EN IEC 61308:2026
(Main)High-frequency dielectric heating installations - Test methods for the determination of power output
- Abstract
This document specifies test methods for the determination of useful high frequency power output in equipment for industrial heating and processing of materials. It is in particular applicable to HF generators made available to users as separate units.
This document is basically applicable to equipment operating in the frequency range 100 kHz to 300 MHz, as defined in IEC 60519-1, with the following limitations.
– This document does not apply to induction heating, which it is possible to carry out in the lower part of the specified frequency band.
– The ISM centre frequencies for dielectric heating and processing of industrial interest are narrow bands about 6,78 MHz, 13,56 MHz, 27,12 MHz and 40,68 MHz.
– This document is not applicable to:
• appliances for household and similar use;
• commercial use;
• laboratory use;
• medical high frequency equipment.
For equipment working in designated ISM bands, it is a legal requirement that the frequency remains within the ISM bands according to CISPR 11, but the resonant frequency of the circuit varies with the change of dielectric parameters of the load. Therefore, the value of the mean output power in the work cycle can be much lower than the value obtained under the test conditions. This value depends upon the response of the tuning system.
NOTE 1 The following criteria are suitable for determination of the classification as industrial equipment:
– commercial equipment is typically designed and planned for series production of many identical units;
– industrial equipment is typically produced in small series or even as single units; the processed goods are consumed or ready for final use at the end of the heating process.
NOTE 2 Heating a workload with dielectric parameters which change significantly in time and/or with temperature, the value of the output power obtained with the actual charge can be different from that obtained with the test load specified in this document.
This document relates to equipment normally operating under continuous rated conditions.
- Status
- Published
- Publication Date
- 17-Sep-2026
- Technical Committee
- CLC/SR 27 - Industrial electroheating equipment
- Current Stage
- 6060 - Document made available - Publishing
- Start Date
- 18-Sep-2026
- Due Date
- 19-Dec-2025
- Completion Date
- 18-Sep-2026
EN IEC 61308:2026 is a CENELEC European Standard that specifies test methods for determining the power output of high-frequency dielectric heating installations. It is aimed at industrial heating and processing equipment, especially HF generators supplied as separate units, and it also covers output evaluation for certain high-frequency dielectric plastic welders and type B equipment.
What does EN IEC 61308:2026 specify?
EN IEC 61308:2026 specifies how to measure the useful high-frequency power output of industrial dielectric heating installations under defined test conditions. The document is written for equipment that normally operates under continuous rated conditions, with scope limits for other application areas.
The standard is organized into:
- Clause 1 - Scope
- Clause 2 - Normative references
- Clause 3 - Terms and definitions
- Clause 4 - Test loads
- Clause 5 - Description of tests
- Annex A - Recommended test circuit for the lamp-load method
| Annex | What it covers |
|---|---|
| Annex A | Recommended test circuit for the lamp-load method |
In practice, this structure helps users go from the equipment type, to the test load, to the actual measurement method and calculation.
What are the key requirements of EN IEC 61308:2026?
EN IEC 61308:2026 centers on matching the test load to the equipment and then measuring output power with a method suited to that load. The main practical point is that the test should represent the normal working load as closely as possible, because the result is used to judge generator output and, for some equipment, installation output.
Test loads and when to use them
Clause 4 identifies four test load families:
- Calorimetric load - a substitute load for measuring generator output when the power is around the higher end of the low-power range and the load can be matched by impedance.
- Lamp load - a group of incandescent lamps used for lower-power measurements when the generator terminals are accessible.
- Matched resistive load - a low-reactance resistor connected directly to the high-frequency output terminals.
- Wet-sand load - a sand-and-water charge that simulates a normal load for some type B equipment.
This matters because the chosen load determines whether the measured power reflects the generator, the applicator, or the full installation.
Calorimetric load method
Clause 5.2 gives a water-based calorimetric method. EN IEC 61308:2026 requires the load to be matched without major changes to tuning, and it asks the operator to control water flow, mixing, inlet and outlet temperature, and thermal equilibrium.
In practice, this method is useful when the generator output can be coupled to a water-absorbing substitute load and the user wants a repeatable power reading with good accuracy. The standard also says the measuring devices should not be disturbed by high-frequency fields, so the setup and instrument placement matter.
Lamp-load temperature method
Clause 5.3 describes a lamp-load method based on incandescent lamps and comparison of lamp temperature with a mains-frequency reference lamp. EN IEC 61308:2026 says this method needs accessible output terminals, short low-inductance leads, and lamps chosen to suit the rated power of the equipment.
