are designed f...
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Transformer OC Test
Why OC test is conducted on low voltage side?
A.santosh
- Jan 27th, 2012
If want to conduct OC test on HV side we need more turns of auto-transformer, as an engineers we should have to decrease the cost required for the test, so normally OC test is conducted on LV side since we need less turns of auto-transformer
sinhasunilk
- Jul 12th, 2010
Voltage injection in LV side is convenient, The cable attached to LV side also need insulation suitable to LV voltage rating. If LV ia in the range of 440V and HV is of the range of 11KV, we may inject voltage in steps also through variac of 440V , Which is not possible if inject voltage in HV side.
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Transformer Signal
What is the benefit of using ac signal in a transformer?
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sinhasunilk- Member Since Jul-2010 | Jul 3rd, 2010
Transformer can only operate with A.C supply. Voltage will induce in the secondary winding of transformer only when there is a change in flux. The induced voltage in the secondary winding is no. of turns in secondary x rate of change of flux. In D.C circuit the rate opf change of flux is Zero, hence induced voltage in secondary winding is Zero and no Back MMF produce in the magnetic circuit of core of transformer.?This will result in very high current drawal in the primary winding and will result in burning of primary winding of transformer. We can not think of applying D.C source in transformer.??
SURAJTHEGREAT
- May 5th, 2012
The reason why dc signal cannot applied to a transformer is that f=0,reluctance is 0,very high current flows through windings and it is burnt out!
sinhasunilk
- Jul 3rd, 2010
Transformer can only operate with A.C supply. Voltage will induce in the secondary winding of transformer only when there is a change in flux. The induced voltage in the secondary winding is no. of tu...
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Measure Earth Resistance
How earth resistance is measured? What should be its value?
soulzangel
- Oct 4th, 2010
Earth resisitance can be measured using megger or earth tester and thr resisitance of proper earthing must always be less than 10 ohms and for sensitive installations such as very sensitive communication and computer systems about 2 ohms is recommended.
veerateja
- Jul 9th, 2010
Earth resistance is measured by means of earth tester or megger. The earth resistance must and should be less than 0 to 5 ohms. If it is above the 5 ohms we say earth resistance is not good.
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Transformer Humming
What causes transformer humming?
Krishna Kant Gupta
- Mar 13th, 2012
Humming sound in the transformer is due to the stray losses in the transformer due to the leakage flux.this flux produce eddy currents in the nearby conductive areas.The humming sound is the result of...
bittu123
- Nov 9th, 2011
Humming sound caused by magnetostriction phenomenon. Magnetostriction is change in physical dimension of material because of change in magnetic field.
Since, there is varying magnetic field in transformer causes vibration of core in gap available due to bad insulation. and starts soud hum
Electrical Engineering Interview Questions
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