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Application Guide Film Capacitors
CDE Cornell Dubilier 1605 E. Rodney French Blvd. New Bedford, MA 02744 Phone: (508)996-8561 Fax: (508)996-3830 www.cde.com
Application Guide
Film Capacitors
Polypropylene Typical Characteristics at 1 kHz
Polyester Typical Characteristics at 1 kHz
Polyphenylene Sulde Typical Characteristics at 1 kHz
Degrees Centigrade
Degrees Centigrade
Degrees Centigrade
Degrees Centigrade
Degrees Centigrade
Degrees Centigrade
% Capacitance Change
% Capacitance Change
% Capacitance Change
Megohms x µF
Megohms x µF
Megohms x µF
Capacitance Change vs. Temperature Insulation Resistance vs. Temperature CDE Cornell Dubilier 1605 E. Rodney French Blvd. New Bedford, MA 02744 Phone: (508)996-8561 Fax: (508)996-3830 www.cde.com
Application Guide
Film Capacitors
Dissipation Factor vs. Temperature Dissipation Factor vs. Frequency
Polyester Typical Characteristics
Polypropylene Typical Characteristics
Polyphenylene Sulde Typical Characteristics
% Dissipation Factor
% Dissipation Factor
Dissipation Factor
Dissipation Factor
Dissipation Factor
Dissipation Factor
Degrees Centigrade
Degrees Centigrade
Degrees Centigrade
Frequency
Frequency
Frequency CDE Cornell Dubilier 1605 E. Rodney French Blvd. New Bedford, MA 02744 Phone: (508)996-8561 Fax: (508)996-3830 www.cde.com
Capacitance is within tolerance
when measured at 1 kHz ±20
Hz (120 Hz for polyester if C >1
µF) and 25 ºC ±5 °C. Standard
tolerance is ±10%.
Dissipation Factor or tan is
the ratio of the capacitors ESR
to its reactance. Its no more than
specied when measured at 1 kHz
±20 Hz (120 Hz for polyester if
C>1 µF) and 25 ±5 °C.
Insulation Resistance changes
from a minimum resistance
capacitance product (M
µF)
to a minimum resistance (M
)
for rated capacitances above
0.25 to 0.5 µF, depending on the
capacitor type. It is no less than
the lesser of the RC product or
the R specied, when measured
at 100 Vdc after 2 minutes and at
25 ±5 °C.
Rated Voltage is the maximum
continuous voltage for actual
use up to the rated maximum
operating temperature.
Dielectric Strength is the
maximum peak voltage that the
capacitor is rated to withstand
at room temperature. Test by
applying the specied multiple
of rated voltage for one minute
through a current limiting
resistance of 100
per volt. As
an illustration, to test a Type DPM
capacitor rated 250 Vdc and 175%
dielectric strength, apply
438
Vdc
through a 43.8 k

or higher value
resistor.
Life Test: Subject capacitors to
rated maximum temperature ±3
°C with the specied multiple of
rated voltage applied for 500 or
1,000 (+72, -2) hours as specied.
There will be no visual damage
and the capacitance will not
have changed more than ±5%.
Insulation resistance will not
decrease to less than 50% of
initial limit. Dissipation factor
will not increase to more than
initial limit.
Pulse Capability is peak-current
Capability. The ability of the
capacitor to withstand current
transients is set largely by the
integrity of the lead connections
and is indicated by the dV/dt
rating, the maximum permitted
rate of change of voltage in V/µs.
The peak current rating in amps is
the rated capacitance in µF times
the dV/dt rating:
Ipk = C(dV/dt)
Marking includes part number,
capacitance in µF, tolerance in %,
manufacturer and rated voltage
in Vdc and Vac. Small units
may include only Type, CD,
capacitance in pF and a tolerance
code. Example: DLMCD and
682K means Type DLM, 6800
pF (2 is the number of zeroes)
and 10%.
When used, tolerance codes are:
F = ± 1%
G = ± 2%
H = ± 6%
I = ± 3%
J = ± 5%
K = ±10%
M = ±20%
M e t a l l i z e d v s . F i l m / Fo i l
Construction. Heres how to
choose. For a metallized film
capacitor, the capacitor plates
are aluminum sprayed onto the
dielectric lm by thin-lm vacuum
deposition. Compared to making
the capacitor with separate foil and
lm sheets, metallizing enables
smaller size, lighter weight, lower
cost per microfarad and self-
healing, but it also engenders
lower current capability. Smaller
size and cost is especially striking
in high capacitance ratings.
Self healing refers to an internal
short circuit from an overvoltage
transient or a fault in the film
which clears in microseconds
by vaporizing the aluminum
metallizing at the fault site. There
is a glitch in the applied voltage, but
the capacitor suffers no permanent
damage save a negligible reduction
in capacitance. The advantages
make CDE metallized film
capacitors the correct high-value
Application Guide
Film Capacitors CDE Cornell Dubilier 1605 E. Rodney French Blvd. New Bedford, MA 02744 Phone: (508)996-8561 Fax: (508)996-3830 www.cde.com
choice for all applications except
four:

