Normal
0
false
false
false
EN-US
X-NONE
X-NONE
...
Saturday, February 28, 2015
Thursday, February 26, 2015
What is the difference between fuse and circuit breaker?
(i) Fuse performs both detection and interruption functions. Circuit breaker performs interruption function only. The detection of fault is made by relay system.
(ii) The breaking capacity of fuse is very small compare to that of circuit breaker.
(iii) The operating time of the fuse is smaller than operating time of CB.
(iv) After every operation, replacement is required in the fuse. In case of circuit breaker, replacement is not required.
...
Sunday, February 22, 2015
Comparison of PN junction diode and zener diode
Comparison of PN junction diode and zener diode
s.no
PN
junction diode
zener
diode
1
Symbol
Symbol
2.
Operated in forward biased condition
and never operated in reverse biased condition
Operated in reverse breakdown region
3
Characteristics lies in 1st quadrant
...
Friday, February 13, 2015
construction details of a dc machine
Construction details
of a dc machine
Parts of dc machine
•
Yoke
•
Pole
core and pole shoe
•
field
winding
•
Armature
core
•
Armature
winding
•
Commutator
•
Brushes
and...
Saturday, February 7, 2015
What is the necessity of starter in DC motor ?
What is the necessity of starter in DC motor ?
The voltage equation of dc motor is
V = Eb + IaRa
at start Eb = 0, V= IaRa
Ia = V / Ra. (Ra alone limits the Ia)
generally motor is switched on with normal voltage and Ra is very small, the Ia at start is very high.This will blow out the fuses and may cause permanent mechanical damage to the motor.To limit this starting current to a safe value a variable resistance is connected in series with armature.This resistance is called as starter.
...
