-
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
-
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.
-
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.
-
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.
-
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.
-
Stray Capacitance
What is Stray Capacitance?
sreekanth_vigrahala
- Dec 24th, 2009
Stray capacitance is the imaginary capacitance which is exists between the winding turns.
-
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.
-
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.
-
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
-
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.
-
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...
-
-
-
Capacitor Banks
What is the best method to connect two capacitor bank?
behera.tapan
- Nov 13th, 2009
It is best to connect bank in delta because if connect in star it will required three times more?capacitance as?in case?delta for same reactive power supply and finally connect both bank parallel across load or out going feeders.
buntysurat
- Nov 13th, 2009
Capacitors should be connected in star with their star point is earthed. This arrangement reduces Phase voltage to each unit by root 3 and thus the voltage withstand capability of each unit. The star ...
-
-
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.
-
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...
-
Calculate Voltage Drop
How to calculate voltage drop in cables?
buntysurat
- Oct 23rd, 2009
Each Cable is specified with their R & X values per Km or Mtrs. For calculating Voltage Drop across cable the effective impedance Z must be calculated for given length of cable as Z = Square Root ...
-
Direct Current for Transformer
What happens when a transformer is supplied with direct current?
pmazulfi
- Oct 22nd, 2009
If DC supply is given to transformer there will be no change in the flux with time so there is no emf induced in the primary and secondary windings and hence transformer action will not take place.
-
What is the voltage drop for 100kw motor if the length of the cable is 200m and what is the cable size.
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
- 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...
Electrical Engineering Interview Questions
Ans