Follow Our FB Page << CircleMedia.in >> for Daily Laughter. We Post Funny, Viral, Comedy Videos, Memes, Vines...


why generator and t/f ratings given in kva & motor rating
is in KW?

Answers were Sorted based on User's Feedback



why generator and t/f ratings given in kva & motor rating is in KW? ..

Answer / karthik

Watt is the product of voltage, current and power factor.
VA is the product of voltage, current and power factor.

Motor is an inductive load and operates at a power factor
less than unity. So the current drawn by it is more than the
apparent at constant power.
For a 3ph motor, P=&#8730;3*V*I*cosø where V,&#8730;3 are constants.
At constant P, I*cosø is also a constant. if pf cosø
varies, I too varies. i.e. if pf is poor (cosø reduces), I
increases. Hence rating needs to be specified in KW.

Whereas for a generator, it isn't a load. It supplies power
to a load. So power factor doesn't come into picture. Hence
its rating is specified in KVA.

Is This Answer Correct ?    11 Yes 2 No

why generator and t/f ratings given in kva & motor rating is in KW? ..

Answer / shahulsnfa

See, KVA is apparent power which means the power
available. and KW is real power which means how much power
utilised from available power.

motors are utility machines which consumes the power
from the source for its working. and the generator are
producers and not consumers. the motor consumes the power
in terms of voltage and current.

when phase angle difference btwn current and voltage
is zero, then KW=KVA. but the phase angle difference
between current and voltage will have some value regarding
load. so the real power is determined by the load and not
by the source.

that is why macines are rated in KW and generators are
in KVA. and the transformers are transforming power rather
than consuming.. so they also rated in KVA.

Is This Answer Correct ?    11 Yes 2 No

why generator and t/f ratings given in kva & motor rating is in KW? ..

Answer / navmit bhimani

In transformer there are two losses,copper loss depend on
current and iron loss depend on voltege and nothing
relation with power factor.so and so....

Is This Answer Correct ?    8 Yes 1 No

why generator and t/f ratings given in kva & motor rating is in KW? ..

Answer / vinamra

generator and the transformer is not a load,means its power
fector is not decided,its pf is depend upon the loads which
will connect to the gen. or trans.,therefore it rating is
in kva.but in case of motor its power fector is predecided
so its rating is in kw

Is This Answer Correct ?    4 Yes 0 No

why generator and t/f ratings given in kva & motor rating is in KW? ..

Answer / pillay

We buy/fix a motor to do a specific job.Job done is measured in watts.So a machine say a pump will use up to 3 KW to run as designed than we fix a motor of 3KW or slightly bigger to run it.Now the motor is 3KW or bigger say 30 KW and the voltage is AC or DC operated is up to you.

generators are rated in KVA because we dont know at what pf will it be operated. Say you have fitted a pf correction board to maintain at 0.95pf, you dont have a guarantee it wont breakdown or take some time to adjust. What is important the generator voltage is constant and the generator dont trip or burn.So if the pf can change anytime the current also can change anytime this may make your generator to trip on overcurrent,overvoltage(leading pf)or even destroy your genset.By rating your generator by KVA with a constant designed voltage you can know the maximum current the genset can give irrespective of pf.It is a safer and sure way of protecting your generator.you can even load yor genset at 0.2 pf so long you dont exceed the rated amps or KVA.

Is This Answer Correct ?    1 Yes 0 No

why generator and t/f ratings given in kva & motor rating is in KW? ..

Answer / expert

when kva is calculated pf comes into play, and not in KW.
as we know that the tranf and DG pf is dependent on the
load,but the motor draws an constant power with specified
pf..........if not clear plz reply

Is This Answer Correct ?    4 Yes 11 No

Post New Answer



More Electrical Engineering Interview Questions

are induction motor have poles? yes / no , why?

3 Answers  


what is self capacitance of inductor

0 Answers   Bhel,


ht side line to earth voltage

0 Answers   JLL,


How to calculate capacitor bank value to maintain unity power factor with some suitable example?

0 Answers  


what are the settings is there for ABB REM543 Generator Protection Relay

1 Answers  






What is effect of low pf on HT supply.

6 Answers  


What are the classifications of heating element?

0 Answers   BARC,


A circuit breaker on detecting fault will a. Open b. Close c. Open and trigger the alarm

2 Answers  


After synchronization with grid what is the demand value QKVAR and how we will maintain that?

0 Answers  


Dear all, how we select the cable size according  to current with or without including different correction factor , is there any direct method for sizing of cable... 

0 Answers   Kharafi National,


How to megger test 11 kV cable and the acceptance IR value

0 Answers   BVG, NFL, ONGC,


Why electricity in India is in the multiples of 11 like 11kv, 22kv, 33kv

2 Answers   KPIT,






Categories
  • Civil Engineering Interview Questions Civil Engineering (5076)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4445)
  • Electrical Engineering Interview Questions Electrical Engineering (16606)
  • Electronics Communications Interview Questions Electronics Communications (3915)
  • Chemical Engineering Interview Questions Chemical Engineering (1092)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (214)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (258)
  • Instrumentation Interview Questions Instrumentation (2992)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (97)
  • Marine Engineering Interview Questions Marine Engineering (123)
  • Power Plant Engineering Interview Questions Power Plant Engineering (172)
  • Textile Engineering Interview Questions Textile Engineering (575)
  • Production Engineering Interview Questions Production Engineering (0)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1378)