Contents - AP Technology

Basic electrical-engineering formulas
Cross-section and diameter calculation of flexible leads
A = lead cross-section in mm2 A = d
Z = lead diameter in mm
n = number of individual wires
Z = 1,34·n·d d = individual wire-Ø in mm
2 ·0,785·n
Conductor resistance
R =
G =
·L
1
R
S
L
R =
·S
=
Characteristic wave impedance
R = electrical resistance in
G = electrical conductivity in S
S = conductor cross-section in mm 2
L = length of conductor in m
= specific resistance (Rho)
= conductivity (Kappa)
Example given L = 800 m, R = 100 , S = 0,15 mm2 required = Conductivity
Calculation route L
=
R·S
Ohm's Law
I =
U
R
1
I = electrical current in A
U = electrical voltage in V
R = electrical resistance in
Example
U = 220 V ; R = 980
U 220 V
I = =
R 980
I = 0,22 A
L
Z =√
C
Z
L
=
=
characteristic wave impedance in
inductance in H
C = capacity in F
For coaxial cables r = dielectric constant
60
Z = In
r
Effective capacitance conductor/mass
C=
r ·10 3
D
d
18·ln D
d
800 m
=
100 ·0,15 mm2 = 53,3
m
·mm 2
ln = natural logarithm
D = Ø above dielectric
d = Ø of inner conductor
C = capacity in pF/m
r = dielectric constant
D = Ø above dielectric
d = Ø of inner conductor
ln = natural logarithm
Resistance/Temperature
Technical Guidelines
R W = R K (1+·) R K = cold resistance at +20°C in
R W = hot resistance in
R W = R K +R R = change in resistance in
= temperature changes in °C
R = ·R K · = temperature coefficient
=
R W -R K
R K ·
Installation in series of ...
Cu = 0,0039 1/°C
Alu = 0,00467 1/°C
Example
= 70 °C
R K = 100
= 0,0039 1/°C
R W = R K ·(1+·)
R W = 100 W(1+0,0039·70)
R W = 127,3
Resistors R g = R 1 + R 2 + R 3 + ...
Capacitors
1 1 1 1
+ + + ...
L g L 1 L 2 L 3
Inductances L g = L 1 + L 2 + L 3 + ...
Installation in parallel of ...
Resistors
Two Resistors
Capacitors C g = C 1 + C 2 + C 3 + ...
Inductances
Powers of ten
1 1 1 1
= + + + ...
R g R 1 R 2 R 3
R1 · R2 Rg =
R1 + R2 1 1 1 1
= + + + ...
L g L 1 L 2 L 3
10 12 Tera T 1 000 000 000 000
10 9 Giga G 1 000 000 000
10 6 Mega M 1 000 000
10 3 kilo k 1 000
10 2 hekto h 100
10 1 deka da 10
10 0 1
10 -1 dezi d 0,1
10 -2 centi c 0,01
10 -3 milli m 0,001
10 -6 mikro µ 0,000 001
10 -9 nano n 0,000 000 001
10 -12 piko p 0,000 000 000 001
16.085