Film Capacitors – Power Electronic Capacitors

General purpose applications

Series/Type: FilterCap MKD AC – Single phase

Ordering code: B3237*F
Date: July 2024
Version: 02

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Identification/Classification 1 Film Capacitors – Power Electronic Capacitors
(header 1 + top left bar):
Identification/Classification 2 General purpose applications
(header 2 + bottom left header bar):
Ordering code: (top right header bar) B3237*F
Series/Type: (bottom right header bar) FilterCap MKD AC – Single phase
Preliminary data (optional):
Department: CAP PW PD
Date: July 2024
Version: 02

 TDK Electronics AG 2024. Reproduction, publication and dissemination of this publication, enclosures hereto and the
information contained therein without TDK Electronics' prior express consent is prohibited.
 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

Rated capacitance: 10 … 350 µF

Rated Voltage: 750 … 1415 V AC
RMS Voltage: 530 … 1000 V
Construction
 Metallized polypropylene film
 Aluminum can and top
 Filling material: Soft polyurethane resin (Non PCB)
 Diameter: 50/63.5/75/85/96/116/136 mm

Features
 Self-healing properties
 Low dissipation factor B32370F B32371F
 Overpressure disconnector
 Naturally air cooled (or forced air cooling)
 Protection Degree (indoor mounting)
o IP00: B32370, B32371 and B32373 series
o IP20: B32374 series
 RoHS compatible
 UL Certified

Application B32373F B32374F

 Input and output filters in inverter systems
 Filtering of harmonic distortion in power inverters

Terminals
 B32370F series: Fast-on terminals
 B32371F series: (M6) screw terminals type A and B
 B32373F series: (M10) screw terminals type A and B
 B32374F series: (M5) clamp terminals

Mounting
 Threaded stud on the bottom (M12)

Packing
 50 mm diameter: 50 capacitors per box
 63.5 mm diameter: 12 capacitors per box
 75 mm diameter: 6 or 9 capacitors per box
 85 mm diameter: 4 or 9 capacitors per box
 96/116/136 mm diameter: 4 capacitors per box

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

Specifications and characteristics

Rated capacitance CR: 10 … 350 μF Tolerance: ±5%
Technical data
Type/series Voltage vs Capacitance
B32370F VRMS
Fast-on terminal
Coming soon
600

530

0 20 40 60 80 µF

B32371F VRMS
Screw terminal M6
Coming soon 850

600

530

0 10 20 30 40 50 60 µF

B32373F VRMS
Screw terminal M10
Coming soon 1000
850
780
720
660
600
530
0 100 200 300 400 µF

B32374F VRMS
Clamp terminal M5
Coming soon
600

530

0 50 100 150 200 250 µF

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

Technical data and specifications

Reference standards IEC 61071-2017, UL 810 5th, GB/T 17702-2021, RoHS
compliance
Rated frequency fR 50/60 Hz
Voltage VRMS Rated AC voltage VN
530 750
600 850
660 935
720 1020
780 1100
850 1200
1000 1415
Test data
Voltage between terminals VTT 2.15 • VRMS, 2 s
Voltage between terminals and Case VTC 4000 V AC, 10 s
Reliability data
Lifetime expectancy (reference value)1 100 000 hours at 70 °C hotspot, rated voltage

Failure in time 100 FIT at 85 °C hotspot, rated voltage

Climatic category 40/70/21 IEC60068-1
Storage temperature Tstg −40 ...+70 °C
Minimum operation ambient temperature Tmin −40 °C
Maximum operation ambient temperature Tmax +70 °C
Damp Heat Test Ttest 21 days @ 40 °C, 93% RH
Maximum hot spot temperature in capacitor THS +85 °C
Max. permissible altitude 2000 m above sea level
Mechanical characteristics
Max. torque (for bottom stud) M12: 12 Nm
Max. torque (for terminals) B32371 (M6): 4 Nm
B32373 (M10): 10 Nm
B32374 Clamp terminal (M5): 2 Nm
Max insertion and withdraw force (for fast-on terminal) 50 N
Installation position2 Vertical with terminals upright

1
Lifetime expectancy detail refer to Figure 9
2
Capacitors are designed to be mounted with terminals upright. All tests during the approval of the series have been performed in vertical
position. Capacitors can be also installed in horizontal position, however, since it might have an impact in performance it is highly
recommended by us and it is customer duty to do the assessment on the electrical and mechanical performance with the customer mechanical
design, under specific customer working condition.
CAP PW PD July 2024

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

Approvals

B32370, B32371 type A, B32373 type A and UL 810, CSA C22.2, No 190, Max. 600 VRMS, 50/60Hz,
B32374: File no.: E487229, CCN:CYWT2/8 “Protected”, 10K AFC, max. +70 °C

