DEKI CAPACITOR SOLUTIONS
By
Vishnu –Engineer R&D
DEKI ELECTRONICS LTD
CAPACITOR…
A capacitor is a passive electronic component. It forms the
basic building block of an electronic circuit. Without
capacitor electronic circuits cannot be designed
 It is a device for storing electric charge.
 consisting of a pair of conductors separated by a
dielectric.
 for blocking direct current while allowing alternating
current to pass
 C = Q/V Farads
2
DEKI ELECTRONICS LTD
CAPACITOR…
ELECTRODE
DIELECTRIC
SYMBOL
CONSTRUCTION
3
DEKI ELECTRONICS LTD
Theory of Operation





When the supply is given to the
conducting plates.
The dielectric between the
conducting plates will polarize
and arrange themselves in a
regular fashion.
An electron flow occurs from
negatively charged plate to the
positively charged plate due to
polarization
Thus current flow from positively
charged plate to the negative
plate
The energy stored in the
capacitor is given by E=CV2/2
4
DEKI ELECTRONICS LTD
Parameters
A capacitor has four important parameters.



Rated Capacitance
Rated Voltage
Insulation Resistance

It is the measure of resistivity in dc. Under a stationary dc
voltage, a leakage current flows through the dielectric and over the
capacitance surfaces.


Rins =V (applied voltage)/I (Leakage current)
Loss Factor or dissipation Factor(Tanδ)
5
DEKI ELECTRONICS LTD
Dissipation Factor…

With a perfect dielectric capacitor, current will lead the applied voltage
by 90º. When dealing with less than perfect dielectric materials, current
in a capacitor will lead the applied voltage by less than 90°. This can be
visualized in the current-voltage phase relation of a dielectric visualized in
The loss angle is usually expressed as the tangent of delta, or just
tan delta(dissipation factor)
6
DEKI ELECTRONICS LTD
ESR & Power dissipation…
The ESR is the resistive part of the equivalent series circuit and is temperature
and frequency dependent. The ESR can be calculated from the dissipation factor
(tan δ) as follows:
ESR = tan δ / ϖC
The power dissipated by a capacitor is a function of the voltage across or the
current (I) through the equivalent series resistance ESR.
P = w × C × tan δ × U2
P = 2 × π × f × C × tan δ × U2
where f = frequency, tan δ = maximum value specified,
U =rated voltage
7
Types of capacitors
Depending upon the dielectric used,
there are several types of capacitors

Ceramic Capacitors

Paper capacitors

Glass capacitors

Electrolytic capacitors

Film capacitors




Polyester film dielectric
Polypropylene film dielectric
Polyethylene Naphthalate
dielectric
Polyphenylene sulphide
dielectric
DEKI ELECTRONICS LTD
DEKI Film CAPACITORS…
INDUCTIVE (MYLAR)
1 ) PP (POLYPROPYLENE)
2) PET (POLYESTER)
3) PEP (POLYPROPYLENE + POLYESTER)
4) PES
5) PSH
NON-INDUCTIVE
1 )MPP
2) MPET
3) PP-NI,PET-NI
4) PP-MPP
9
DEKI ELECTRONICS LTD
INDUCTIVE (MYLAR)
 High Dv/dt
 High IR
SIDE VIEW
PLAIN .FILM
FRONT VIEW
Al.FOIL
L.O.FILM
 Good Current carrying
capability.
 Better capacitance stability
D
104
K1J
10
DEKI ELECTRONICS LTD
NON-INDUCTIVE
METALLISED FILM 1
METALLISED FILM 1
METALLISED FILM 2
METALLISED FILM 2
For voltage 250 VAC
For voltage 500 VAC
METALLISED FILM 1
METALLISED FILM 2
 Smaller size.
 High Reliability
 Self Healing
For voltage 750 VAC
11
DEKI ELECTRONICS LTD
Self Healing…



For capacitors made with
metalized film, self-healing or
"clearing" removes a fault or
short circuit in the dielectric film
by vaporizing the metallization
near the defect
The vaporized metal oxidizes
over time, aiding in the isolation
of a fault area.
The self-healing feature of the
metallized capacitor offers a
distinct advantage over the nonmetallized unit.
12
DEKI ELECTRONICS LTD
Selection of films
If the maximum operating temperature




For
•
•
•

<=105oC <=120oC <=150oC >150oC
-
PP film
PET film
PEN film
PPS film (upto to 170oC)
PP film,
Tanδ<0.0008 at 1 kHz,
Tanδ<0.001 at 10 kHz,
Tanδ<0.003 at 100 kHz.
For
•
•
•
PET film,
Tanδ<0.008 at 1 kHz,
Tanδ<0.015 at 10 kHz,
Tanδ<0.030 at 100 kHz.
In cost, PPS>PEN>PP>PET film
13
DEKI ELECTRONICS LTD
Properties of Films
For PET film:
Dielectric constant Vs Temperature
C = εoεrA/D
For PP film:
14
DEKI ELECTRONICS LTD
Properties of Films
Tanδ Vs Temperature
ESR = tan δ / 2 fC
For PET film:
For PP film:
15
DEKI ELECTRONICS LTD
Properties of Films
Insulation resistance Vs Temperature
For PET film:
For PP film:
16
DEKI ELECTRONICS LTD
Comparison of films
17
DEKI ELECTRONICS LTD
Selection by application