This method is mainly practical for lower-frequency and lower-power cases. The document also notes that it becomes unsuitable at higher frequencies, so readers should use it only where the lamp circuit and the frequency range make the result meaningful.
Matched resistive load method
Clause 5.4 allows a low-reactance resistive load cooled by air or water, often connected through a coaxial feeder. EN IEC 61308:2026 treats this as a straightforward electrical power measurement method, using current or voltage at the resistor.
This is the simplest route when the generator can drive a suitable resistor directly. It is especially useful for test laboratories and equipment makers who need a direct electrical check of output power.
Wet-sand load method
Clause 5.5 uses a wet-sand load placed in the applicator, mainly for some type B equipment. EN IEC 61308:2026 has the user weigh the load before and after heating and then calculate power from the water loss and heating time.
In practice, this method is less precise than the other load methods, but it is useful where the output terminals cannot be measured directly and the normal applicator must be part of the test.
Plastic welders and type B equipment
Clause 5.6 addresses high-frequency dielectric plastic welders. If the generator output terminals are accessible, EN IEC 61308:2026 allows measurement by the calorimetric, lamp-load, or matched resistive methods. If the terminals are not accessible, the document provides a plastic-material test using the specified cutting-edge welding electrode.
Clause 5.7 then covers type B equipment, where direct output measurement is not possible. The standard uses a calculation based on the manufacturer’s tube or circuit data and the estimated efficiency of the high-frequency circuit.
For buyers and quality managers, this is important because it shows that some equipment is checked by direct measurement and others by calculated output tied to the actual machine configuration.
What terms does EN IEC 61308:2026 define?
EN IEC 61308:2026 defines the terms needed to distinguish equipment types, loads, and the measured output.
- Type A equipment - high-frequency equipment where the generator is separate from, or separable from, the applicator.
- Type B equipment - high-frequency equipment where the generator is directly coupled to the applicator.
- Useful output power - for type A equipment, the maximum power measured in a test load.
- Useful output power - for type B equipment, the high-frequency power developed in the normal load.
- Calorimetric load - a substitute load used to measure output by heat transfer to water.
- Lamp load - a load made from incandescent lamps used for temperature-based comparison.
- Matched resistive load - a low-reactance resistor used to take direct electrical measurements.
- Plastic welding test electrode - the defined cutting-edge welding electrode used for the plastic-material test.
Who uses EN IEC 61308:2026?
EN IEC 61308:2026 is used by manufacturers of high-frequency dielectric heating equipment, test laboratories, and conformity assessment bodies that need to verify output power. It is also relevant to quality managers, engineering teams, and buyers who need to compare installations, check rated output claims, or specify a test method for acceptance.
The document is especially relevant in industrial electroheating, electromagnetic processing, and high-frequency plastic welding.
What changed in EN IEC 61308:2026 from the previous edition?
EN IEC 61308:2026 supersedes EN 61308:2006 and its amendments and corrigenda. The IEC foreword says this third edition is a technical revision.
The stated changes are:
- alignment with the more recent principles in IEC 60519-1 and IEC 60519-6
- more detailed descriptions of the calorimetric load test
- more detailed output power evaluation for dielectric plastic welders
Which standards are used with EN IEC 61308:2026?
EN IEC 61308:2026 refers to these publications in its normative references and annex mapping:
- IEC 60050-841 - provides the vocabulary for industrial electroheat
- IEC 60519-1 - gives the general safety requirements for electroheating and electromagnetic processing installations
- IEC 60519-6 - gives the particular safety requirements for high-frequency dielectric and microwave heating and processing equipment
These references matter because they provide the vocabulary and safety framework used when applying the test methods.
What does the EN IEC 61308:2026 document contain?
EN IEC 61308:2026 contains both method descriptions and supporting figures for practical test setups. The figures show example calorimeter loads, a short tubular calorimeter load, the lamp-load circuit, an example lamp load, detail of the lamp load, and the plastic welding test electrode.
It also includes formulas for power calculation, instructions for water-based and lamp-based measurements, and guidance for matching the test load to the equipment. Annex A gives a recommended test circuit for the lamp-load method using a photoelectric cell and a calibration curve approach. In practice, the document supports design verification, test-lab measurements, and output-power assessment for industrial installations and plastic welders.