B32371 type B and B32373 type B:. File no.: UL 810, CSA C22.2, No 190, Max.1000 VRMS 50/60Hz,
E487229, CCN:CYWT2/8 “Protected”, 10K AFC, max. +70 °C

Structure of ordering code

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

Electrical characteristics

B32371F series - M6 screw terminals (Type B)

VN/VRMS 3 CR Ordering code IRMS,max IRMS,max Î Is Rth 6 Rs 7 tan δ 8 ESL 9 D H Weight Packing
at 60 °C 4 at 70 °C 5
V μF A A A A K/W mΩ ×10-3 nH mm mm kg Unit
1200/850 33 B32371F8336J050 41 29 2030 6000 3.9 2.0 2.0 130 85 145 1.00 4

B32373F series - M10 screw terminals (Type A)

VN/VRMS 3 CR Ordering code IRMS,max IRMS,max Î Is Rth 6 Rs 7 tan δ 8 ESL 9 D H Weight Packing
at 60 °C 4 at 70 °C 5
V μF A A A A K/W mΩ ×10-3 nH mm mm kg Unit
50 B32373F5506J030 45 33 2330 6900 4.9 1.3 2.0 100 75 120 0.65 9
60 B32373F5606J030 44 35 2700 8100 4.2 1.3 2.0 100 85 120 0.80 4
750/530
150 B32373F5157J030 64 46 5920 17700 2.6 0.8 3.0 100 116 145 1.70 4
10
300 B32373F5307J030 67 -- 5130 15400 2.1 1.2 6.0 100 116 245 2.85 4

B32373F series – M10 screw terminals (Type B)

VN/VRMS 3 CR Ordering code IRMS,max IRMS,max Î Is Rth 6 Rs 7 tan δ 8 ESL 9 D H Weight Packing
at 60 °C 4 at 70 °C 5
V μF A A A A K/W mΩ ×10-3 nH mm mm kg Unit
935/660 50 B32373F6506J060 35 25 1050 3100 3.8 2.8 2.5 130 85 142 1.00 4
20 B32373F7206J020 33 24 810 2400 5.6 2.7 1.5 130 75 102 0.60 6
33 B32373F7336J020 62 46 1330 3900 3.9 0.9 1.5 100 96 102 0.85 4
50 B32373F7506J020 47 33 1140 3400 3.8 1.9 2.5 130 85 142 1.00 4
1020/720 60 B32373F7606J020 46 33 1360 4100 3.3 1.9 2.0 100 96 142 1.15 4
80 B32373F7806J020 61 43 2530 7500 2.8 0.6 2.0 100 96 195 1.60 4
100 B32373F7107J020 44 29 2250 6750 2.9 1.9 3.0 130 85 245 1.55 4
150 B32373F7157J020 62 42 4100 12300 2.1 1.0 4.5 100 116 215 2.45 4
1100/780 68 B32373F7686J080 53 37 2320 6900 2.8 1.6 2.5 100 96 195 1.60 4

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

B32373F series – M10 screw terminals (Type B)

VN/VRMS 3 CR Ordering code IRMS,max IRMS,max Î Is Rth 6 Rs 7 tan δ 8 ESL 9 D H Weight Packing
at 60 °C 4 at 70 °C 5
V μF A A A A K/W mΩ ×10-3 nH mm mm kg Unit
33 B32373F8336J050 38 27 2030 6000 3.9 2.7 1.5 130 85 145 1.00 4
40 B32373F8406J050 39 27 1870 5600 3.7 2.4 2.0 100 85 165 1.15 4
1200/850
68 B32373F8686J050 41 27 1810 5400 2.9 2.2 2.5 130 85 245 1.55 4
100 B32373F8107J050 56 35 3680 11000 2.2 1.5 3.0 100 116 195 2.15 4
20 B32373F1206J000 37 27 660 1900 3.8 3.0 1.5 130 85 142 1.00 4
1415/1000
45 B32373F1456J000 43 29 1480 4400 2.9 2.2 2.0 130 85 245 1.55 4

Display of ordering codes for TDK Electronics products

The ordering code for one and the same product can be represented differently in data sheets, data books,
other publications, on the company website, or in order-related documents such as shipping notes, order
confirmations and product labels. The varying representations of the ordering codes are due to
different processes employed and do not affect the specifications of the respective products.
Detailed information can be found on the Internet under www.tdk-electronics.tdk.com/orderingcodes

