2
I. Capacitance (farads)
English: C =
.224 K A
T
D
Metric: C =
.0884 K A
T
D
II. Energy stored in capacitors (Joules, watt - sec)
E =
1
⁄2 CV
2
III. Linear charge of a capacitor (Amperes)
I = C
dV
dt
IV. Total Impedance of a capacitor (ohms)
Z = R
2
S
+ (X
C
- X
L
)
2
V. Capacitive Reactance (ohms)
x
c
=
1
2 π fC
VI. Inductive Reactance (ohms)
x
L
= 2 π fL
VII. Phase Angles:
Ideal Capacitors: Current leads voltage 90°
Ideal Inductors: Current lags voltage 90°
Ideal Resistors: Current in phase with voltage
VIII. Dissipation Factor (%)
D.F.= tan ␦ (loss angle) =
E.S.R.
= (2 πfC) (E.S.R.)
X
c
IX. Power Factor (%)
P.F. = Sine ␦ (loss angle) = Cos
f
(phase angle)
P.F. = (when less than 10%) = DF
X. Quality Factor (dimensionless)
Q = Cotan ␦ (loss angle) =
1
D.F.
XI. Equivalent Series Resistance (ohms)
E.S.R. = (D.F.) (Xc) = (D.F.) / (2 π fC)
XII. Power Loss (watts)
Power Loss = (2 π fCV
2
) (D.F.)
XIII. KVA (Kilowatts)
KVA = 2 π fCV
2
x 10
-3
XIV. Temperature Characteristic (ppm/°C)
T.C. =
Ct – C
25
x 10
6
C
25
(T
t
– 25)
XV. Cap Drift (%)
C.D. =
C
1
– C
2
x 100
C
1
XVI. Reliability of Ceramic Capacitors
L
0
=
V
t
XT
t
Y
L
t
(
V
o
)(
T
o
)
XVII. Capacitors in Series (current the same)
Any Number: 1
=
1
+
1
---
1
C
T
C
1
C
2
C
N
C
1
C
2
Two: C
T
=
C
1
+ C
2
XVIII. Capacitors in Parallel (voltage the same)
C
T
= C
1
+ C
2
--- + C
N
XIX. Aging Rate
A.R. = %
D
C/decade of time
XX. Decibels
db = 20 log
V
1
V
2
Pico X 10
-12
Nano X 10
-9
Micro X 10
-6
Milli X 10
-3
Deci X 10
-1
Deca X 10
+1
Kilo X 10
+3
Mega X 10
+6
Giga X 10
+9
Tera X 10
+12
K = Dielectric Constant f = frequency L
t
= Test life
A = Area L = Inductance V
t
= Test voltage
T
D
= Dielectric thickness ␦ = Loss angle V
o
= Operating voltage
V = Voltage
f
= Phase angle T
t
= Test temperature
t = time X & Y = exponent effect of voltage and temp. T
o
= Operating temperature
R
s
= Series Resistance L
o
= Operating life
METRIC PREFIXES SYMBOLS
Basic Capacitor Formulas