Relations
- Effective Date
- 18-Feb-2025
- Effective Date
- 01-Sep-2026
- Effective Date
- 01-Sep-2026
- Effective Date
- 01-Sep-2026
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Frequently Asked Questions
EN IEC 61308:2026 is a standard published by CLC. Its full title is "High-frequency dielectric heating installations - Test methods for the determination of power output". This standard covers: This document specifies test methods for the determination of useful high frequency power output in equipment for industrial heating and processing of materials. It is in particular applicable to HF generators made available to users as separate units. This document is basically applicable to equipment operating in the frequency range 100 kHz to 300 MHz, as defined in IEC 60519-1, with the following limitations. – This document does not apply to induction heating, which it is possible to carry out in the lower part of the specified frequency band. – The ISM centre frequencies for dielectric heating and processing of industrial interest are narrow bands about 6,78 MHz, 13,56 MHz, 27,12 MHz and 40,68 MHz. – This document is not applicable to: • appliances for household and similar use; • commercial use; • laboratory use; • medical high frequency equipment. For equipment working in designated ISM bands, it is a legal requirement that the frequency remains within the ISM bands according to CISPR 11, but the resonant frequency of the circuit varies with the change of dielectric parameters of the load. Therefore, the value of the mean output power in the work cycle can be much lower than the value obtained under the test conditions. This value depends upon the response of the tuning system. NOTE 1 The following criteria are suitable for determination of the classification as industrial equipment: – commercial equipment is typically designed and planned for series production of many identical units; – industrial equipment is typically produced in small series or even as single units; the processed goods are consumed or ready for final use at the end of the heating process. NOTE 2 Heating a workload with dielectric parameters which change significantly in time and/or with temperature, the value of the output power obtained with the actual charge can be different from that obtained with the test load specified in this document. This document relates to equipment normally operating under continuous rated conditions.
This document specifies test methods for the determination of useful high frequency power output in equipment for industrial heating and processing of materials. It is in particular applicable to HF generators made available to users as separate units. This document is basically applicable to equipment operating in the frequency range 100 kHz to 300 MHz, as defined in IEC 60519-1, with the following limitations. – This document does not apply to induction heating, which it is possible to carry out in the lower part of the specified frequency band. – The ISM centre frequencies for dielectric heating and processing of industrial interest are narrow bands about 6,78 MHz, 13,56 MHz, 27,12 MHz and 40,68 MHz. – This document is not applicable to: • appliances for household and similar use; • commercial use; • laboratory use; • medical high frequency equipment. For equipment working in designated ISM bands, it is a legal requirement that the frequency remains within the ISM bands according to CISPR 11, but the resonant frequency of the circuit varies with the change of dielectric parameters of the load. Therefore, the value of the mean output power in the work cycle can be much lower than the value obtained under the test conditions. This value depends upon the response of the tuning system. NOTE 1 The following criteria are suitable for determination of the classification as industrial equipment: – commercial equipment is typically designed and planned for series production of many identical units; – industrial equipment is typically produced in small series or even as single units; the processed goods are consumed or ready for final use at the end of the heating process. NOTE 2 Heating a workload with dielectric parameters which change significantly in time and/or with temperature, the value of the output power obtained with the actual charge can be different from that obtained with the test load specified in this document. This document relates to equipment normally operating under continuous rated conditions.
EN IEC 61308:2026 is classified under the following ICS (International Classification for Standards) categories: 25.180.10 - Electric furnaces. The ICS classification helps identify the subject area and facilitates finding related standards.
EN IEC 61308:2026 has the following relationships with other standards: It is inter standard links to EN 61308:2006, EN IEC 60519-6:2024, IEC 60050-841:2004, EN IEC 60519-1:2020. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN IEC 61308:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2026
Nadomešča:
SIST EN 61308:2006
Inštalacije za visokofrekvenčno dielektrično segrevanje - Preskusne metode za
ugotavljanje izhodne moči (IEC 61308:2026)
High-frequency dielectric heating installations - Test methods for the determination of
power output (IEC 61308:2026)
Hochfrequente dielektrische Erwärmungsanlagen - Prüfverfahren für die Bestimmung
der Ausgangsleistung (IEC 61308:2026)
Installations de chauffage diélectrique à haute fréquence - Méthodes d'essai pour la
détermination de la puissance de sortie (IEC 61308:2026)
Ta slovenski standard je istoveten z: EN IEC 61308:2026
ICS:
25.180.10 Električne peči Electric furnaces
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 61308
NORME EUROPÉENNE
EUROPÄISCHE NORM September 2026
ICS 25.180.10 Supersedes EN 61308:2006
English Version