3
VN Rated AC Voltage / VRMS, complete explanation in the section Terms.
4
Max permissible IRMS,max current at 60 ºC for THS ≤85 ºC, ∆Tmax ≤ 25 K, considering a harmonic spectrum up to 10 kHz.
IRMS,max derating vs temperature refer to the permissible current versus ambient temperature curve
5
Max permissible IRMS,max current at 70 ºC for THS ≤85 ºC, ∆Tmax ≤ 15 K, considering a harmonic spectrum up to 10 kHz.
IRMS,max derating vs temperature refer to the permissible current versus ambient temperature curve
6
Thermal resistance ambient to HS, considering natural convection (10 W/(m2.K)), terminals without temperature fixation and bottom screw
connected to a piece with big thermal inertia
7
Series resistance -Rs- at 1 kHz is a typical value (only valid for low frequency range)
8
Max tan δ at 1 kHz
9
ESL at 1 MHz (typical value)
10
Climatic category 40/60/21

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

Electrical characteristics: Clearance and creepage distances

Series Diameter D Max. height Hmax Terminal to terminal Terminal to case
Min. Min. Min. Min.
clearance creepage clearance creepage
mm mm mm mm mm mm
B32370 50/63.5 137 10 36 16 17
B32371
63.5 142 23 34 13 14
Type A
B32371
75/85/96/116/136 265 20 28 19 20
Type B
B32373
75/85/96/116/136 265 15 26 15 18
Type A
B32373
75/85/96/116/136 265 15 37 20.5 25.6
Type B
B32374 75/85/96/116/136 265 35 32 17 18

Permissible current versus ambient temperature curve

B32373F5307J030 B32373F7157J020
Current derating @ THS = 85 °C Current derating @ THS = 85 °C

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

B32373F7686J080 B32373F8406J050
Current derating @ THS = 85 °C Current derating @ THS = 85 °C

Permissible current versus ambient temperature curve for other types upon request.

Label Information
Date code explanation
WW Z YYYY: production week (e.g.: CW 32)
WW Z YYYY: produced in Zhuhai (China)
WW Z YYYY: production year (e.g.: 2023)

Bar code explanation

Bar code consists of batch number and serial
number.
Batch number: 9 digits (e.g.: 123456789)
Serial number: 3 digits (e.g.: 001)

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

Dimensional drawings
B32370F – fast on terminal

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

B32371F – M6 screw terminal type A

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

B32371F– M6 screw terminal type B

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

B32373F – M10 screw terminal type A

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

B32373F – M10 screw terminal type B

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 Film Capacitors – Power Electronic Capacitors B3237*F
General purpose applications FilterCap MKD AC – Single phase

B32374F – M5 Clamp terminal

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 Film Capacitors – Power Electronic Capacitors B3237*F
General information FilterCap MKD AC – Single phase

Terms

Design
The winding element of the MKD capacitor consists of metallized polypropylene film. This winding
construction achieves low losses and a high pulse-current withstand capability. Soft PU resin is used
for impregnation of the capacitor.

Contacting
The end faces of the windings are contacted by metal spraying to ensure a reliable and low-inductance
connection between the leads and layers. The leads are welded or soldered to these end faces, brought
out through insulating elements (plastic) and soldered to the terminals.

Filler material
All hollows between the windings and between the windings and the case are filled with a fluid.
Besides increasing dielectric strength, this improves heat dissipation from inside a capacitor. The filler
material that we use is free of PCB and halogens.
Self-healing
All MKD capacitors are self-healing, i.e. voltage breakdowns heal in a matter of microseconds and
hence do not produce a short circuit.
Breakdowns can occur under heavy electrical load as a result of weaknesses or pores in the dielectric.
The integrity of self-healing capacitors is not affected by such breakdowns.

1. Dielectric (Polypropylene) 7. Boundary layer between gas-phase

2. Metallization dielectric and plasma zones
3. Material-displacing shock wave 8. Puncture channel
4. Air gap with metal vapor 9. Gas-phase dielectric
5,6. Plasma zone 10. Zone of displaced metallization and
dielectric
Figure 1: Description of self-healing technology

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 Film Capacitors – Power Electronic Capacitors B3237*F
General information FilterCap MKD AC – Single phase

When a breakdown occurs, the dielectric in a breakdown channel is broken down into its atomic
components by the electric arc that forms between the electrodes. At the high temperatures of as much
as 6000 K, a plasma is created that explodes out of the channel region and pushes the dielectric layers
apart. The actual self-healing process starts with the continuation of the electric arc in the propagating
plasma. Here the metal layers are removed from the metal edges by evaporation. Insulation areas are
formed. The rapid expansion of the plasma beyond the areas of insulation and its cooling in the areas
of less field strength allow the discharge to extinguish after a few microseconds.

The area of insulation that is created is highly resistive and voltage-proof for all operating requirements
of the capacitor. The self-healing breakdown is limited in current and so it does not represent a short
circuit. The self-healing process is so brief and low in energy that the capacitor also remains fully
functional during the breakdown.

