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Statements or suggestions concerning possible use of our products are made without representation or warranty that any such use is free of patent infringement
and are not recommendations to infringe any patent. The user should not assume that all safety measures are indicated or that other measures may not be
required. Specifications are typical and may not apply to all applications.
TPC
1
Introduction
High Voltage Ceramic Capacitors
HIGH VOLTAGE CERAMIC CAPACITORS
are particularly
suitable for applications requiring a high voltage (from 10
to 150 kV), while reactive current remains low. Ceramic
capacitors also achieve very good performance under pulse
and discharge conditions.
Various disc types cover a wide range of capacitances and
voltages as shown in the following figure. Specific properties
depend on the dielectric material used.
Other configurations such as rods (HF type), cascades (HC
type) are used to meet specific applications.
Voltage (kV)
50
40
HP
30
20
HT
HD HR
HZ
10
10
100
1000
10000
Capacitance (pF)
2
TPC
Introduction
General Characteristics
The real characteristics of a capacitor can be described
using conventional physical parameters and the following
equivalent electrical circuit:
Rp
C
Rs
Cp
Ls
ƒ
w
Z
C
K
A
t
T.C.
DC/C
V
R
V
DC
V
RMS
V
P
V
E
R
P
IR
R
S
L
S
C
P
j
tg
d
DF
Q
capacitance is a measure of the capacitors aptitude
to store electrical charges Q under a voltage V
(C = Q/V).
the dielectric constant, specific to each material
(less than 500 for type I materials, from 1000 up to
10,000 for type II materials),
the area of the electrodes, and
the thickness of the dielectric layer are the parame-
ters determining the capacitor value
A
C=K
(K =
r
)
t
the temperature coefficient of the capacitance is
expressed in ppm/°C for stable type I dielectrics.
is used for type II dielectrics and is expressed in %
of change of the capacitance in a fixed temperature
range.
the rated voltage is the maximum voltage that can
be applied to the capacitor on continuous opera-
tion. It can be constituted by:
a direct current component
an alternating current component
the peak voltage
the test voltage
the parallel resistance
the insulation resistance under V
DC.
or ESR (Equivalent Series Resistance) accounts for
the conductivity of the electrodes and connections.
or ESL (Equivalent Series Inductance) depends on
the geometry of electrodes dielectric and connec-
tions, leads...
takes into account dielectric environment of the
capacitor (coating...) but is generally neglected
except to describe very high frequency behavior of
the capacitor or for very low capacitance value.
Rp, Rs, Ls, Cp can be considered as parasitic
effects. They generate energy losses and a
dephasing
difference between voltage and current from 90°.
The loss angle
d
(90° -
j)
is commonly used.
the tangent of loss angle
the dissipation factor (same as tg
d)
the quality factor is the ratio between the stored
energy and the dissipated energy. It measures the
quality of the capacitor and can be expressed as
Q = 1/tg
d
or 1/
D.F.
being the frequency of the AC signal
the pulsation of this signal with
w
= 2pƒ
the complex impedance of the capacitor is given by
the relation (neglecting Cp):
1
=R+jX
Z = R
S
+ j L
S
w
+
1
+ j Cw
R
P
the tangent of the loss angle tg
d
can also be
R
expressed as tg
d
=
X
1
so, neglecting Ls for
L
S
w
<
C
w
1
+
1
tg
d
= R
S
Cw +
2
Cw
R
P
R
P
Cw
e
ƒ
RS
the series resonance frequency of the capacitor is
the frequency where the capacitance reactance is
exactly equal to the inductive reactance due to L
S
1
1
1
L
S
w
=
or
w
=
or ƒ
RS
=
2p L
S
C
Cw
L
S
C
the parallel resonance frequency occurs when L
S
is
ƒ
RP
1
equal to C
P
:
ƒ
RP
=
2p L
S
C
P
Between ƒ
RS
and ƒ
RP
, the capacitor reacts as an
inductance, but still blocks DC.
The equivalent electrical circuit can be simplified
using approximations according to the frequency:
- At ƒ = ƒ
RS
the circuit is reduced to
Z = R
S
Rs
- For high frequencies but below ƒ
RS
C
Rs
Z (W)
Z = R
S
+1/jCw
tg
d
= R
S
Cw
Rs
- For low frequencies Z =
R
P
1
1 + jCw
R
P
1
R
P
C
w
F(Hz)
F rs
C
tg
d
=
I
RMS
W
R
W
A
is the maximum RMS current that can be transmit-
ted by the capacitor electrodes
is defined as the maximum reactive power and is
I
2
RMS
2
expressed by W
R
= V
RMS
Cw =
Cw
is the active power or dissipated power
W
A
= W
R
tg
d
= (2pƒCV
2
)(DF)
TPC
3
Introduction
Dielectrics - Type I - Temperature Compensating
TYPE I CAPACITORS - GENERAL
(with specific temperature coefficient)
DIELECTRIC SELECTION -
STANDARDIZATION
(
Temp. coeff.*
= -55 +125°C)
Tolerance**
(ppm/°C)
Specification Code
TPC
CECC
CEI
MIL
AG / 1B
CG / 1B
HG / 1B
PG / 1B
TJ / 1B
UJ / 1B
VK / 1B
DIN
EIA
Type I capacitors are particularly suitable for applications
where high stability of capacitance and low losses are
required (tuning circuit capacitors). In addition, they offer
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