High-frequency dielectric heating installations - Test methods for
the determination of power output
(IEC 61308:2026)
Installations de chauffage diélectrique à haute fréquence - Hochfrequente dielektrische Erwärmungsanlagen -
Méthodes d'essai pour la détermination de la puissance de Prüfverfahren für die Bestimmung der Ausgangsleistung
sortie (IEC 61308:2026)
(IEC 61308:2026)
This European Standard was approved by CENELEC on 2026-09-10. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61308:2026 E
European foreword
The text of document 27/1244/FDIS, future edition 3 of IEC 61308, prepared by TC 27 "Industrial
electroheating and electromagnetic processing" was submitted to the IEC-CENELEC parallel vote and
approved by CENELEC as EN IEC 61308:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-09-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-09-30
document have to be withdrawn
This document supersedes EN 61308:2006 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61308:2026 was approved by CENELEC as a European
Standard without any modification.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60050-841 - International Electrotechnical Vocabulary - - -
Part 841: Industrial electroheat
IEC 60519-1 - Safety in installations for electroheating EN IEC 60519-1 -
and electromagnetic processing - Part 1:
General requirements
IEC 60519-6 - Safety in installations for electroheating EN IEC 60519-6 -
and electromagnetic processing - Part 6:
Particular requirements for high frequency
dielectric and microwave heating and
processing equipment
IEC 61308 ®
Edition 3.0 2026-08
INTERNATIONAL
STANDARD
High-frequency dielectric heating installations - Test methods for the
determination of power output
ICS 25.180.10 ISBN 978-2-8327-1430-0
IEC 61308:2026-08(en)
IEC 61308:2026 © IEC 2026
CONTENTS
FOREWORD . 2
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 5
4 Test loads . 5
4.1 General . 5
4.2 Calorimetric load . 6
4.3 Lamp load . 6
4.4 Matched resistive load . 6
4.5 Wet-sand load. 6
5 Description of tests . 6
5.1 General . 6
5.2 Calorimetric load method . 6
5.3 Lamp-load temperature method . 9
5.4 Matched resistive load method . 11
5.5 Wet-sand load method . 11
5.6 Evaluation of the output power for high-frequency dielectric plastic welders . 12
5.6.1 General . 12
5.6.2 Test with plastic material . 12
5.7 Evaluation of the output power for type B equipment . 13
Annex A (informative) Recommended test circuit for the lamp-load method . 14
Figure 1 – Example of a calorimeter load . 8
Figure 2 – Example of a short tubular calorimeter load . 9
Figure 3 – Lamp-load circuit . 9
Figure 4 – Example of a lamp load . 10
Figure 5 – Detail of the lamp load . 11
Figure 6 – Plastic welding test electrode . 13
Figure A.1 – Recommended test circuit for the lamp-load method . 14
IEC 61308:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
High-frequency dielectric heating installations -
Test methods for the determination of power output
FOREWORD
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all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61308 has been prepared by IEC technical committee 27: Industrial electroheating and
electromagnetic processing. It is an International Standard.
This third edition cancels and replaces the second edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) adaptation and alignment to the principles in more recent editions of IEC 60519-1 and
IEC 60519-6;
b) more detailed descriptions of, in particular, the calorimetric load test and output power
evaluation for dielectic plastic welders.
IEC 61308:2026 © IEC 2026
The text of this International Standard is based on the following documents:
Draft Report on voting
27/1244/FDIS 27/1248/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 61308:2026 © IEC 2026
1 Scope
This document specifies test methods for the determination of useful high frequency power
output in equipment for industrial heating and processing of materials. It is in particular
applicable to HF generators made available to users as separate units.
This document is basically applicable to equipment operating in the frequency range 100 kHz
to 300 MHz, as defined in IEC 60519-1, with the following limitations.
– This document does not apply to induction heating, which it is possible to carry out in the
lower part of the specified frequency band.
– The ISM centre frequencies for dielectric heating and processing of industrial interest are
narrow bands about 6,78 MHz, 13,56 MHz, 27,12 MHz and 40,68 MHz.
– This document is not applicable to:
• appliances for household and similar use;
• commercial use;
• laboratory use;
• medical high frequency equipment.
For equipment working in designated ISM bands, it is a legal requirement that the frequency
remains within the ISM bands according to CISPR 11, but the resonant frequency of the circuit
varies with the change of dielectric parameters of the load. Therefore, the value of the mean
output power in the work cycle can be much lower than the value obtained under the test
conditions. This value depends upon the response of the tuning system.
NOTE 1 The following criteria are suitable for determination of the classification as industrial equipment:
– commercial equipment is typically designed and planned for series production of many identical units;
– industrial equipment is typically produced in small series or even as single units; the processed goods are
consumed or ready for final use at the end of the heating process.
NOTE 2 Heating a workload with dielectric parameters which change significantly in time and/or with temperature,
the value of the output power obtained with the actual charge can be different from that obtained with the test load
specified in this document.
This document relates to equipment normally operating under continuous rated
...