Epcos EMC filters General Product Line Information

EMC filters

General

Date: January 2006

General

EMC basics

1 EMC basics

1.1 Legal background

Electromagnetic compatibility (EMC) has become an essential property of electronic equipment. In view of the importance of this topic, the European legislator issued the EMC Directive as early as 1996 (89/336/EEC): it has since been incorporated at national level by the EU member states in the form of various EMC laws and regulations.

The EU’s new EMC Directive (2004/108/EC of December 15, 2004) contains several significant innovations compared to the version in force since 1996. It will become binding on all equipment put on the market after the elapse of the transitional period in July 2009. The most important changes include:

 Regulations for fixed installations  Abolition of the “competent body”  Conformity assessment may also be made without harmonized standards  New definitions of terms (”equipment”, “apparatus”, “ fixed installation”)  New requirements on mandatory information, traceability  Improved market surveillance

The definition of “apparatus“ has now become clearer, so that its scope of validity now covers only apparatus that the end user can use directly. Basic components such as capacitors, inductors and filters are definitively excluded.

The “essential requirements” must be observed by all apparatus offered on the market within the EU. This ensures that all apparatus operate without interferences in its electromagnetic environment without affecting other equipment to an impermissible extent.

1.2 Directives and CE marking

Manufacturers must declare that their apparatus conform to the protection objectives of the EMC Directive by attaching the CE conformity mark to all apparatus and packaging. This implies that they assume responsibility vis-à-vis the legislators for observing the relevant emission limits and interference immunity requirements.

The interference immunity requirements in particular are becoming increasingly important for the operators of apparatus, installations and systems, as their correct functioning can be ensured only if sufficient EMC measures are taken. However, the need for constant functionality also implies high availability of installations and systems and thus represents a significant performance figure for the cost-effective operation of the equipment.

It should be noted that the CE conformity mark not only asserts electromechanical compatibility but also confirms the observance of all the EU Directives applying to the product concerned. The most important general directives apart from the EMC Directive include the Low-Voltage Directive and the Machinery Directive.

Some of these directives also include EMC requirements. Examples are the R&TTE Directive (for radio and telecommunications terminal equipment) and the Medical Products Directive. The EMC Directive does not apply to those products which are covered by these directives.

The manufacturer is responsible for taking the necessary steps to ensure that all applicable directives are observed.

Please read Important notes and Cautions and warnings.

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General

EMC basics

1.3 EMC standards

Dedicated product standards or product family standards are available for many kinds of equipment (see Section 1.9). All equipment not covered by these EMC standards are assessed on the basis of the generic standards. Special rules apply to larger and more complex installations which are assembled on site and are not freely available commercially (see Chapter “Application notes”).

1.4 Basic information on EMC

The term EMC covers both electromagnetic emission and electromagnetic susceptibility (

Figure 1).

EMC

Emission Susceptibility

EME

EMS

source equipment

conducted

radiated

Disturbed Interference Propagation

SSB0007-3-E

Figure 1 EMC terms

EMC = Electromagnetic compatibility EME = Electromagnetic emission EMS = Electromagnetic susceptibility CE = Conducted emission CS = Conducted susceptibility RE = Radiated emission RS = Radiated susceptibility

An interference source may generate conducted or radiated electromagnetic energy, i.e. conducted emission (CE) or radiated emission (RE). This also applies to the electromagnetic susceptibility of disturbed equipment.

In order to work out cost-efficient solutions, all phenomena must be considered, and not just one aspect such as conducted emission.

Please read Important notes and Cautions and warnings.

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General

EMC basics

EMC components are used to reduce conducted electromagnetic interferences to the limits defined in an EMC plan or below the limits specified in the EMC standards (

Figure 2). These components

may be installed either in the source or in the disturbed equipment.

Filter

Source

Interference currents

Interference voltages

Control line

Power supply

RE Magnetic field

Electric field

Electromagnetic field

Disturbed

equip-

ment

Signal line

SSB1685-G-E

Figure 2 Susceptibility model and filtering

EPCOS offers EMC components with a wide range of rated voltages and currents for power lines as well as for signal and control lines.

Please read Important notes and Cautions and warnings.

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General

EMC basics

1.5 Interference sources and disturbed equipment

Interference source

An interference source is an electrical equipment which emits electromagnetic interferences. We can differentiate between two main groups of interference sources corresponding to the type of frequency spectrum emitted (

Interference sources with discrete frequency spectra (e.g. high-frequency generators and microprocessor systems) emit narrowband interferences.

