oSIST prEN IEC 80000-17:2026

• Status: Not Published
• Public Enquiry End Date: 30-Sep-2026
• ICS: 01.060 - Quantities and units
• ICS: 17.080 - Measurement of time, velocity, acceleration, angular velocity
• Technical Committee: I11 - Imaginarni 11
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 23-Jul-2026
• Due Date: 10-Dec-2026
• Completion Date: 29-Sep-2026
• Ref Project: prEN IEC 80000-17:2026 - Quantities and units - Part 17: Time dependency

• Referred By: oSIST prEN IEC 60335-2-11:2026 - Household and similar electrical appliances - Safety - Part 2-11: Particular requirements for tumble dryers
• Effective Date: 10-Feb-2026

oSIST prEN IEC 80000-17:2026 is the Slovenian standard identical to prEN IEC 80000-17:2026 from IEC. It belongs to the ISO/IEC 80000 series and specifies how to write and print symbols for time-dependent quantities, especially instantaneous, average, RMS, peak and component values. It is aimed at engineers, technical authors and standards users who need a consistent, language-independent notation for signals and other quantities that vary with time.

What does oSIST prEN IEC 80000-17:2026 specify?

oSIST prEN IEC 80000-17:2026 specifies the principles and symbols for quantities that depend on time. Its focus is notation, not measurement methods or product performance, so the value of the document is in how it standardizes symbols that appear in calculations, data sheets, drawings and technical standards.

The document is organized into:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and Definitions
• Clause 4 - Names and symbols for time-dependent quantities
• Clause 5 - Tables for time-dependent quantities
• Annex A - informative examples of time-dependent quantities
• Bibliography

Annex A illustrates how the symbol rules are applied to alternating, transient and random quantities.

Annex	What it covers
Annex A	Examples of time-dependent quantities, including alternating, transient and random cases

What are the key requirements of oSIST prEN IEC 80000-17:2026?

The main requirement of oSIST prEN IEC 80000-17:2026 is to use standardized symbol forms for time-dependent quantities so that the notation reads the same across languages and publications. Clause 4 and Clause 5 do most of the practical work: they tell you how to mark instantaneous values, averages, components and special functions.

Instantaneous values and average values

Clause 4.1 states that the symbol of a time-dependent quantity already implies time dependence and therefore an instantaneous value. When both upper-case and lower-case letters are used, lower-case represents an instantaneous value and upper-case an average value.

That matters in practice because a reader should not have to guess whether a symbol means a live value, an average, or another derived quantity. The clause also allows an explicit (t) for an instantaneous value, while warning against using a right-hand subscript t, which could be confused with differentiation.

Periodic and sinusoidal quantities

Clause 4.2 says that quantities varying periodically may be represented as a superposition of sinusoidal functions, described as a Fourier series. Clause 4.2.2 then gives standardized ways to write sinusoidal quantities and their complex representations.

In practice, this is the part to follow when you document AC quantities, phasors or harmonic content. The standard connects the instantaneous quantity, the RMS value, the peak value and the phase so that the notation stays consistent whether you write the signal in real form or in complex form.

RMS values and averaging

Clause 4.2.3 defines the root-mean-square (RMS) value as the positive square root of the mean of the squared quantity over a chosen time interval. For periodic quantities, the interval is normally tied to the period.

This matters when you specify electrical current, voltage or other time-varying values for calculation, reporting or comparison. The standard also notes common electrotechnical notation where I and U are used for RMS current and voltage.

Components and subscript order

Clause 4.3 sets out how to build subscripts for components of a combined quantity. The first subscript position identifies the type of component, the second the special component, and the third the associated value; commas can also be used to separate the parts.

The same clause allows a left-hand superscript to identify the order of a component in a series. That is useful when the subscript would otherwise become too long in harmonic or Fourier-series notation.

Standard symbol tables

Clause 5 provides the standardized symbol tables that users are expected to apply. These tables cover instantaneous values, absolute values, maxima and minima, peak-to-valley values, several kinds of averages, component symbols, values of Fourier-series components, running averages, and distribution or singularity functions.

In practice, the tables are the quick reference for choosing a symbol that means exactly what you intend. They reduce ambiguity when a signal has a constant part, an alternating part, a slowly changing part, or a special mathematical form such as a ramp, step or impulse.

