why the efficiency of the dc machine is high ,when it is
operated as a generator?
Answers were Sorted based on User's Feedback
Answer / guest
Effiiency of any machine is defined as the ratio of output
to the output.
Efficiency=(O/P)/(I/P)
MATHEMATICAL PROOF
Since electrical quantities are easier to measure in
comparison to mechanical quantities.
So in the determination of efficiency of DC machines,
we first find electrical quantities(input or output)and
subsequently find mechanical quantities(output or input)by
subtracting or adding the losses.
Efficiency of Generator=Output/input=(V*I)/(V*I+loss)
Efficiency of Motor = Output/input=(V*I-loss)/(V*I)
As long as machine is same, the rating and losses are not
going to change.
Clearly the ratio of above two equation is greater than 1
meaning there by efficiency of generator is greater than
motor.
PHYSICAL CIRCUIT PROOF
If we look into the circuit model,In case of generator back
emf causes less amount of current to flow through the
armature.So electrical losses(Cu loss) are less.Electrical
losses are function of current
In case of motor counter torque is produced so speed of
motor is less.So rotatinal loss(Core and friction) is
less.Rotational losses are function of speed.
Since loss:electrical loss > Mechanical loss.
So efficiency:Generator > Motor
Author:arbelectbit@yahoo.com
| Is This Answer Correct ? | 3 Yes | 0 No |
Answer / iamdon
Sorry for typing mistake....
Please read LAST WORD of first line as INPUT insted of
output.
Author:arbelectbit@yahoo.com
| Is This Answer Correct ? | 2 Yes | 0 No |
Answer / simon
Genrator can become motor but a motor cannot become Gen.
| Is This Answer Correct ? | 0 Yes | 0 No |
What would cause a 240v choke that should give 110v out on a 16w lamp to gradually increase to 160v?
Electromagnetic torque developed by the motor is compared to shaft torque. A less B same C depends on motor design D more
Why Stabilising Resistor used in REF circuit ?
how to calculate cable bending angle in a trench?
does any one know where we can purchase insulation oil for high voltage oil filled cables
why eee branch?
How many safety of Disel Generator
what is difference between neutral& grounding?
What are thermo couple cables and where they are used.
What happen if we give resistance to the armatuure of a dc motor?a
How you calculating the current for a 2.5 Sqmm cable. A 30 Hp 3 phase AC motor of power what size of cable is used for this motor.
Hello to all, Please someone can send me HPCL ELECTRICAL Engg. Sample papers to me? Its urjent....my email address is.... raviasiapacific@gmail.com
Civil Engineering (5086)
Mechanical Engineering (4456)
Electrical Engineering (16639)
Electronics Communications (3918)
Chemical Engineering (1095)
Aeronautical Engineering (239)
Bio Engineering (96)
Metallurgy (361)
Industrial Engineering (259)
Instrumentation (3014)
Automobile Engineering (332)
Mechatronics Engineering (97)
Marine Engineering (124)
Power Plant Engineering (172)
Textile Engineering (575)
Production Engineering (25)
Satellite Systems Engineering (106)
Engineering AllOther (1379)