Switchgear and electric motors in household appliances, however, spread their interference energy over broad frequency bands and are considered to belong to the group of interference sources having a continuous frequency spectrum.

Figure 3).

Interference source (emission)

Discrete frequency spectrum

(Sine-wave, low energy)

μP systems RF generators Medical equipment Data processing systems Microwave equipment Ultrasonic equipment RF welding apparatus Radio and TV receivers Switch-mode power supplies Frequency converters UPS systems Electronic ballasts

Figure 3 Interference sources

Please read Important notes and Cautions and warnings.

Continuous frequency spectrum

(Impulses, high energy)

Switchgear (contactors, relays) Household appliances Gas discharge lamps Power supplies and battery chargers Frequency converters Ignition systems Welding apparatus Motors with brushes Atmospheric discharges

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General

EMC basics

Disturbed equipment

Electrical equipment or systems subject to interferences and which can be adversely affected by it are termed disturbed equipment.

In the same way as interference sources, disturbed equipment can also be categorized corresponding to frequency characteristics. A distinction can be made between narrowband and broadband susceptibility (

Narrowband systems include radio and TV sets, for example, whereas data processing systems are generally characterized as broadband systems.

Figure 4).

Disturbed equipment (susceptibility)

Narrowband susceptibility Broadband susceptibility

Radio and TV receivers Radio reception equipment Modems Data transmission systems Radio transmission equipment Remote-control equipment Cordless and cellular phones

Figure 4 Disturbed equipment

Please read Important notes and Cautions and warnings.

Digital and analog systems Data processing systems Process control computers Control systems Sensors Video transmission systems Interfaces

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General

EMC basics

1.6 Propagation of interferences

Interference voltages and currents can be grouped into common-mode interferences, differentialmode interferences and unsymmetrical interferences:

(a)

Common-mode Differential-mode Unsymmetrical

propagation propagation propagation

(b)

(c)

us1 Vus2

SSB1465-P-E

Figure 5 Propagation modes

 5 (a)

Common-mode interferences (asymmetrical interferences): – occurs between all lines in a cable and reference potential; – occurs mainly at high frequencies (approximately 1 MHz upwards).

 5 (b)

Differential-mode interferences (symmetrical interferences): – occurs between two lines (L-L, L-N); – occurs mainly at low frequencies (up to several hundred kHz).

 5 (c)

Unsymmetrical interferences: – This term is used to describe interferences between one line and the reference potential.

Please read Important notes and Cautions and warnings.

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General

EMC basics

1.7 Characteristics of interferences

In order to be able to choose the correct EMC measures, we need to know the characteristics of the interferences, how they are propagated and the coupling mechanisms. In principle, the interferences can also be classified according to their propagation mode (

Figure 6). At low frequencies, it can be assumed that the interferences only spreads along conductive structures, at high frequencies virtually only by means of electromagnetic radiation. In the MHz frequency range, the term coupling is generally used to describe the mechanism.

Analogously, conducted interferences at frequencies of up to several hundred kHz is mainly differential-mode (symmetrical), at higher frequencies, it is common-mode (asymmetrical). This is be- cause the coupling factor and the effects of parasitic capacitance and inductance between the conductors increase with frequency.

X capacitors and single chokes offer effective differential-mode insertion loss. Common-mode interferences can be reduced by current-compensated chokes and Y capacitors. However, this requires a well-designed EMC-compliant grounding and wiring system.

The categorization of types of interference and suppression measures and their relation to the frequency ranges is reflected in the frequency limits for interference voltage and interference field strength measurements.

SSB1466-X-E

Differential mode

Common mode

Field

Interference characteristic

Line

X cap

Pc ch.

Coupling

Y cap

CC ch.

Ground

Interference voltage

Figure 6 Frequency range overview

Pc ch. = Iron powder core chokes, but also all single chokes X cap = X capacitors Cc ch. = Current-compensated chokes Y cap = Y capacitors

Please read Important notes and Cautions and warnings.

Field

Shielding

Field strength

102 MHz 10

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Interference propagation

Remedies

Limits

General

EMC basics

1.8 EMC measurement methods

As previously mentioned, an interference source causes both conducted and radiated electromagnetic interferences.

Propagation along lines can be detected by measuring the interference current and the interference voltage (

Figure 7).

The effect of interference fields on their immediate vicinity is assessed by measuring the magnetic and electric fields. This kind of propagation is also frequently termed electric or magnetic coupling (near field).

