Answer / virendra ku mallah

Grafite For Lubrication Carbon for current collection
purpose.

Answer / sahil joseph

According to the periodic table carbon lies in the list of
semiconductor having valency of 4 thus semiconductors have
the property that with increase in temp. their resistance
decreases. Thus when carbon brushes rub against the commutator
due to friction their temp. increases and resistance falls.
Thus they are used for collection of current in DC machines.
In AC systems slip rings are used.

Answer / karthik raman.b

it has good peripheral speed and current density, self lubricating

Answer / prasad

THE PURPOSE OF CARBON BRUSHES ARE TO POLISHING THE SURFACE
OF THE COMMUTATOR AND TO REDUCE THE REACTENCE AT THE
COMMUTATOR.

Answer / guest

carbon is hard material compared to graphiate so it will
give a stainsail strength of graphite at the time of full
load runing condition.and graphite use for the just collect
the current and passing.

Answer / vinod kumar t

this wil reduce th sparking in the commutator

what sq.mm copper pvc wire need for ac load current 25amps for 230v ?

4 Answers   Khadamat, Siemens,

Why do you use an isolator on both sides of the circuit breaker? ( shortly answer)

2 Answers  

i am using star-delta connections with reverse/forward direction motion of the 75hp induction motor.What should be the ratings of Main,Delta and Star contactors and why?

1 Answers  

RESISTONS R1 AND R2 in parallel = Total R.? 1-R=R1+R2 2-R=1/R1 + 1/R2 3-1/R + R1+R2 R=R1R2/R1+R2 select one

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how to claculate earth strip size for 1500kVA transformer for neutral and body

4 Answers  

Briefing the effects of ASR and ACR of a double closed-loop speed regulating system.

0 Answers  

what is the difference between oil surge relay and buchholz relay.

0 Answers   MPPEB, Suparco,

if negative of DC supply used and positive is grounded through EGB, and if ELCB used in the system then is it sense the positive volatge and get tripped is it possible?

0 Answers   Delta,

Among the following Which is vector quantity? a. Flux b. permitivity c. flux density d. magnetic intensity

2 Answers  

what is the use of neutral?

14 Answers   IOCL,

why ups in kva ratings?

2 Answers  

draw the block diagram of fire alarm?

0 Answers