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Transformer Taping
Why tapings of Transformer is always provided on HT side? why not on LT side?
ravs42
- Aug 21st, 2010
It is because of two reasons1.high voltage regulation.Large range of voltage can be obtained.2.less current value on the HV side,as a result,no sparking problem.
Raman Jain
- Dec 3rd, 2009
Tapings in transformers are provided at HV side . The reasons are : 1. Less current has to be handled .2. As the LV windind is wounded first i.e near the core and HT winding is wounded on the top of the LV winding. So it is easier to provide Taps on HV side.
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Run DC machine as a Generator
It is possible to run one DC machine as a generator or motor purposely? What adjustment we have to do for that operation?
ravs42
- Aug 21st, 2010
DC generators has got some limitations. The machine speed and output cannot be increased above certain limit due to commutation problems and cost. Besides using an alternator along with a rectifier circuit can be the best option to generate DC supply.
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Synronizing Degree
In which degree synronizing has to be done in a 3 phase alternator?
mgbushan
- Aug 24th, 2010
When you have to synchronize the alternator with the reference bus, then The voltage, Phase angle, frequency difference of the alternator with refernce to the bus reaches within the tolerable set...
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Reactive Power
What is mean by reactive power? How it is generated?
Sreebai
- Sep 21st, 2010
Reactive power is the power required to transmit the active power. The reactive power is like an envelop,that is used to send a letter. Without this we cant send the active power and it cant be too hi...
SURAJTHEGREAT
- Mar 3rd, 2009
We know reactance (hypothetical resistance) which reduce the supply voltage by opposite flowing induced emf. This power loss due to reactance is known as reactive power. This power is not useful power. It is a waste. However it is useful in determining the phase angle.
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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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Quality Factor
What is the importance of quality factor in resonance?
thakur.rajesh.ranjan
- Sep 27th, 2010
Sinusoidally driven resonators having high quality factor resonates with greater amplitudes but have a smaller range of frequencies around that frequency for which they resonates. Thus a high Q (quali...
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Induction Motor
In single phase induction motor, what is phase? what is induction? Why only this motor used in fans?
guntur.srikanth
- Sep 30th, 2010
Mainly the induction motor works with mutual induction principle that is why we are using them in fans
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Cable fault identification.
One 3.5C cable is connected in a feeder with the neutral is isolated in the two ends(3 phases connected and neutral open in both sides). Now on rear end the output voltage is getting reduced by 20V in two phases and 40v increased by another phase.(between phase and neutral but neutral in open in two ends).the cable is meggered and we got the value of 100Mega ohm. There is no load in rear end. Kindly...
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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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Phase Usage
Why and when we use single phase and three phase?
raviiisc
- Oct 31st, 2010
This is the most common question.Whenever we are dealing with large quantity of power we use the Three phase system rather than the single phase system. The cause is the cost of eqipment is more....
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Transformer
What happens to the power factor of a transformer when the input voltage exceeds the rated voltage? Will it increase or decrease? Give explanation.
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Power Lines Protection
Why the 1st zone of protection relay is 90% not 100%?
ashokumarrk
- Nov 14th, 2010
Zone-1 protection is 80% in (NTPC, POWER GRID, NPCIL, NHPC, BBMB....) bcz we have consider the errors in CT, PT and also the line length. Datas provided should be same as the actual, but it wont. In order to compensate all these Zone-1 protection is 80%
pradipsabar2009
- Jul 29th, 2010
If we consider the 100%, 100% in the sense there is another CB present there. so there is a dilemma which CB should operate first. Hence the first zone of protection is never 100%
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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
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Series Connection
If 100w & 50w bulb connect in series and if we supply 440v then what happen, which one glow first?
veerateja
- Dec 17th, 2010
The two bulbs will glow at a time bcoz the ckt should close the path through the second bulb also mean while the electricity(electron) speed is nearley equal to light speed.
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Is it possible for a feedback surge to travel over a wireless connection? Would the answer be different in a vacuum?
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Potential Transformers Applications
What are the applications of potential transformers other than metering and under voltage protection?
Raman Jain
- Dec 29th, 2010
There are numerous applications of Potential Transformers .1. For Metering Purpose.2. Required for Synchronisation of Feeders / Generator with Grid.3. For Feed back of AVR.4. Distance Protection of fe...
ripago
- Nov 28th, 2010
1. Over/Under Freq. Protection2. Syncrhonizing Generator to Grid.3. If you don't have spare of PMG then you can use this PT for AC Power supply to the excitation Unit of your own Genarator.
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Motor Vibration
What can be the possible causes of Vibration in HT motors?
Raman Jain
- Jan 2nd, 2011
Vibrations in HT Motors may be due to several reasons :1. Mis-alignment 2. Worn Bearing3. Loose foundation bolts.4. Unbalance rotor etc.
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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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Power Plant
What is the processing of power plant and what are the equipment used for coal handling power plant?
Raman Jain
- Jan 3rd, 2011
There are various equipments used in the Coal Handling Plants :1. Wagon Tipplers : to unload the coal wagons2. Stacker - Reclaimers : stack and reclaim the coal in/from stock yard.3. Conveyor Belts : ...
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DG Set Tripp
What will you do when D.G. set gets tripped?
Raman Jain
- Jan 3rd, 2011
First see at what indications D.G set get tripped. Find the cause and rectify . Than again start the DG set.
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