Characteristics

Equivalent circuit diagram

Any real capacitor can be modelled by the following schematic:

Figure 2: Equivalent circuit diagram

Symbol Description Unit

Ls series inductance H
Rs series resistance, due to contacts (leads, sprayed metal and film Ω
metallization)
Rp parallel resistance, due to insulation resistance Ω
C capacitance F

C and LS are magnitudes that vary in the frequency domain (AC).

RP is a magnitude defined in DC (insulation resistance).

Rated capacitance CR
It is referred to a test temperature of +20 ℃ and a measuring frequency range of 50 Hz to 1 kHz.

Capacitance tolerance range

It is the range within which the actual capacitance may differ from rated capacitance. The actual
capacitance is to be measured at a temperature of +20 ℃. This range results from variances in materials
and manufacturing processes. The standard manufacturing tolerance for PP film capacitors is ±10% or
‘K’ tolerance or ±5%, ‘J’ tolerance.
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 Film Capacitors – Power Electronic Capacitors B3237*F
General information FilterCap MKD AC – Single phase

Temperature dependence of capacitance

The capacitance variation in the permissible temperature range is not linear, but it is reversible, the
characteristic change in capacitance ΔC/C as a function of test temperature is shown as follows:

Relative Capacitance Change

ΔC/C versus Temperature T
2%
0%
-2%
ΔC/C

-4%
-6%
-8%
-60 -40 -20 0 20 40 60 80 100
T(℃)
Figure 3: Temperature dependence of capacitance

Capacitance drift
Capacitance is subject to irreversible in addition to reversible changes, i.e. capacitance drift, the sum
of all time-dependent, irreversible changes of capacitance during operating life. This variation is stated
in percent of the value at delivery. The typical figure is +1/−3%.

Rated AC voltage VN
The maximum operating peak recurrent voltage of either polarity of a reversing type waveform for which
the capacitor has been designed.
Unlike what is common in other standard (e.g. B32304* 3–phase capacitor series for PFC application)
the rated voltage VN is not the RMS value, but the maximum or peak value of the capacitor voltage.
The voltage at which the capacitor may be operated is dependent on other factors (especially current
and frequency) besides rated voltage.

Voltage VRMS
It is the Root Mean Square (RMS) voltage of maximum permissible value of sinusoidal AC voltage in
continuous operation.

Figure 4: Voltage VRMS

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General information FilterCap MKD AC – Single phase

Non-recurrent surge voltage VS

A peak voltage induced by a switching or any other disturbance of the system which is allowed for a
limited number of times and for durations shorter than the basic period.

Figure 5: Non-recurrent surge voltage VS

Maximum duration: 50 ms/pulse

Maximum number of occurrences: 1000 (during load)

Max. Recurrent peak voltage û

This is the permissible, max. recurrent peak voltage that may appear for max.1% of the period.

Figure 6: Max. Recurrent peak voltage û

Symmetric alternating voltage û𝒂𝒄

The peak values of a symmetrical alternating voltage applied to the capacitor is a decisive factor for the
dielectric losses.
For AC capacitors: û V
Insulation voltage Vi
It is the RMS rated value of the insulation voltage of capacitive elements and terminals to case or earth.
If not specified, the RMS value of the insulating voltage is equivalent to the rated voltage divided by √2.

Maximum current IRMS,max

It is the maximum RMS current for continuous operation which, at rated temperature and for given
harmonic distortion, will lead to a maximum hot-spot temperature (THS) of 85 °C.
Note that RMS current with different harmonic distortions could generate different self-heating
temperatures. A higher current than IRMS,max value could be possible if the hot-spot temperature (THS)
is lower than 85 °C. On the contrary, same RMS current with more harmonic distortions at higher
frequency could have higher self-heating temperature that makes THS higher than 85 °C (dangerous for
capacitor). For that reason, we strongly suggest end customers to qualify capacitor using
samples with thermocouples (upon request) in order to verify the real operating temperature
inside of capacitor under real application or to check with TDK company for detail discussions.
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 Film Capacitors – Power Electronic Capacitors B3237*F
General information FilterCap MKD AC – Single phase

Maximum peak current I

It is the maximum current amplitude which occurs instantaneously during continuous operation. The
maximum peak current and the maximum rate of voltage rise (dV/dt)max on a capacitor are related as
follows:

dV
I C ∙
dt
Maximum surge current I
It is the peak non-repetitive current induced by switching or any other disturbance of the system
permitted for a limited number of times, at durations shorter than the basic period.
dV
I C ∙
dt
Maximum duration: 50 ms/pulse
Maximum number of occurrences: 1000 (during load)

Fault current (AFC)

It is a failure mode in which capacitor is intentionally internally faulted to represent dielectric breakdown
that would occur within the capacitor over time.
The fault current test is intended to address protection of the capacitor from available fault currents over
the life of the capacitor. The maximum fault current test levels represent a complete internal dielectric
breakdown in the capacitor with the maximum fault current available. The lower fault current test levels
represent the various stages of internal dielectric breakdown during the life of the capacitor where the
available fault current will be less.