low capacitance, less than
.01 µF, where size difference is
not signicant and the lm/foil
material cost is less,

high continuous current as in a
resonant circuit,

high-transient current as in a
snubber circuit, and

low noise where self clearing is
a problem with its attendant, albeit
rare, volts of noise.
Polyester Dielectric: Just as
metallized is usually the CDE
construction of choice, so too,
polyester is usually the dielectric
lm material of choice. Of the
three CDE dielectrics, polyester
has the highest dielectric constant
and delivers the lowest cost,
smallest size capacitors with the
bonus of being able to operate
to 125 °C at half rated voltage.
However, with a DF hovering at
1% at higher temperatures, power
dissipation prevents its choice for
high current or high-frequency
AC voltage applications, and with
about a 5% capacitance change
from 55 °C to 0 °C and from
50 °C to 125 °C, polyester is not the
choice for precision capacitance at
temperature extremes. But notice
that capacitance changes only
±1% from 0 °C to 50 °C.
Polypropylene Dielectric with its
low dissipation factor empowers
CDE capacitors for high-current
DC, high-voltage AC and high-
frequency AC applications. And
its high insulation resistance and
low dielectric absorption are a
t for precision DC capacitors.
It would displace polyester
in many applications except
its low dielectric constant and
unavailability of thin-gauge lms
produces larger case sizes and
prices. A slight handicap its
maximum operating temperature
is 105 °C.
Polypropylene ts many of the
applications polyester misses. It
even complements polyester in
wide temperature applications:
capacitance decreases with
temperature at about the same
rate as capacitance increases
for polyester capacitors, so
a polypropylene capacitor in
parallel with a polyester spawns
a temperature-compensated
capacitor.
Polyphenylene Sulfide is for
precision capacitance and wide
temperature applications. Able to
operate from 55 °C to 125 °C and
hold capacitance change to less
than 1% over all but the extremes
of the range, polyphenylene sulde
is the preferred precision-capacitor
dielectric and is the dielectric lm
in FCP chip capacitors.

AC Voltage Operation:
You can use all CDE film
capacitors with either AC or DC
voltages or a combination of the
two. The rules for successful
application are: 1) dont exceed
the dielectrics voltage capability;
2) keep the capacitor cool, and 3)
dont operate with corona. As a
practical matter, heres how you
do those three rules.
Limit the voltage peaks to the rated
DC voltage. Limit the current
peaks to the rated capacitance
times the dV/dt rating. For high-
frequency operation limit the
power dissipated so that the case-
temperature rise is no more than
15 °C and at high temperatures
the case temperature no greater
than the maximum operating
temperature. The maximum high
frequency sine wave voltage for
a 15 °C rise may be calculated
using the following formulas:
Round cases:
V
RMS
=

11(.5 D
2
+
DL)
2 f C DF(%)
Oval cases:
V
RMS
= 21(TH +TL + HL)
2 f C DF(%)
D, T, H, and L are dimensions
taken from the ratings dimensions
chart.
Application Guide
Film Capacitors CDE Cornell Dubilier 1605 E. Rodney French Blvd. New Bedford, MA 02744 Phone: (508)996-8561 Fax: (508)996-3830 www.cde.com
DF is dissipation factor in percent
at operating frequency taken fr