The Capacitor
BASIC CAPACITOR FORMULAS
I. Capacitance (farads)
XI. Equivalent Series Resistance (ohms)
.224 K A
E.S.R. = (D.F.) (Xc) = (D.F.) / (2 π fC)
English: C =
TD
XII. Power Loss (watts)
.0884 K A
Power Loss = (2 π fCV2) (D.F.)
Metric: C =
TD
XIII. KVA (Kilowatts)
II. Energy stored in capacitors (Joules, watt - sec)
KVA = 2 π fCV2 x 10 -3
1
E = ⁄
2
CV2
XIV. Temperature Characteristic (ppm/°C)
III. Linear charge of a capacitor (Amperes)
T.C. =
x 106
Ct – C25
dV
I = C
C25 (Tt – 25)
dt
XV. Cap Drift (%)
IV. Total Impedance of a capacitor (ohms)
C1 – C2
C1
2
2
Z = ͱ
RS + (X - X
)
L
C.D. =
x 100
C
V. Capacitive Reactance (ohms)
XVI. Reliability of Ceramic Capacitors
1
x
=
L0
Lt
Vt
Vo
X
Tt
To
Y
c
2 π fC
=
( ) ( )
VI. Inductive Reactance (ohms)
XVII. Capacitors in Series (current the same)
xL = 2 π fL
Any Number:
1
C
1
1
C2
1
---
=
+
VII. Phase Angles:
C1
C
N
T
Ideal Capacitors: Current leads voltage 90°
Ideal Inductors: Current lags voltage 90°
Ideal Resistors: Current in phase with voltage
C1 C2
Two: C
=
T
C1 + C2
XVIII. Capacitors in Parallel (voltage the same)
= C1 + C2 --- + C
VIII. Dissipation Factor (%)
C
T
N
E.S.R.
D.F.= tan ␦ (loss angle) =
= (2 πfC) (E.S.R.)
X
XIX. Aging Rate
c
IX. Power Factor (%)
A.R. = %D C/decade of time
P.F. = Sine ␦ (loss angle) = Cos (phase angle)
P.F. = (when less than 10%) = DF
f
XX. Decibels
db = 20 log
V1
V2
X. Quality Factor (dimensionless)
1
D.F.
Q = Cotan ␦ (loss angle) =
METRIC PREFIXES SYMBOLS
X 10-12
X 10-9
X 10-6
X 10-3
X 10-1
X 10+1
X 10+3
X 10+6
X 10+9
X 10+12
K
A
= Dielectric Constant
= Area
f
= frequency
= Inductance
= Loss angle
= Phase angle
Lt
= Test life
Pico
Nano
Micro
Milli
Deci
Deca
Kilo
Mega
Giga
Tera
L
␦
Vt
Vo
Tt
= Test voltage
TD = Dielectric thickness
= Operating voltage
= Test temperature
= Operating temperature
V
t
= Voltage
f
= time
X & Y = exponent effect of voltage and temp.
To
R
= Series Resistance
Lo
= Operating life
s
9
KYOCERA AVX [ KYOCERA AVX ]