What terms does oSIST prEN IEC 80000-17:2026 define?

oSIST prEN IEC 80000-17:2026 relies on the technical vocabulary of time-domain notation and related mathematics. These are the key terms used in the document:

• Time-dependent quantity - a quantity whose value changes with time; the standard treats its symbol as an instantaneous value unless another meaning is marked explicitly.
• Root-mean-square (RMS) value - the positive square root of the mean of the squared quantity over a specified time interval.
• Phasor - the complex-valued representation used for a sinusoidal quantity in the document’s examples.
• Fourier series - a way to represent a periodic quantity as a superposition of sinusoidal functions.
• Unit step function / Heaviside function - a singularity function listed in Table 5 for representing a step change in time.
• Dirac function - the unit impulse used in Table 5 to represent an impulse-like quantity.
• Running average - an average formed over a moving time interval, shown for arithmetic and RMS forms in Clause 5.
• Alternating component - a component of a combined quantity that varies with time and is shown in the tables and Annex A examples.

Who uses oSIST prEN IEC 80000-17:2026?

oSIST prEN IEC 80000-17:2026 is used by engineers, technical writers and standards developers who need consistent symbols for quantities that vary with time. It is especially relevant in electrical and electronic engineering, measurement, signal analysis, circuit theory and technical documentation.

It also matters for quality managers and buyers when they must read or compare specifications that use time-domain notation. If a drawing, report or standard uses RMS values, phasors, harmonics or component symbols, this document is the reference for the notation, not for the equipment itself.

What changed in oSIST prEN IEC 80000-17:2026 from the previous edition?

oSIST prEN IEC 80000-17:2026 is presented as a new part of the IEC 80000 series and as an excerpt from IEC 60027-1. The foreword states that this part, together with the future Part 16, will cancel and replace IEC 60027-1:1992+COR1:1993+AMD1:1997+AMD2:2005 ED6.0.

Which standards are used with oSIST prEN IEC 80000-17:2026?

The normative references named in Clause 2 are:

• ISO 80000-2:2019 - mathematics support for the symbols and notation used in the document.
• ISO 80000-6:2022 - electromagnetism terminology and symbols used in the examples and cross-references.
• IEC 60050-103 - mathematics - functions, used for the function names and concepts referenced in Clause 4.

The foreword and bibliography also point to related material such as ISO 80000-3:2019, IEC 60375:2018, IEC 60050-131, IEC 60050-112 and the SI Brochure.

What does the oSIST prEN IEC 80000-17:2026 document contain?

This document is mainly a notation guide. It contains symbol tables for time-dependent quantities, average quantities, components of combined quantities, some instantaneous or average values of a component, and distributions and singularity functions.

It also includes formulas and examples for sinusoidal quantities, RMS values, running averages and series notation. Annex A uses figures and equations to show alternating, transient and random combinations such as sums and products of constant, slowly changing and alternating parts.

The annex examples are useful when you need to write a signal description that is more complicated than a single pure sine wave. They show how the standard symbols are applied in real notation, which helps with drafting, review and interpretation of technical documents.

SLOVENSKI STANDARD
01-september-2026
Veličine in enote - 17. del: Časovna odvisnost
Quantities and units - Part 17: Time dependency
Grandeurs et unités - Partie 17: Dépendance temporelle
Ta slovenski standard je istoveten z: prEN IEC 80000-17:2026
ICS:
01.060 Veličine in enote Quantities and units
17.080 Merjenje časa, hitrosti, Measurement of time,
pospeška, kotne hitrosti velocity, acceleration,
angular velocity
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

