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Does HVDC mode of transmission has an economic advantage over EHV-AC transmission. Justify
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
- 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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Large Size Synchronous Machines
Why almost all large size synchronous machines are constructed with rotating field system type?
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
- 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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Hysteresis Loss
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
- 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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Phase Conversion
List various methods to convert 1 phase to 3 phase.
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Touch phase wire
Can we Touch phase wire in air when we r not touch ground what happens
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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How do you detect the exact location of a cable fault if its cable puncture
suresharon
- Dec 27th, 2008
If it is a buried HT cable, you can avail the use of HT Cable fault locator which inject hi volt pulse into the cable and a person with an instrument can identify the exact location of the cable joint...
ramesh
- Jul 26th, 2007
You can find the fault by using murray loop test or wheatstone bridge test.
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How much voltage is present in neutral resistance?and how much voltage is present in earth resistance
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Editorial / Best Answer
abbasanwarali- Member Since Oct-2008 | Oct 16th, 2008
Actually there is no volt during normal condition. In case of any fault resistor will act as a low resistance path. because above mentioned components are high impedence components. so the huge fault (volt) will be grounded and the equipment remains safe.
HARESHKUMAR KHATRI
- Apr 4th, 2015
Absolutely there is no any voltage.
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How do you measure the leakage current in a house wiring?
bittu123
- Nov 9th, 2011
Two method suggested above is right.
Beside those,
Measure current through live wire and neutral wire at main switch board of ur house and find the differences.mani777
- Jun 22nd, 2010
There are two ways for it. First one is to keep all lights and other domestic electric appliances OFF for an hour and record the energy consumption in the energy meter. Calculate current from it. Seco...
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What is induction motor?
ajayyadav07
- Dec 28th, 2008
Induction motor is motor that work on the principle of INDUCTION, when the stator winding is connected to the supply mains then there is magnitic flux generated due to the flow of current in stator wd...
tarun aggarwal ymca
- Sep 28th, 2008
Inductor Motor based on the principle of induction, in this when we apply single phase AC current field is set up as motor winding are closed current is induced in them which once moved through any method (capacitor start) cut the magnetic field and force is exerted on the motor
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What is a Transducer?
BALLU_89
- Feb 21st, 2011
Transducer is a device which converts physical quantity into electrical quantity. As-Thermocouple (convert temperature into electrical volt or current) If it is correct then confirm me.
GeeK_Percy
- Oct 4th, 2009
Transducer is a device which converts any quantity into electrical siganls via mech displacement.
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Core cables
generally we are using 4 core or 3.5 core cable for power supply ,in this practice we are connecting three different phase R,Y,B and Neutral to our 4 core or 3.5 core cable,but for our termination conveniences we have connected R phase to all 3.5 core of one cable,Y phase connected to all 3.5core of other cable and B to another and similarly individual cable for Neutral,in sort we use individual cable...
loganathan.1983
- Mar 19th, 2010
3 Phase 4 Wire termination is better because insulation, eathing. Heat is increased according to routing (undergrounding/outer) and load.
expertnayak
- Jun 12th, 2009
Due to use of bundled conductors it will give rise to sheath losses. Which will increase the temperature to overcome this use cross bounding. In overhead lines use both cross bounding and transposition to get a better result.
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What is the voltage that is supplied to the electric traction trains
nileshvalvekar
- Aug 12th, 2009
Above both answers are correct but at some level. The ans. should be 1) 25 Kv Ac system2) 1500 V Dc systemabove voltages are used depending on the system being used.
haveasafeday
- Feb 5th, 2008
Right that it is 25kv ac. But the traction motor is a DC series motor for on-load starting.
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Why less loss occurs when we use DC supply than AC supply?
er.vikasharma
- Jan 5th, 2008
In DC, frequency is constent not zero,we say Skin effect & no corone loss occur is the main reason of less losses in DC then AC supply.
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Why frequency in India is selected 50Hz
bittu123
- Nov 9th, 2011
You are right, its all bout standerisation. Once standerisation is fixed for indian (50Hz) by british, so its continuing and In america its 60 Hz according to their standerisation. But real question...
Manohar Mathur
- Nov 13th, 2008
Our eyes have special property of retentivity (capacity of retaining object for few moments even when removed). Advantage of this has been used in cinema. If frequency of power supply goes below certa...
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Whats is difference between Earth and Neutral
ksubbu
- Feb 4th, 2009
Earth is provided to protect the equipments and appliances. It also protects us from shock hazards. Neutral is the return path for the current.
arun uday rana
- Jul 31st, 2008
Earthing of a system is to protect the system from high surge current/voltage due to lighening while neutral provides return path to the current flowing in the tranmission line.
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Power Factor
What is Power Factor? How it is calculated?
venkey_048
- Oct 29th, 2009
Power factor is the ratio between Real power to the Apparent power. It indicates, how much power was actually utilised by the present system. For example, if any system had a power factor of 0.8 mea...
Ravindra2008
- Oct 20th, 2008
In A.C. ckt their is some difference in vtg & current that angle is called as phase angle,the cosine of that angle is called as power factor. It is the ratio of resistance to impedance.
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Location of Circuit Breaker
The designed capacity of the transformer was 1600 watt. The utility company is in shortage of such wattage, so they used two 800 watt transformers in parrallel. The utility company uses only one circuit breaker after the parallel connection. The custmer says it is not correct there should be two separate breakers for each transformer. Which connection is accseptable.
VEERENDRAKUMAR.CH
- Jan 28th, 2011
when one CB used:if fault occurs on any one transformer that fault will effect the another transformer so two CB must be needed
appersundaram
- Mar 27th, 2010
We can use two circuit breakers in parallel, but we should connect the mastertrip relay contact of either breaker should be wired to trip the other breaker as well.
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Transformer induced emf
Is the transformer induced emf E1 and E2 in same phase or in opposite phase? Explain Why?
ripago
- Nov 28th, 2010
It depends on winding direction between primary and secondary coil ( this is so called polarity). If winding direction of primary and secondary coil same, then E1 would be in phase with E2. but if opposite then EMF also would be opposite (180 deg.)
kirank_239
- Mar 31st, 2009
The voltage induced in the primary and secondary windings is due to the same flux i.e., the primary flux. Hence E1 and E2 are in same phase
Electrical Engineering Interview Questions
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