In higher frequency ranges, characterized by the fact that equipment dimensions are in the order of magnitude of the wavelength under consideration, the interference energy is mainly radiated directly (far field). Conducted and radiated propagation must also be taken into consideration when testing the susceptibility of disturbed equipment.

Interference sources, such as sine-wave generators as well as pulse generators with a wide variety of pulse shapes are used for such tests.

Power supply

Line impedance stabilization

network

Measuring receiver Spectrum analyzer Storage oscilloscope Transient recorder

Current probe

Voltage probe

Rod antenna

int

Broadband dipole antenna

Measuring receiver

int

Source

int

Loop antenna

Near field coupling

Measuring receiver

SSB0016-2-E

Figure 7 Propagation of electromagnetic interferences and EMC measurement methods

= Magnetic interference fields

int

= Electrical interference fields

int

= Electromagnetic interference fields (radiated emission)

int

= Interference current

int

= Interference voltage

int

Please read Important notes and Cautions and warnings.

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General

EMC basics

1.9 EMC standards

New, harmonized European standards have been issued in conjunction with the EU’s EMC Directive or national EMC legislation. These specify measurement methods and limits or test levels for both the emissions and immunity of electrical equipment, installations and systems.

The subdivision of the European standards into various categories (see following table) makes it easier to find the rules that apply to the respective equipment. The generic standards always apply to all equipment for which there is no specific product family standard or dedicated product stan- dard. The basic standards contain information on interference phenomena and general measuring methods.

The following standards and regulations form the framework of the conformity tests:

EMC standards Germany Europe International

Generic standards

define the EMC environment in which a device is to operate according to its intended use.

Emissionresidential

industrial

Immunityresidential

industrial

DIN EN 61000-6-3 DIN EN 61000-6-4

DIN EN 61000-6-1 DIN EN 61000-6-2

EN 61000-6-3 EN 61000-6-4

EN 61000-6-1 EN 61000-6-2

IEC 61000-6-3 IEC 61000-6-4

IEC 61000-6-1 IEC 61000-6-2

Basic standards

describe physical phenomena and measurement methods.

Measuring equipment DIN EN 55016-1-x EN 55016-1-x CISPR 16-1-x Measuring methodsemission

immunity

Harmonics Flicker

DIN EN 55016-2-x DIN EN 61000-4-1

DIN EN 61000-3-2 DIN EN 61000-3-3

EN 55016-2-x EN 61000-4-1

EN 61000-3-2 EN 61000-3-3

CISPR 16-2-x IEC 61000-4-1

IEC 61000-3-2 IEC 61000-3-3

Immunity parameters e.g. ESD

EM fields Burst Surge Induced RF fields Magnetic fields Voltage dips

DIN EN 61000-4-2 DIN EN 61000-4-3 DIN EN 61000-4-4 DIN EN 61000-4-5 DIN EN 61000-4-6 DIN EN 61000-4-8 DIN EN 61000-4-11

EN 61000-4-2 EN 61000-4-3 EN 61000-4-4 EN 61000-4-5 EN 61000-4-6 EN 61000-4-8 EN 61000-4-11

IEC 61000-4-2 IEC 61000-4-3 IEC 61000-4-4 IEC 61000-4-5 IEC 61000-4-6 IEC 61000-4-8 IEC 61000-4-11

Please read Important notes and Cautions and warnings.

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General

EMC basics

EMC standards Germany Europe International

Product family standards

define limit values for emission and immunity.

ISM equipment emission

immunity

Household appliances emission

immunity

Lighting emission

immunity

Radio and TV emission equipment immunity

DIN EN 55011

DIN EN 55014-1 DIN EN 55014-2

DIN EN 55015 DIN EN 61547

DIN EN 55013 DIN EN 55020

EN 55011

EN 55014-1 EN 55014-2

EN 55015 EN 61547

EN 55013 EN 55020

CISPR 11

CISPR 14-1 CISPR 14-2

CISPR 15 IEC 1547

CISPR 13

CISPR 20 High-voltage systems emission DIN VDE 0873 — CISPR 18 ITE equipment

Vehicles emission

emission immunity

immunity

DIN EN 55022 DIN EN 55024

DIN EN 55025 —

EN 55022 EN 55024

EN 55025

CISPR 22

CISPR 24

CISPR 25

ISO 11451

ISO 11452

The following table shows the most important standards concerning immunity.