Self-inductance L
The self-inductance is produced by the inductance of the terminals and the windings. Because of the
special kind of contacting in self-healing capacitors (large area metal spraying covering all windings),
the self-inductance is particularly low. It allows the resonance frequency to be determined:
1
f
2π L ∙C
The resonance frequency is high for all capacitors accordingly.

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 Film Capacitors – Power Electronic Capacitors B3237*F
General information FilterCap MKD AC – Single phase

Insulation Resistance (Rins)

The dielectric of a capacitor has a large area and a short length. Even if the material is a good isolator
there always flows a certain current between the charged electrodes (the current increases
exponentially with the temperature). This leakage can be described as a parallel resistance with a high
value, an Insulation Resistance.

Figure 7: Insulation Resistance (Rins)

Insulation resistance and self-discharge time constant

The insulation values for the individual components according to the capacitance are stated as an
insulation resistance Rins in MΩ or a self-discharge time constant τ in seconds.

τ R ∙C

Series resistance RS
Resistive losses occur in the electrodes in the contacting and in the inner wiring. These are comprised
in the series resistance RS of a capacitor.
The series resistance RS generates the ohmic losses (I2ⅹRS) in a capacitor. It is largely independent
of frequency.

Dissipation factor tan δ

The equivalent circuit diagram used for the losses in a capacitor can be shown as follows:

Figure 8: Simplified equivalent circuit diagram of a capacitor

Symbol Description Unit

C Capacitor F
Lself Self-inductance H
ESR Equivalent series resistance, representing the entire active power in Ω
capacitor

The self-inductance and capacitance of a capacitor produce its resonance frequency (natural
frequency).
tan δ f tan δ Rs ∙ ω ∙ C

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General information FilterCap MKD AC – Single phase

From the frequency dependence of the equivalent series resistance can be derived:

tan δ tan δ
ESR Rs
ω∙C ω∙C
Symbol Description Unit
tan δ Dissipation factor of capacitor -
tan δ0 Dissipation factor of dielectric -
RS Series resistance Ω

Dielectric dissipation factor tan δ0

The dissipation factor tan δ0 of the dielectric is assumed to be constant for all capacitors in their
frequency range of use. The figures stated in data sheets apply to rated operation.

Expected FIT rate λ

The FIT (Failure In Time) of a component is defined as the number of expected failures in 109 hours of
operation.

The FIT rate is calculated based on the number of components operating in the field and the estimated
hours of operation. Field failure information is taken into consideration for this calculation which is
updated every year.

Thermal design
In order to scale a capacitor correctly for a particular application, the permissible ambient temperature
versus maximum current must be determined as explained along this chapter.

Introducing power dissipation (P) and thermal resistance (Rth) concepts are required for this estimation.

Calculation of power dissipation P

At each frequency the power dissipation P is composed of the dielectric losses (PD) and the resistive
losses (PR).
Generally, a secondary sinusoidal AC voltage can be used for calculating with sufficient accuracy,
besides fundamental frequency.
𝑃 𝑓 𝑃 𝑓 𝑃 𝑓
Which can be also calculated as:
𝑃 𝑓 𝐼 𝑓 ∙ 𝐸𝑆𝑅 𝑓
Dielectric losses (PD) at each frequency fi can be calculated as follows:

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General information FilterCap MKD AC – Single phase

𝐼 𝑓
𝑃 𝑓 𝑉 𝑓 ∙ 2𝜋 ∙ 𝑓 ∙ 𝐶 ∙ 𝑡𝑎𝑛 𝛿 ∙ 𝑡𝑎𝑛 𝛿
2∙𝜋∙𝑓 ∙𝐶

Symbol Description Unit

V(fi) RMS voltage at frequency fi applied to capacitor V
I(fi) RMS current at frequency fi applied to capacitor A
fi Frequency Hz
C Capacitance F
tan δ0 Dissipation factor of dielectric -

Note: value of dielectric losses (PD) at frequencies much higher than fundamental frequency are
negligible.

