Interested to Buy Any Domain ? << Click Here >> for more details...
why the efficiency of the dc machine is high ,when it is
operated as a generator?
- 3 Answers
- 6664 Views
- I also Faced
- E-Mail Answers
Answer Posted / 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 |
Post New Answer View All Answers
Which of the following alternatives will be cheaper (1) A 100 h.p AC, 3-phase motor (2) Four motors of 25 h.p each (3) Five motors of 20 h.p each (4) 10 motors of 10 h.p each explain
Would you recommend to replace all oil filled cables with xlpe cable for hv transmission with the current technolgy for xlpe cable?
how to calculate kvar in Akiva
what is the difference between STAR and DELTA connection and application wise how it can be utilizedd
How CFL &T5 tube light glows?
FOR 16/20 MVA 132/33 KV ONAN/ONAF TYPE TRANSFORMER IT IS DESIGNED FOR 16 MVA WITH ONAN CONDITION.IT BECOMES 20 MVA UNDER ONAF CONDITION.LOAD LOSS IS GUARANTEED FOR 65KW AT 20 MVA AND % IMPEDANCE 13.75. PLEASE TELL US AT WHAT LOAD LOSS AND % IMPEDANCE IT SHOULD BE DESIGNED FOR 16 MVA AND WHAT WILL BE ITS EFFICIENCY AT 20 MVA?
What is a differential amplifier? Also, explain cmrr.
HELLO SIR, IAM PREPARING HPCL EXAMS. SO PLS SEND MATERIAL OF HPCL ELECTRICAL ENG..TO VIJAY_8888@YMAIL.COM
What is center gravity load in substation?
How to confirm the Phase shifting Transformer VECTOR GROUP relation , as below ZNy11.45d10.45-ZNYy0.15d11.15
How to do cable sizing calculation for 750 A Neutral Earthing resistor for 33kv. the 33kv cable going to swbd. is 630mm2 3 runs.
Sir, plz tell me how droop setting is done in parellel operation od DG set ? please give practical example ?
An automatic water heater is an example of which type of control system?
what is the voltage between earth & neutral in 3 phase electrical connection.
. How to calculate the Short Circuit Impedance in Transformer? How to calculate the Short Circuit Impedance in Transformer?
