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Fault Detection in Underground Cables
If there are three underground cables if a fault takes place in one of them, How will you detect it?
pradipsabar2009
- Jul 28th, 2010
Measure the resistance of each cable between farther ends, if there is a considerable variation in any one of the cable, that is the faulty one. This method is also used in industries called as "Insulation Resistance Test".
dhands
- Jun 6th, 2010
1. Check phase to pase insulation resistance value and phase to earth insulation resistance value.
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Power Factor
A powerplant has 8 gensets operating in grid parallel mode. In one genset sometimes there is pf variation and kvar variation. The plant operates in pf mode. When this variation is onbserved the load is stable, voltage is also stable, freq and genset speed is also stable. How will you check the functioning of pf card. What shall be the ideal output vdc of the pfc, from there it is input to avr.
mani777
- Jun 23rd, 2010
1. pf...........cos #=watt/voltage*current2. pf is cos thita between v & i3. pf is apperent power/realor reactive power.
saginala13
- Jun 19th, 2010
here the variation in the power is is the pf factor of load, in generating station all alternators are connected to a busbar, and load is connected to bus bar so the load will be shared by all generators
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3 Phase Motor
How can we test a 3 phase motor on single phase supply?How can we run a 3 Phase Motor on Single Phase supply for testing?How can we verify of a 3 phase motors' 6 wire & name them a1/a2/a3..b1/b2/b3 and c1/c2/c3 for connecting star delta starter?
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Power Factor Panel
What will happen if 400 KVar Capacitor banks are on in manual mode and there is no load on mains?
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Water Level Sensor
What sensor is used to measure the level of water in a tank?
thakur.rajesh.ranjan
- Sep 25th, 2010
A small rubber ball, we generally use in our dewatering sump for water level sensor. This gives command mechanically to level switch.
ravs42
- Aug 6th, 2010
A simple mechanical model for water level indicator includes a float(rubber ball) providing? a mechanical link to the indicator i.e. d output. When the water level rises the float due to it's light weight raises up and via the link the pointer will move to display the required output.
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Reactive Power
How much reactive power does a generator of rating 3.5MW generate?
Raman Jain
- Jan 3rd, 2011
The reactive power , Generator can supply, can be determined by the Capabilty Curve of the Generator , supplied by the manufracturer.This is a design criterion.
raviiisc
- Sep 8th, 2010
Generally the Alternator or Generator is rated in MVA format rather than MW format.The reactive power supplied by the generator is then decided.I think the questioner thinking about the ratings provid...
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Apparent Power and Reactive Power
What is apparent power and reactive power?
Steeve Cantave
- Mar 15th, 2011
Apparent power is the power that is needed for the circuit to perform. In an AC circuit with resistive, capacitive, and inductive components, not all power is converted from electrical to non-el...
zaheerdahri
- Dec 23rd, 2010
Apparent PowerApparent power (S) is the power delivered to an electrical circuit. The measurement of apparent power is in voltamperes (VA).Reactive PowerReactive power (Q) is the power consumed in an ...
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Tubelight Stator and Choke
What is the use of stator and choke in tubelight?
G.Harish
- Nov 19th, 2016
It gives initial current to bulb
rohansharma
- Mar 26th, 2011
Choke Coil : for producing a very high voltage across the terminals of Tube Light.Starter : It applies that high voltage suddenly to the tube light filaments, which makes ionisation of the gases in the light.
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Transformer Principle
Explain the transformer principle in terms of induced e.m.f. resulting from changing flux linkages?
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Why is r.m.s. value used to express a.c. quantities?
SURAJTHEGREAT
- Apr 10th, 2011
AC values are always alternating.Hence we cannot make a precise analysis!!!!So we use RMS value.Let us consider a bulb B.IF it is switched to position A(it is connected to ac supply).IF switched to po...
raviiisc
- Apr 9th, 2011
The rms value arised in the following manner:The heat dissipation with AC supply will found, then the DC supply is applied such that same heat production in resistor. That DC voltage value is said to ...
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How size of UPS depends on frequency?
How size of UPS depends on frequency? I mean proportional, inversely proportional or proportional to square of frequency?
Umair Anwar
- Nov 13th, 2014
Because core size of transformer directly depend on frequency and transformer primary element.
bittu123
- Nov 8th, 2011
Actually i mean SMPS not UPS.
Please moderator, if you can change my question please do it.. Replace UPS by SMPS since i didn't get any option to edit my question -
Meaning of RJ11
Could you elaborate in detail about RJ11 and what does "RJ" and "11" stands for?
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What is welding transformer ?
Why we use it in welding and what is the difference in welding and ordinary transformer?
Srinivas
- Dec 20th, 2011
Welding transformer is used for welding purpose, these are the special type of Transformer. which will be having only few turns on secondary side of the transformer winding. it will operate at low voltage in the range of 60 to 110 v Ac where as current will be very high upto several thousand amps.
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What is the use of a VCT
What is the use of a voltage capacitor transformer?
sjw06
- Apr 15th, 2012
VCT is used to step down really high voltage to a very low voltage that can be safely fed to a measuring device or protective devices.
Harish P. Girhe
- Apr 3rd, 2012
Generally all transformers works on inductive load hence operated at lagging power factor. It is necessary to use an capacitor bank for improvement an power factor. This capacitor bank called as VCT. Generally this VCT known as RVT (Residual Voltage transformer)
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Supply Voltage 220V, 110V or both
Why do some countries have 220V supply while some have 110V and some even have both ?
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Induction Motor Power Factor
A 3-phase induction motor running on 500v at full load draw 40A current at 0.85 pf Lagging if 85 micro Farad capacitor connected across its terminal than what would be a New Power Factor?
mahmoudp1
- May 1st, 2012
You didn't specify the capacitors connection is delta or star
assuming (delta)
Xc = 37.462 ;
reactive power drawn by capacitor = 6684.49 VAR
active power drawn by motor = 34641 watt
old power factor = .85 lag
new power factor = .91 lag
vishnu
- Feb 18th, 2012
--> Find the reactance offered by capacitor i.e 37.46 ohm. so leading current drawn by capacitor is 9.095A @90 deg lead. --> Current drawn by the motor is 40A @ 31.788 deg lag. --> Resultant current ...
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Making electricity
Can electricity be made by reversing. Other words can you make electricity by spinning magnets around copper wiring
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Power Produced in Generator is either ACTIVE(kW) power or APPARENT (VA)
Power generated in the generator is active power or apparent power? Will there be any phase lag while generating power? How the reactive power is produced (either by capacitor or the generator itself generate it) ?
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Electrical Engineering Interview Questions
Ans