EMECH_BO_Y2 Electrical and Electronic Technology II
Exam attachment A
Formula sheet
Kilowatts / Horsepower:
1kW = 1.34 HP
1 HP = 746.3 Watts
R.P.M. x Lbin
HP = -----------------63000
D.C.
DC current I = , Amps
Power
P = V x I, Watts, or
Voltage
V = I x R , Volts,
A. C.
A.C. Current
I =
Impedance Z =
√
V
I R
or
I =
, Amps
P
I V
P = I2R, Watts,
or
or
P =
, Watts.
, Volts.
V=
V
Z
Ω
Reactance X = Xc - XL
or
Capacitive Reactance XC =
1
C
or
Inductive Reactance XL = ωL
or
2πfL
Apparent power
or
or I2Z ,
= VxI
True power
P = I 2R
Power factor
Pf
=
XL - Xc Ω
or
Truepower
Apparentpower
1 of 2
Ω
Watts
or
R
Z
Ω
V/A
EMECH_BO_Y2 Electrical and Electronic Technology II
Three phase A.C.
For Star connected 3Φ:Line voltage = phase voltage x √3
Line current = phase current.
_________
Neutral Current = √ IH2 + IV2
IH = Iy cos 30˚ - IB cos 30˚
IV = IR - IY cos 60˚ - IB cos 60˚
(1.73)
For Delta (mesh) Connected 3Φ:Line current = Phase current x √3 (1.73)
Line voltage = phase voltage
Logic and Electronics:
De Morgan’s Theorem
1
2
Transistor
_____
X+Y
____
X.Y
=
=
__ __
X .Y
__ __
X +Y
Common emitter voltage gain
=
Common emitter power gain
= hfe2 x
Operational Amplifier :
( Inverting amplifier) Voltage gain Av =
(non-inverting amplifier) Voltage gain Av =
2 of 2
hfe x