Standard Test characteristics Phenomena

Conducted interferences

EN 61000-4-4 IEC 61000-4-4

EN 61000-4-5 IEC 61000-4-5

5/50 ns (single impulse)

2.5 kHz, 5 kHz or 100 kHz burst

1.2/50 μs (open-circuit voltage) 8/20 μs (short-circuit current)

Burst Cause: switching processes

Surge (high-energy transients) Cause: lightning strikes mains supply, switching processes

EN 61000-4-6 IEC 61000-4-6

1; 3; 10 V 150 kHz to 80 MHz (230 MHz)

High-frequency coupling Narrow-band interferences

Radiated interferences

EN 61000-4-3 IEC 61000-4-3

EN 61000-4-8 IEC 61000-4-8

1) Is governed by the safety and quality standards of the product families.

2) The EU Automotive Directive (95/54/EC) also covers limits and immunity requirements.

3) Some equipment is covered by the R & TTE Directive (Radio- and Telecommunications Terminals).

Please read Important notes and Cautions and warnings.

3; 10 V/m 80 to 1000 MHz

up to 100 A/m 50 Hz

High-frequency interference fields

Magnetic interference fields with power-engineering frequency

01/06 11

General

EMC basics

Standard Test characteristics Phenomena

Electrostatic discharge (ESD)

EN 61000-4-2

to 15 kV Electrostatic discharge

IEC 61000-4-2

Instability of the supply voltage

EN 61000-4-11 IEC 61000-4-11

e.g. 40 % V 0 % V

e.g. 40 % V (2 s reduction, 1 s reduced voltage,

for 1 … 50 periods

for 0,5 periods

or 0 % V

Voltage dips Short-term interruptions

Voltage variations

2 s increase)

1.10 Propagation of conducted interferences

In order to be able to select suitable EMC components, the way in which conducted interferences are propagated needs to be known.

A floating interference source primarily emits differential-mode interferences which are propagated along the connected lines. The interference current will flow towards the disturbed equipment on one line and away from it on the other line, just as the mains current does.

Differential-mode interferences occur mainly at low frequencies (up to several hundred kHz).

Interference Disturbed

source equipment

Common-mode interference current

Differential-mode interference current

: Parasitic capacitance

SSB0022B-E

Figure 8 Common-mode and differential-mode interferences

However, parasitic capacitances in interference sources and disturbed equipment or intended ground connections, also lead to an interference current in the ground circuit. This common-mode interference current flows towards the disturbed equipment through both the connecting lines and returns to the interference source through ground. Since the parasitic capacitances will tend towards representing a short-circuit with increasing frequencies and the coupling effects the connecting cables and the equipment itself will increase correspondingly, common-mode interferences become dominant above some MHz.

Please read Important notes and Cautions and warnings.

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General

EMC basics

In Europe, the term of an “unsymmetrical interference” is used to describe the interference voltage between one line and a reference potential. It consists of symmetrical and asymmetrical parts.

EPCOS specifies characteristic values of insertion loss for the individual filter types in order to facilitate the selection of suitable EMC filters.

1.11 Filter circuits and line impedance

EMC filters are virtually always designed as reflecting lowpass filters, i.e. they reach their highest insertion loss when they are – on the one hand – mismatched to the impedance of the interference source and disturbed equipment and – on the other hand – mismatched to the impedance of the line. Possible filter circuits for various impedance conditions are shown in

Figure 9.

It is, therefore, necessary to find out the impedances so that optimum filter circuit designs as well as economical solutions can be implemented.

The impedances of the power networks under consideration are usually known from calculations and extensive measurements, whereas the impedances of interference sources or disturbed equipment are, in most cases, not or only inadequately known.

For this reason, it is impossible to design the most suitable filter solution without EMC tests. In this context, we offer our customers the competent consulting of our skilled staff, both on-site and in our EMC laboratory in Regensburg (see also “EMC services”, Section 7, “EMC laboratory”).

Line Impedance of impedance source of interference/disturbed equipment

low high

high high

high high unknown

low low

low low unknown

unknown

Figure 9 Filter circuits and impedance relationships

Please read Important notes and Cautions and warnings.

SSB0042-Q-E

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General

Selection criteria

2 Selection criteria for EMC filters

To comply with currently valid regulations, a frequency range of 150 kHz to 1000 MHz has to be taken into consideration, in most cases, in order to ensure electromagnetic compatibility; in addition, however, further aspects such as low-frequency phenomena should be considered.

