MKP - TECHNOLOGY
Capacitors are used in many diverse applications, and
many different capacitor technologies are available. In low
voltage applications, MKP-type capacitors which are made
in accordance with metallized polypropylene technology
have proved to be most appropriate and also the most cost
effective. Dependent on the nominal voltage of the
capacitor, the thickness of the polypropylene film will differ.
MKP-TYPE CAPACITOR (metallized polypropylene film)
SELF-HEALING
At the end of service life, or due to inadmissible electrical
or thermal overload, an insulation breakdown may occur.
A breakdown causes a small arc which evaporates the
metal layer around the point of breakdown and
re–establishes the insulation at the place of perforation.
After electric breakdown, the capacitor can still be used.
The decrease of capacitance caused by a self-healing
process is less than 100pF. The self-healing process lasts
for a few microseconds only and the energy necessary for
healing can be measured only by means of sensitive
instruments.
For a self-healing dielectric, impregnation is basically not
required. However, our MKP-type capacitors are
impregnated to eliminate environmental influences and to
guarantee reliable, long-term operation. Vacuum
impregnation eliminates air and moisture, improves
“self–healing” and reduces thermal resistance.
IMPREGNATING AGENT (ESTAPROP)
ESTAprop®MKP-type capacitors are impregnated with a
specially treated oil. The highly fire-resisting insulation oil
on vegetable base (flash point 285°C, ignition point 315°C)
is fully biodegradable and nontoxic. There are no legal
regulations regarding its destruction so it can be safely
disposed of with ordinary refuse.
IMPREGNATION (ESTAPROP®)
After an extended drying period, the impregnation (filling
the capacitor casing with oil) is carried out under high
vacuum for removal of moisture. Following this process,
the capacitor will be hermetically sealed. This process
ensures excellent heat dissipation and constant
capacitance over full service life.
FILLING AGENT (ESTADRY®)
ESTAdry®MKP-type capacitors are "dry". That is, after the
extended drying period and before the hermetic sealing of
the casing, a non-liquid filling agent is used instead of
natural oil. In case of tubular cans, it is an environmentally
friendly inert gas-filling to avoid corrosion of the winding
elements and inner electric contacts. For larger dry
capacitors, e.g. the DW-Type Filter Capacitors, the filling
agent is a resin.
A little "g" shows the difference in the type designation
between the oil-impregnated (PhMKP) and the dry version
(PhMKPg).
We recommend the use of our oil-impregnated standard
tubular can type whenever possible, especially for filter
applications, as its thermal resistance is very low and it
therefore provides excellent heat dissipation, which
helps to overcome very high loads.
Both versions comply with the highest temperature class
D, specified by the standards. The oil-impregnated version
has more safety margin by design.
PROVIDING THE WINDING ELEMENT WITH ELECTRIC CONTACTS
For ESTAprop®and ESTAdry®MKP-type capacitors,
metallized electrodes are used. A winding element
consists of two displaced polypropylene films, wound
together. The front surface of the winding elements is
joined by means of a metal spray process. This process is
called Schooping. Due to the displacement of the two
polypropylene films, only one film will be electrically
connected on one side of the element. The terminal leads
can be soldered onto this sprayed metal surface.
Design of a MKP-type
capacitor
1 Electrodes (metallized)
2 Polypropylene film
3 Electric contact
(schooping)
4 Non-metallized edge
341 243
General Information
Vishay ESTA
Document Number: 13001
Revision 05-Sep-01 www.vishay.com
3
ESTAprop®/ESTAdry®Power Factor Correction
Capacitors Low Voltage
GENERAL TECHNICAL INFORMATION
Self-healing breakdown
1 Electrodes (metallized)
2 Polypropylene film
3 Point of breakdown
4 Non-conductive
insulating area
Winding element with
schooping and
soldered
connecting stripes
4312
1
3
4
General Information
Vishay ESTA
Document Number: 13001
Revision 05-Sep-01
www.vishay.com
4
OVERPRESSURE TEAR-OFF FUSE
If at the end of service life, due to inadmissible electrical
or thermal overload, an overpressure builds up and causes
an expansion of the cover. Expansion over a certain limit
causes the tear-off of the internal fuses. The active
capacitor elements are thus cut off from the source of
supply. The pressure within the casing separates the
breaking point so rapidly that no harmful arc can occur.
OPERATING CONDITION
TORN-OFF CONDITION
CHARACTERISTICS OF DIELECTRIC
MKP-POLYPROPYLENE, METALLIZED
CE-MARKING
ESTAprop®low voltage capacitors conform with the
ESTAdry®regulations of the following
European directives:
89/336/EWG Electromagnetic compatibility
92/31 /EWG Electromagnetic compatibility
93/68 /EWG Directive to change the directives
. . . 89/336/EWG
All ESTAprop®and ESTAdry®low voltage Power Factor
Correction Capacitors are supplied with CE - marking.
UL AND ULC-MARKING
ESTAprop®and ESTAdry®cylindrical type capacitors have
been tested and approved by independent laboratories
such as Underwriters Laboratories Inc.(UL). ESTAprop®
and ESTAdry®low voltage capacitors conform with UL-
standard 810 and Canadian standard C 22.2. UL and ULc
marks are included in standard component marking.
ESTAprop®/ESTAdry®Power Factor Correction
Capacitors Low Voltage
20 0 20 40 60 80 100
→→ ϑϑ = temp. [°C]
94
96
98
100
102
104 Capacitance = F [ϑϑ]
→→ C [%]
03 6 912
→→ Operating time in months
Losses = f [T]
0
0.5
1.0
1.5
2.0
→→ W/k var
0
0.5
1.0
1.5
2.0
→→ W/k var
0 20 40 60 80 100
→→ ϑϑ = temp. [°C]
Losses = f [ϑϑ]