Resistive losses (PR) at each frequency fi can be calculated as follows:

P 𝑓 I 𝑓 ∙𝑅

Symbol Description Unit

I(fi) RMS current at frequency fi applied to capacitor A
RS Series resistance Ω

The total power dissipation P will be:

𝑃 𝑃 𝑓 𝑃 𝑓

Which can be also simplified as follows:

𝑃 𝑃 𝑓 𝑃 𝑓 𝑉 ∙ 2𝜋 ∙ 𝑓 ∙ 𝐶 ∙ 𝑡𝑎𝑛 𝛿 𝐼 ∙𝑅

Or alternatively:

𝑃 𝐼 𝑓 ∙ 𝐸𝑆𝑅 𝑓

Symbol Description Unit

VRMS RMS voltage at fundamental frequency f0 applied to capacitor V
I Total RMS current applied to capacitor A
f0 Fundamental frequency Hz

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General information FilterCap MKD AC – Single phase

C Capacitance F
ESR(fi) Equivalent Series Resistance at frequency fi Ω
tan δ0 Dissipation factor of dielectric -

Thermal resistance Rth

The thermal resistance is defined as the ratio of a temperature difference and the power dissipation
produced in a capacitor. The decisive factor here is ΔT where the temperature difference between
an external reference point of the coolant (e.g. air) surrounding the capacitor and the hot spot (zone
with highest temperature occurring in the component). In a steady state:
∆𝑇
R
P
Symbol Description Unit
Rth Thermal resistance (ambient to hot-spot) K/W
ΔT Temperature difference between hot-spot and ambient K
P Power dissipation W

Thermal design: Estimation of hot-spot temperature in capacitor (THS)

As a basic rule of thermal design, hot-spot can never exceed a maximum temperature of 85 ºC, what
means:
𝑇 𝑇 ∆T 𝑇 P∙𝑅 85 ℃

Symbol Description Unit

Tamb Ambient temperature around capacitor ºC
ΔT Temperature difference between hot-spot temp. and ambient K
P Power dissipation W
Rth Thermal resistance (ambient to hot-spot) K/W

Else, maximum currents can be taken from the diagram of Permissible current versus ambient
temperature.

CAP PW PD July 2024

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Important notes at the end of this document.
 Film Capacitors – Power Electronic Capacitors B3237*F
General information FilterCap MKD AC – Single phase

Thermal design example

Capacitor electrical parameters

Reference B32373F7686J080
VRMS 780 V (50Hz)
IRMS,max 37 A (70ºC)
Capacitance 68 µF
Rs 1.6 mΩ
Rth 2.8 K/W
tan δ0 0.0002 -

Operating conditions
VRMS 780 V (50Hz)
Fundamental frequency (f0) 50 Hz
Ripple frequency (f1) 8,000 Hz
IRMS total 21 A
Tamb 40 ºC
1) Verification of initial requirements

a. IRMS total = 21 A ≤ 37 A
b. VRMS = 780 V ≤ 780 V

2) Estimation of THS

𝐼 50 𝐻𝑧 780 ∙ 2𝜋 ∙ 50 ∙ 68 ∙ 10 16.7𝐴
𝐼 8 𝑘𝐻𝑧 21 16.7 12.7𝐴

𝐼 50 𝐻𝑧
𝑃 50 𝐻𝑧 ∙ 𝑡𝑎𝑛𝛿0
2 ∙ 𝜋 ∙ 𝑓 ∙ 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑎𝑛𝑐𝑒
16.7
𝑃 50 𝐻𝑧 ∙ 0.0002 2.598 𝑊
2 ∙ 𝜋 ∙ 50 ∙ 68 ∙ 10

𝐼 8 𝑘𝐻𝑧
𝑃 8 𝑘𝐻𝑧 ∙ 𝑡𝑎𝑛𝛿0
2 ∙ 𝜋 ∙ 𝑓 ∙ 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑎𝑛𝑐𝑒

12.7
𝑃 8𝑘 𝐻𝑧 ∙ 0.0002 0.009𝑊
2 ∙ 𝜋 ∙ 8,000 ∙ 68 ∙ 10

CAP PW PD July 2024

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Important notes at the end of this document.
 Film Capacitors – Power Electronic Capacitors B3237*F
General information FilterCap MKD AC – Single phase

P 50 Hz 16.7 ∙ 0.0016 0.446 W

P 8 kHz 12.7 ∙ 0.0016 0.258 W

𝑃 𝑃 50 𝐻𝑧 𝑃 8 𝑘𝐻𝑧 𝑃 50 𝐻𝑧 𝑃 8 𝑘𝐻𝑧

𝑃 2.598 0.009 0.446 0.258 3.311 𝑊

𝛥𝑇 𝑃∙R 3.311 ∙ 2.8 9.3 𝐾

𝑇 𝑇 ∆T 40 9.3 49.3 ℃ 85 ℃

Lifetime Expectancy Graphs

Figure 9: Expected lifetime in hours at different hotspot temperatures (THS) and voltages VRMS.

Lifetime estimations are typical values derived from lifetime tests based on TDK internal standards
or mutually agreed test methods and are intended for guidance purposes only. The useful life does
not constitute a warranty of any kind or a prolongation of the agreed warranty period.