EMC filters must thus have good RF characteristics and are ususally required to be effective over a broad frequency range.

 For individual components (inductors, capacitors) the RF characteristics are specified by stating

the impedance as a function of frequency.

 The insertion loss is used as a criterion for selecting EMC filters (see Section 3.1.17).

If the device under test (DUT) is terminated on both sides with an ohmic impedance of 50 Ω, for example, the result of the measurement is referred to as being the 50-Ω insertion loss.

Depending on the particular application intended, priorities for consideration of the three possible kinds of insertion loss

 common-mode (asymmetrical)  differential-mode (symmetrical) or  unsymmetrical

must be decided upon. The measuring method for 50-Ω insertion loss has been adapted from the field of communications

engineering and is also specified in the relevant national and international standards. Although it permits a comparison of different filters, it provides only little information on the efficiency

in practical applications. The reason is – as already mentioned in the previous section – that neither the interference source

or disturbed equipment nor the connected power line system will have an ohmic impedance of 50 Ω at frequencies below 1 MHz.

Likewise, the attenuation of interference pulses cannot simply be determined on the basis of the insertion loss curve. In this case, it is also necessary to take the non-linear response of the EMC chokes in the filters into consideration.

We can quote filter-specific values on request if you send us the pulse shapes in question.

Please read Important notes and Cautions and warnings.

01/06 14

General

Terms and definitions

3 Terms and definitions

3.1 Electrical characteristics

3.1.1 Rated voltage V

The rated voltage VR is either the maximum RMS operating voltage at the rated frequency or the highest DC operating voltage which may be continuously applied to the filter at temperatures between the lower category temperature T

and the upper category temperature T

min

. Filters which

max

are rated for a frequency of 50/60 Hz may also be operated at DC voltages.

3.1.2 Nominal voltage V

The nominal voltage VN is the voltage which designates a network or electrical equipment and to which specific operating characteristics are referred.

IEC 60038 defines the most widely used nominal voltages for public supply networks (e.g. 230/400 V, 277/480 V, 400/690 V). It is recommended that the voltage at the transfer points should not deviate from the nominal voltage by more than ±10% under normal network conditions.

3.1.3 Difference between rated and nominal voltage

For filters, the rated voltage is defined as a reference parameter. It specifies the maximum voltage at which the filter can be continuously operated (see Section 3.1.1). This voltage must never be exceeded, as otherwise damage may occur.

Only small deviations are tolerated, such as may occur when a filter with a rated voltage of 250 V is operated at in a network with a nominal voltage of 230 V (230 V +10% = 253 V). This relationship is shown in

250

240

230

220

Figure 10.

Filter Network

Rated voltage Nominal voltage V

R N

253 (VN +10 %)

210

200

Figure 10 Difference between rated and nominal voltage

Please read Important notes and Cautions and warnings.

01/06 15

SSB1592-S-E

207 (V

10 %)

General

Terms and definitions

When EMC filters and other EMC components are selected, care shall be taken to ensure that the maximum line voltage in each case, e.g. V mitted according to EN 133200.

+10%, is not exceeded. Short voltage surges are per-

3.1.4 Network types

The filters are approved for various network types (e.g. TN, TT, IT networks). They are described in Section 7 “Power distribution systems”.

3.1.5 Test voltage V

The test voltage V

test

is the AC or DC voltage which may be applied to the filter for the specified test

test

duration at the final inspection (100% test). If necessary, we recommend a single repetition of the test at a maximum of 80% of the specified voltage. The rate of voltage rise or fall must then not exceed 500 V/s. The time shall be measured as soon as 90% of the test voltage permissible for the repeat test has been reached. During the test, no dielectric breakdown may occur (the insulation would no longer limit the current flow). Healing effects of the capacitors are permissible.

3.1.6 Rated current I

The rated current IR is the maximum AC or DC current at which the filter can be continuously operated under nominal conditions.

Above the rated temperature T the derating curves (see Section 10).

, the operating current shall as a rule be reduced in accordance with

For 2 and 3-line filters, the rated current is specified for the simultaneous flow of a current of this value though all the lines. For 4-line filters (e.g. filters with three phase lines and one neutral line), the sum current of the neutral line is assumed to be close to zero.

Higher thermal loads may occur during AC operation due to non-sinusoidal waveforms. These must be taken into account where necessary.

