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Explain the operation of a transistor
behera.tapan
- Nov 22nd, 2009
Generally there are three mode of transistor operation .1. Common emmiter2. Common collector.3. Common base.For example in common base connection make base is common with respect to (wrt)emmiter and c...
behera.tapan
- Nov 19th, 2009
Generally there are three mode of transistor operation .1. Common emmiter2. Common collector.3. Common base.For example in common base connection make base is common with respect to (wrt)em...
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Alternator capacity
Is it possible to increase the capacity of a synchronous generator upto 30% to 50% just to modify the cooling system but the other component remain same? Explain
Raman Jain
- Dec 3rd, 2009
Yes , one can increase the capacity by efficient cooling. This may be possible by modification in design , using better coolent etc.
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Specific Gravity of Fully Charged Lead Acid Battery
What is the Specific Gravity of Fully charged Lead Acid Batteries?
prabhat.gaurav
- Dec 8th, 2009
For Fully charged bateery specific gravity is 1.265 and its specific gravity starts decreasing with the discharging of battery. and for fully discharged it's spec. garvity is around 1.120
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Form Factor
What is the link between Voltage and Form Factor?
lynxrat
- Dec 13th, 2009
Voltage is an electrical field, form factor is the actual size and shape of a device or piece of hardware.
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Purpose of Earthing
What purpose does an earth serve on a generator terminals if the generator was started accidentally.This a true incident when the generator was started it blew the earth wire because the terminals were shorted and then earthed to ground. What is the point of earthing if it cannot save the generator or the personnel.
nrathi.thb
- Dec 23rd, 2009
The earthing wire was not of proper size to bear the fault current & may be also the earthing was not done as per specification.
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Stray Capacitance
What is Stray Capacitance?
sreekanth_vigrahala
- Dec 24th, 2009
Stray capacitance is the imaginary capacitance which is exists between the winding turns.
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Cable Selection
What is the max current rating for a 4 core * 1mm^2 cable?
anilsabaji
- Jan 8th, 2010
It varies depending on the material and the Temperature rating of the cable. You can safely use it for 5-7 Amps though the maximum rating can be up to 12Amp.
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Voltage Source
What would happen if two voltage sources of different magnitude are connect in parallel?
anilsabaji
- Jan 8th, 2010
If the two sources, say batteries with voltages V1 and V2, and internal resistance R1 & R2 are connected in Parallel, then a current equal to to (V1~V2)/(R1+R2) will circulate between them assumin...
nagarjuna227
- Dec 20th, 2009
We cannot find the voltage across two different magnitude voltage sorces.
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Open Rotor Conductors
What happens with squirrel induction machines if the ends of rotor conductors are kept open?
anilsabaji
- Jan 8th, 2010
If the end of the Rotor Bars are not connected then there is no current in rotor Bars and hence no torque will be developped. The moroe may however run at a very low speed due to eddy currents in the rotor.
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22 KV Cables
What are the maximum number of joints you can make in a (3x300mm, 22KV) cable over +/- 610m?
anilsabaji
- Jan 8th, 2010
There are no such rules. In some cases Cable Joints are strictly not allowed (in ships carrying Gas). Practically, as long as the joint does not increase the resistance of the cable than if it is not having any joint, it is acceptable for general industrial applications.
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Location of LA (Ligtining arrestor)
Where do we locate lightining arrestor in transmission line?
anupam_srivastav
- Jan 9th, 2010
Ligthing arrestor is mounted on the starting of S/s as well as near T/f for the protection of equipment. Lightining arrestor has nothing to do with lightining it is mounted there from protection from lightining surge. Ci cover & lightining Mast is used for Lightining Attack.
ashok.bhaarath
- Dec 10th, 2009
Ligtining arrestor is placed in Starting of the Substation because of avoiding the over currents &voltages
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Find Fault in Underground Cable
How to find out cable fault in a long underground cable?
napster.zatac
- Jan 23rd, 2010
Sectionalizing: it is risky and reduces cable reliability, because it depends on physically cutting and splicing the cable. Dividing the cable into successively smaller sections will enable you to na...
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Syncronous Generator Flying Off
One advantage of syncronous generator is that there is no possibility of armature conductors flying off. What do you mean by flying off?
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Variable and Core Losses
Why copper is called variable loss & core loss is constant loss?
SURAJTHEGREAT
- Feb 22nd, 2010
Iron loss-When an electric current flows through a copper conductor (or any conductor), some energy is converted to heat. i(square)*r...this equation is obvious that iron loss depends on flowing curre...
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LV Switchgear
Considering the short circuit fault, which switchgear is preferable, SFU OR MCCB? Which operates faster?
which one is popular in Indian Market and why? 2) Define SCPD. What is type2 co-odination?
3) Why the contactor rating is higher for the fuseless selection than for fuse selection? whether the ratinf of SFU or MCCB remains the same in both the cases?
4) If...veena_gyanchandani
- Feb 24th, 2010
2) SCPD - Short Ckt. Protection Device.eg - SFU.Type 2 coordination says that there should be no danger to personnel as well as no damage to the controller for downstream faults.Light contact welding ...
veena_gyanchandani
- Feb 24th, 2010
During short ckt. faults, the most reliable switchgear is SFU. It is fastest to operate and takes only few miliseconds. The operator just has to replace the fuse.MCCB is good for overload protection.
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Phase Sequence
What happens when we change the phase sequence in 3 phase system?
R Raghavendran
- Feb 26th, 2010
Only the sequence of rotation of Magnetic fields changes, which causes a change in the rotor rotating direction accordingly.
SURAJTHEGREAT
- Feb 22nd, 2010
There is no change for ordinary devices,(behaves same as if the unvaried 3 phase supply is given) The rotation direction of the machines varies with variation in sequence of ac supply..
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3 Phase Motors
Why do 3 phase motors rotate in the opposite direction when any two phases are interchanged?
deepanshu_jadon
- Mar 10th, 2010
By the interchange of two phases Force acted in the winding inverse.if motor rotate clockwise then by the changing the two phases it start rotate in anticlockwise direction
M.Mohanraj
- Dec 8th, 2009
Magnitude is different in 3 phases so it is possible to rotate reverse direction.
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Network Synthesis
Why the roots of the network function are +ve?
deepanshu_jadon
- Mar 10th, 2010
Roots of the network function should be negative for the stability of the function.For positive roots network function is unstable.
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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 main Electrical IS rules?.
yuvaraj moorthy
- Mar 25th, 2010
ISO is international standard organisation and IS is Indian standarad ...ISO has IEC which is International Electrotechnical Commision will do the standarad for all equipments and each national interp...
vishwas_deshmukh
- May 6th, 2008
IS rules is international standrds rule adopted for any comissioning,erection,or any work we want to perform.They have some certain standads according to study of researcher by comparing all geographical and availabe technical parameteres in that concerning area.Which is suitable for any work.
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