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Important notes at the end of this document.
 Cautions and Warnings

General
 In case of dents of more than 1 mm depth or any other mechanical damage, capacitors must not be
used at all.
 Check tightness of the connections/terminals periodically.
 The energy stored in capacitors may be lethal. To prevent any chance of shock, discharge and short-
circuit the capacitor before handling.
 Failure to follow cautions may result, worst case, in premature failures, bursting and fire.
 Protect the capacitor properly against over current and short circuit.
 TDK Electronics is not responsible for any kind of possible damages to persons or objects due to
improper installation and application of capacitors for power electronics.
Safety
 Electrical or mechanical misapplication of capacitors may be hazardous. Personal injury or property
damage may result from bursting of the capacitor or from expulsion melted material due to
mechanical disruption of the capacitor.
 Ensure good, effective grounding for capacitor enclosures.
 Observe appropriate safety precautions during operation (self-recharging phenomena and the high
energy contained in capacitors).
 Handle capacitors carefully, because they may still be charged even after disconnection.
 The terminals of capacitors, connected bus bars and cables, as well as other devices, may also be
energized after disconnecting.
 Follow good engineering practices.
 When power capacitors are used, suitable measures must always be taken to eliminate possible
danger to humans, animals and property both during operation and when a failure occurs. This
applies to capacitors both with and without protective devices. Regular inspection and maintenance
by trained personnel is therefore essential.
 The maximum permissible fault current (AFC) of 10 kA in accordance with the UL 810 standard must
be assured by the application.
Handling
Do not handle the capacitor before it is discharged! When handling the capacitor, do not take the
capacitor from the terminal. This can cause accidents in case the capacitor is charged and additionally
the terminal could break.
Thermal load
After installation of the capacitor, it is necessary to verify that the maximum hot-spot temperature is not
exceeded at extreme service conditions.
Installation
Capacitors must be installed in a cool and well-ventilated place, away from objects that radiate heat,
or from direct sunlight. Within high-power inverter systems the capacitors usually produce the
smallest portion of the total losses, and the permissible operating temperatures are low compared to
power semiconductors, reactors and resistors. So, the distance between capacitor and heating
sources must be far enough to prevent the capacitor from overheating. In case of space constraint to
make the best possible use of capacitors, technically and economically, it is advisable to supply

CAP PW PD July 2024

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Important notes at the end of this document.
 Cautions and Warnings

forced cooling air.

Mechanical protection
The capacitor has to be installed in a way that mechanical damages and dents in the aluminum can be
avoided.
Connecting
Ensure firm fixing of terminals, fixing torque to be applied as per individual specification.
In any case, the maximum specified terminal current may not be exceeded. Please refer to the
technical data of the specific series.
Grounding
The threaded bottom stud of the capacitor must be used for grounding. In case grounding is done via
metal chassis where the capacitor is mounted on, the layer of varnish beneath the washer and nut
should be removed. In case, capacitor with plastic case, this is not applicable. Ensure the tightening
torque does not exceed the specified limit.
Maintenance recommendation
Disregarding the following measures may result in severe operation failures, bursting and fire:
 Check tightness of the connections/terminals periodically.
 Clean the terminals/bushings periodically to avoid short circuits due dust or other contamination.
 Ensure the current does not exceed the limit.
 In case of a current above the nominal current check your application for modification.
 Check the temperature of energized capacitors. In case of excessive temperature of individual
capacitors, it is recommended to replace this capacitor, as this could be an indication for loss factor
increase, which is a sign for reaching end of life.

Storage and operating conditions

Do not use or store capacitors in corrosive atmosphere, especially where chloride gas, sulfide gas,
acid, alkali, salt or the like are present. In dusty environments regular maintenance and cleaning
especially of the terminals is required to avoid conductive path between phases and/or phases and
ground.
 Capacitors must not be stored in high temperatures and/or high humidity, we recommend the
following storage conditions
 Temperature between -40 °C ~ 40 °C
 Humidity <= 80% RH as average per year
 Storage should not exceed 2 years (from the date code printed on the capacitor). After 1 year of
storage time, capacitors must be checked electrically.

Overpressure disconnector
To ensure full functionality of an overpressure disconnector, the following must be observed:
1. The elastic elements must not be hindered, i.e.
 Connecting lines must be flexible leads (cables).

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Important notes at the end of this document.
 Cautions and Warnings

 There must be sufficient space (min.20 mm) for expansion above the connections.
 Metal cover must not be retained by rigid parts, like: bus bars.
2. Stress parameters of the capacitor must be within the IEC 61071-2017 specification.