DC Application
Vr > DC voltage of the signal
IR should be very high

AC Application
tanδ is very important
self-heating

Pulse Application
high current/voltage pulses at short durations
self-heating
18
WHY POLYPROPYLENE CAPACITOR FOR SWITCHING



Polypropylene capacitor is ideal choice for high frequency applications
because of its low loss factor. For striking, the capacitor should have
high dv/dt rating and low loss factor. Low loss factor is preferred
because
P = 2. . f.C.tan δ .VRMS2 --------(1)
∆T = P . RTH
C
--------(2)

P = power dissipation in capacitor. ∆T = Temperature Rise

RTH = Thermal resistance of the capacitor

From above eq. we can tell power dissipation is directly proportional to
the frequency, loss factor and VRMS .Heat generated in the capacitor is
proportional to the power dissipation. But temperature rise is not
allowed more than 10 C at its category temperature. For polypropylene
capacitors loss factor is low at high frequency .so the temperature rise
considerable less than other capacitor.
19
DEKI ELECTRONICS LTD
CFL…
20
DEKI ELECTRONICS LTD
CFL…( RFI Suppression and Startup)
RFI SUPPRESSION-(C1)
Cap Value : 68nf to 220nf
X2-Series –275 VAC
MPET –( 400 –630 Vdc)
START UP-(C2)
Cap Value :10nf to 100nf(63 –100Vdc)
PET Film foil inductive type
MPET For C > 0.082 Mfd
21
DEKI ELECTRONICS LTD
CFL…( Snubber & Blocking)
BLOCKING-(C4)
Recommended Capacitor is
PET ( Film/Foil) .
MPET ( Box &Dip)
Cap Value
: 0.022 –0.068μf
Rated Voltage : 250 –400Vdc
SNUBBER-(C3)
0.68nf to 0.0033μf(630-1000Vdc)
PP Film foil inductive
PEP film foil inductive
22
DEKI ELECTRONICS LTD
CFL…( Striking)
STRIKING-( C5)
cap 0.0022μF to 0.0068 μf.
PP inductive type
PET inductive type
PEP film foil inductive
DPSH
MPP-MPP
23
DEKI ELECTRONICS LTD
H.F Ballast…
P.F.C
For smoothening the wave
form after PFC correction
Deki has MPET as well as
MPP series .Range starts
from 10 nf to 10 Mfd .
Voltage range is from 420
VDC to 630 VDC.
RFI Filter
Capacitance value(RFI Filter) :
 0.0047 Mfd to 2.2 Mfd
(for C1-X2 Class (275VAC/305Vac)
0.001Mfd to 0.1 Mfd
(for C2,C3- 250 ~275VAC)
24
DEKI ELECTRONICS LTD
H.F Ballast… (Striking)
Deki Range …
AC & Pulse capacitor series
a) MPP/MPP AC-series
b) PP/MPP series
c) MMPP series
25
DEKI ELECTRONICS LTD
Selection of capacitor for striking
V
DURING STARING
NORMAL OPERATION
VP
VP-P
Following condition should be satisfied when selecting capacitor for
striking application.
 VP Should be less than D.C Rated voltage.
 VP-P should be less than 2x1.414x VRMS.
 dv/dt rating should be fulfilled
 Peak current should be less than C(dv/dt)
 Temperature rise should be less than 10˚C at its category
temperature.
26
DEKI ELECTRONICS LTD
Capacitors for Energy meters



A capacitive power supply is the best solution for a low-cost
energy meter. It works on the principle of reducing the line
voltage (Voltage dropper) by having a series capacitor between
phase and neutral. Current flowing through this capacitor is
inversely proportional to the impedance of the capacitor as
given by the formula:
Impedance (Z) = 1/(2πfC)
f is the line frequency and
C is the capacitance of the series impedance capacitor.
DEKI ELECTRONICS LTD
Capacitance
Function
Type
Voltage Range
Capacitance range
C1
Noise filter
MPP-X2
275Vac/305Vac
0.01 to 1μF
C2
Ripple filter
Electrolytic
-
-
C3 (Series
impeda
nce
capacit
or)
Voltage Dropper
MPP-AC, MPPX2, MPETAC-High
capacitance
stability
275Vac/305Vac,
325Vac,
440Vac
0.1 to 1μF
29