The temperature rise of the EMC filters at rated current and temperature is tested with a connection via test cross-sections as specified in UL 508:Aug 22, 2000 "Industrial Control Equipment", Table

43.2, Table 43.3 (broadly similar to EN 60947:1999).

3.1.7 Overload capability

The rated current may be exceeded for a short time. Details of permissible currents and load durations are specified in the various data sheets.

3.1.8 Pulse handling capability

Saturation effects (e.g in the ferrite cores used) may occur when high-energy pulses are applied to the components and these may lead to impaired interference suppression. The maximum permissible voltage-time integral area is used to characterize the pulse handling capability of chokes and filters. For standard components a range from 1 to 10 mVs can be assumed. More specific data can be obtained upon request.

Please read Important notes and Cautions and warnings.

01/06 16

General

Terms and definitions

3.1.9 Current derating I/I

At ambient temperatures above the rated temperature stated in the data sheet, the operating current of chokes and filters must be reduced according to the derating curve (see Section 10).

3.1.10 Rated inductance L

The rated inductance LR is the inductance which has been used to designate the choke, as measured at the frequency f

3.1.11 Stray inductance L

The stray inductance L

stray

(also termed leakage inductance) is the inductance measured through

stray

both coils when a current-compensated choke is short-circuited at one end. This affects differentialmode interferences.

stray

SSB1593-L-E

Figure 11 Stray inductance

3.1.12 Inductance decrease ΔL/L

The inductance decrease ΔL/L0 is the drop in inductance at a given current relative to the initial inductance L

measured at zero current. The data sheets specify this as a percentage. This de-

crease is caused by the magnetization of the core material, which is a function of the field strength, as induced by the operating current. Generally the decrease is less than 10%.

, R

3.1.13 DC resistance R

typ

min

, R

max

The DC resistance is the resistance of a line as measured using direct current at a temperature of 20 °C, whereby the measuring current must be kept well below the rated current.

typical value

typ

minimum value

min

maximum value

max

3.1.14 Winding capacitance, parasitic capacitance C

Parasitic capacitances Cp, which impair the RF characteristics of the filters, are related to the filter geometry. These capacitances may affect the lines mutually (differential-mode) as well as the lineto-ground circuit (common-mode). The design of all EMC filters supplied by EPCOS minimizes the parasitic effects. Due to this, our filters have excellent interference suppression characteristics right up to high frequencies.

Please read Important notes and Cautions and warnings.

01/06 17

General

Terms and definitions

3.1.15 Quality factor Q

The quality factor Q is the quotient of the imaginary part of the impedance divided by the real part, measured at frequency f

3.1.16 Measuring frequencies f

, f

fQ is the frequency for which the quality factor Q of a choke is specified.

is the frequency at which the inductance of a choke is measured.

3.1.17 Insertion loss

The insertion loss is a measure for the efficiency of EMC components, as measured by using a standardized test setup (

Figure 12).

Reference measurement

Z 1

V=V=V

20 10

2Z =2

Z = 50

Ω α

DUT

11 A21

A =

12 A22

= 20 log

V2 = V

A11(ω) =V

Insertion loss measurement

= 20 log

SSB1464-G-E

()

Figure 12 Definition of insertion loss

The input terminals of the device (circuit) are connected to an RF generator with impedance Z (usually 50 Ω) . At the output of the component, the voltage is measured using an RF voltmeter having the same impedance Z. The insertion loss is then calculated from the quotient of half the open-circuit generator voltage V

and the filter output voltage V

Please read Important notes and Cautions and warnings.

01/06 18

General

Terms and definitions

Test setups for insertion loss measurement used for EMC filters

a) Differential mode (symmetrical insertion loss measurement)

Transmitter Filter Receiver

50 Ω

1:1

50 Ω

Figure 13 Symmetrical insertion

loss measurement to CISPR 17 (1981) Fig. B5

Insertion loss α = 20 lg

------------2 ⋅ V

[dB]

SSB0183-Y-E

b) Common mode (asymmetrical measurement, branches connected in parallel)

Transmitter Filter Receiver

50 Ω

Figure 14 Asymmetrical measurement

to CISPR 17 (1981) Fig. B6

SSB0184-7-E

Common-mode measurement with lines connected in parallel is widely used in the United States. Some diagrams in this data book show the results of this measurement in addition to those obtained according to a) and c).

Please read Important notes and Cautions and warnings.

01/06 19

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Epcos EMC filters General Product Line Information

Specifications and Main Features

Frequently Asked Questions

User Manual