NOTE 1: As the actual conditions can be significantly different in service, the behavior at the end
of life may also be different. Stored energy expected short-circuit current, duration of failure current
(and so on) has to be considered in the application. Compliance with IEC 61071-5.16 does not
guarantee safe end of life of a capacitor.
NOTE 2: Successful completion of the IEC 61071-5.16 test is not sufficient to guarantee the total
safe failure of the components in service. For this reason, there is a residual risk of fire and/or
explosions that has to be carefully taken in consideration.
Lifetime expectancy
As a rule, TDK Electronics is unfamiliar with individual customer applications or less familiar with them
than the customers themselves. The results will not contain the various influences which might occur
in respect to TDK products, when TDK products will be incorporated into the customer application.
For these reasons, it is ultimately incumbent on the customer to check and decide whether a TDK
product with the properties described in the product specification is suitable for use in a particular
customer application.
We also point out that in individual cases a malfunction of electronic components or failure before the
end of their usual service life cannot be completely ruled out in the current state of the art, even if they
are operated as specified. In customer applications requiring a very high level of operational safety
and especially in customer applications in which the malfunction or failure of an electronic component
could endanger human life or health (e.g. in accident prevention or life-saving systems), it must
therefore be ensured by means of suitable design of the customer application or other action taken by
the customer (e.g. installation of protective circuitry or redundancy) that no injury or damage is
sustained by third parties in the event of malfunction or failure of an electronic component.

CAP PW PD July 2024

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Important notes at the end of this document.
 Important notes

The following applies to all products named in this publication:

1. Some parts of this publication contain statements about the suitability of our products for
certain areas of application. These statements are based on our knowledge of typical
requirements that are often placed on our products in the areas of application concerned. We
nevertheless expressly point out that such statements cannot be regarded as binding
statements about the suitability of our products for a particular customer application. As a
rule we are either unfamiliar with individual customer applications or less familiar with them than the
customers themselves. For these reasons, it is always ultimately incumbent on the customer to
check and decide whether a product with the properties described in the product specification is
suitable for use in a particular customer application.
2. We also point out that in individual cases, a malfunction of electronic components or failure
before the end of their usual service life cannot be completely ruled out in the current state
of the art, even if they are operated as specified. In customer applications requiring a very high
level of operational safety and especially in customer applications in which the malfunction or failure
of an electronic component could endanger human life or health (e.g. in accident prevention or life-
saving systems), it must therefore be ensured by means of suitable design of the customer
application or other action taken by the customer (e.g. installation of protective circuitry or
redundancy) that no injury or damage is sustained by third parties in the event of malfunction or
failure of an electronic component.
3. The warnings, cautions and product-specific notes must be observed.
4. In order to satisfy certain technical requirements, some of the products described in this
publication may contain substances subject to restrictions in certain jurisdictions (e.g.
because they are classed as hazardous). Useful information on this will be found in our Material
Data Sheets on the Internet (www.tdk-electronics.tdk.com/material). Should you have any more
detailed questions, please contact our sales offices.
5. We constantly strive to improve our products. Consequently, the products described in this
publication may change from time to time. The same is true of the corresponding product
specifications. Please check therefore to what extent product descriptions and specifications
contained in this publication are still applicable before or when you place an order.
We also reserve the right to discontinue production and delivery of products. Consequently,
we cannot guarantee that all products named in this publication will always be available.
The aforementioned does not apply in the case of individual agreements deviating from the
foregoing for customer-specific products.
6. Unless otherwise agreed in individual contracts, all orders are subject to our General Terms and
Conditions of Supply.
7. Our manufacturing sites serving the automotive business apply the IATF 16949 standard.
The IATF certifications confirm our compliance with requirements regarding the quality
management system in the automotive industry. Referring to customer requirements and customer
specific requirements (“CSR”) TDK always has and will continue to have the policy of respecting
individual agreements. Even if IATF 16949 may appear to support the acceptance of unilateral
requirements, we hereby like to emphasize that only requirements mutually agreed upon can
and will be implemented in our Quality Management System. For clarification purposes we like
to point out that obligations from IATF 16949 shall only become legally binding if individually agreed
upon.

Page 30 of 31
 Important notes

8. The trade names EPCOS, CarXield, CeraCharge, CeraDiode, CeraLink, CeraPad, CeraPlas,
CSMP, CTVS, DeltaCap, DigiSiMic, FilterCap, FormFit, InsuGate, LeaXield, MediPlas, MiniBlue,
MiniCell, MKD, MKK, ModCap, MotorCap, PCC, PhaseCap, PhaseCube, PhaseMod, PhiCap,
PiezoBrush, PlasmaBrush, PowerHap, PQSine, PQvar, SIFERRIT, SIFI, SIKOREL, SilverCap,
SIMDAD, SiMic, SIMID, SineFormer, SIOV, SurfIND, ThermoFuse, WindCap, XieldCap are
trademarks registered or pending in Europe and in other countries. Further information will be
found on the Internet at www.tdk-electronics.tdk.com/trademarks.

Release 2024-02

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