D. C. Circuits - Bright Classes

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7 Οκτ 2013 (πριν από 4 χρόνια και 1 μήνα)

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50
.
1





Basic Circuit Concept

V =
, Power dissipated in a resistor,

Power dissipated in a resistor:
.Capacitance:
c

=

Current


voltage relationship in a capacitor:

Ohm’s Law: V = R.I, Series circuit: = R
1
.I+R
2
.I, Parallel Circuit: I=

Kirchhoff’s current Law: I
1
+I
3
+I
5
=I
2
+I
4,


D. C. Circuits

Delta to
Star

Star to Delta



Rc =

A.

C. Circuit

Average value and rms value Kp =



Series resonance:


Chapter

50


Basic Electrical and Electronics (BEE)


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.
2



Parallel resonance:

Three


Phase Circuits


Star Connection

Delta Connection

V
L
=

I
L
= I
ph

I
L

=
Iph



S = 3

Two


wattmeter method

For lagging power factor

For leading power factor

Single


phase Transformer







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.
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Where W
i

and W cu are in kW. and

Condition for maximum efficiency, W
i

= Wcu

Load kVA (maximum efficiency) = Full


load kVA






Electrical Machines

Where A = P for lap
winding A= 2 for wave winding

Generators

Shunt Generator

Series Generator

Compound Generator


Short shunt

Long shunt


I
a
= I
L
+I
f

I
f
=

E
g

= V+ I
a
R
a



Ia = Is = I
L



E
g

= V+ I
a
(R
a
+R
s
)

I
s
=I
f

I
a
=I
L
+I
f


E
g

= V+ I
a
R
a
+I
L
R
s


I
a
=I
L
+I
f


E
g

= V+ I
a
(R
a
+R
s
)

Motors


Shunt Motor

Series Motor

Compound Motor


Short shunt

Long shunt

BRIGHT ENGINEERING CLASSES

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.
4



I
a
= I
L
-
I
f


E
b

= V
-

I
a
R
a


I
f
=


Ia = Is = I
L



E
b

= V
-

I
a
(R
a
+R
s
)

I
s
=I
f

I
a
=I
L
-
I
f


E
b

= V
-

I
a
R
a
-

I
L
R
s


I
a
=I
L
+I
f


E
b

= V
-

I
a
(R
a
+R
s
)

Semiconductor Devices and Rectifiers

Bipolar Junction Transistors(BJT)





I
E
=I
B
+I
C

I
C
=

I
E
+I
CBO

I
C
=

I
B
+(1+

)I
CBO


Rectifiers

Half Wave Rectifier

Full Wave Rectifier

Current Tapped

Bridge

1.


I
dc





2.


I
rms
(I
ac
)




3.


I
m




4.


V
dc




5.


V
dc


(no load)




6.


P
dc




7.


P
ac




8.







9.


r




BRIGHT ENGINEERING CLASSES

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.
5


10.


PIV

Vm

2Vm

Vm

11.


% Regulation




Capacitor Filter

1.


2.

Electrical Engineering


AC
Fundamentals



Unless specified given or desired voltages & currents are in RMS.



Unless specified given or desired Power is Average or Active Power.



RMS value for a sine wave is =



Average value for a sine wave is
=



Inductive Reactance, X
L

=




Capacitive Reactance, X
c

=



Power factor, cos

=

=
Impedance, Z =
=



AC circuit containing Resistance only, v = V
m

sinωt
and i = I
m

sinωt,
V = I × R

P = V× I



AC circuit containing Inductance only, v = V
m

sinωt and i = I
m

sin(ωt
-

π/2)

V = I × X
L
;
P = 0



AC circui
t containing Capacitance only, v = V
m

sinωt and i = I
m

sin(ωt + π/2)

V = I × X
C
;

P = 0



AC circuit containing Resistance & Inductance only, v = V
m

sinωt and


i = I
m

sin (ωt
-
)
;
Z =

& V =
V = I × Z; P = V×I×cos
Current lags applied Voltage; hence, circuit as well as power factor is lagging.



AC circuit containing Resistance & Capacitance only, v = V
m

sinωt and

i = I
m

sin (ωt +

);
Z =

& V =
V = I × Z
;
P = V×I×cos
Current leads applied Voltage; hence, circuit as well as power factor is leading.




AC circuit containing Resistance, Inductance & Capacitance only, v = V
m

sinωt a
nd

i = I
m

sin (ωt ±
)
;
Z =
& V =

V = I × Z; P = V×I×cos
;
Phase

angle between Current & applied Voltage depends
on value of R, L &

C; hence, power factor can be unity, lagging or leading.