25/853/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 80000-17 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-07-17 2026-10-09
SUPERSEDES DOCUMENTS:
25/844/RR
IEC TC 25 : QUANTITIES AND UNITS
SECRETARIAT: SECRETARY:
Italy Ms Daniela Zambelli
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 1,TC 2,TC 3,SC 3C,SC 3D,TC 4,TC 5,TC 7,TC 8,SC
8A,SC 8B,SC 8C,TC 9,TC 10,TC 11,TC 13,TC 14,TC
15,TC 17,SC 17A,SC 17C,TC 18,SC 18A,TC 20,TC 21,SC
21A,TC 22,SC 22E,SC 22F,SC 22G,SC 22H,TC 23,SC
23A,SC 23B,SC 23E,SC 23G,SC 23H,SC 23J,SC 23K,TC
26,TC 27,TC 29,TC 31,SC 31G,SC 31J,SC 31M,TC 32,SC
32A,SC 32B,SC 32C,TC 33,TC 34,SC 34A,SC 34B,SC
34C,SC 34D,TC 35,TC 36,SC 36A,TC 37,SC 37A,SC
37B,TC 38,TC 40,TC 42,TC 44,TC 45,SC 45A,SC 45B,TC
46,SC 46A,SC 46C,SC 46F,TC 47,SC 47A,SC 47D,SC
47E,SC 47F,TC 48,SC 48B,SC 48D,TC 49,TC 51,TC
55,TC 56,TC 57,TC 59,SC 59A,SC 59C,SC 59D,SC
59F,SC 59K,SC 59L,SC 59M,SC 59N,TC 61,SC 61B,SC
61C,SC 61D,SC 61H,SC 61J,TC 62,SC 62A,SC 62B,SC
62C,SC 62D,TC 64,TC 65,SC 65A,SC 65B,SC 65C,SC
65E,TC 66,TC 68,TC 69,TC 70,TC 72,TC 73,TC 76,TC
77,SC 77A,SC 77B,SC 77C,TC 78,TC 79,TC 80,TC 81,TC
82,TC 85,TC 86,SC 86A,SC 86B,SC 86C,TC 87,TC 88,TC
89,TC 90,TC 91,TC 94,TC 95,TC 96,TC 97,TC 99,TC
100,TA 1,TA 2,TA 5,TA 6,TA 15,TA 17,TA 18,TA 19,TA
20,TA 21,TC 101,TC 103,TC 104,TC 105,TC 106,TC
107,TC 108,TC 109,TC 110,TC 111,TC 112,TC 113,TC
114,TC 115,TC 116,TC 117,PC 118,TC 119,TC 120,TC
121,SC 121A,SC 121B,TC 122,TC 123,TC 124,TC
125,PC 126,PC
127,CISPR,CIS/A,CIS/B,CIS/D,CIS/F,CIS/H,CIS/I
ASPECTS CONCERNED:
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TITLE:
Quantities and units - Part 17: Time dependency

PROPOSED STABILITY DATE: 2030
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IEC CDV 80000-17 © IEC 2026
CONTENTS
Contact . 3
CONTENTS . 1
FOREWORD . 2
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and Definitions . 6
4 Names and symbols for time-dependent quantities . 6
4.1 General . 6
4.2 Quantities that vary with time periodically . 7
4.2.1 General . 7
4.2.2 Sinusoidal quantities. 7
4.2.3 Root-mean-square value ,RMS value, effective value . 7
4.3 Succession and position of information subscripts . 7
5 Tables for time-dependent quantities . 8
Annex A (informative) Examples of time-dependent quantities . 12
A.1 Examples of alternating quantities . 12
A.2 Examples of transient quantities . 17
A.3 Example of a random quantity . 19
Bibliography . 20

Figure A.1 – Sum of a constant component 𝑋0 and an alternating component 𝑥a . 12
Figure A.2 – Sum of two alternating components . 13
Figure A.3 – Product of two alternating components . 14
Figure A.4 – Sum of a constant component and two alternating components . 15
Figure A.5 – Sum of a constant component and three alternating components . 16
Figure A.6 – Product of a varying component and an alternating component . 17
Figure A.7 – Sum of two varying components and one alternating component. 18
Figure A.8 – Sum of a constant component and a random variable . 19

Table 1 – Symbols for time-dependent quantities . 8
Table 2 – Symbols for average quantities . 9
Table 3 – Symbols for components of a combined quantity . 9
Table 4 – Symbols for some instantaneous or average values of a component . 10
Table 5 – Distributions, singularity functions . 10

IEC CDV 80000-17 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Quantities and units -
Part 17: Time dependency
FOREWORD
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IEC CDV 80000-17 © IEC 2026
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 80000-17:202X has been prepared by TC 25/JWG 2: Revision and amendments of IEC-
related parts of ISO/IEC 80000 series of IEC technical committee TC25: Quantities and units.
It is an International Standard.
This 1st edition together with the future forthcoming Part 16 (Printing and writing rules) will
cancel and replace IEC 60027-1:1992+COR1:1993+AMD1:1997+AMD2:2005 ED6.0, Letter
symbols to be used in electrical technology - Part 1: General.
This new part is an excerpt from IEC 60027-1 according to IEC/TC 25 decision 2017/25-07
(Document 25/614/DL). This draft contains Clause 2, tables 9 and 10, and Annex C of
publication IEC 60027-1 Ed 6: 1995.
IEC 80000 consists of the following parts, under the general title Quantities and units:
Part 6: Electromagnetism
Part 13: Information science and technology
Part 15: Logarithmic and related quantities, and their units
Part 16: Printing and writing rules
Part 17: Time dependency
The following parts are published by ISO:
Part 1: General
Part 2: Mathematics
Part 3: Space and time
Part 4: Mechanics
Part 5: Thermodynamics
Part 7: Light
Part 8: Acoustics
Part 9: Physical chemistry and molecular physics
Part 10: Atomic and nuclear physics
Part 11: Characteristic numbers
Part 12: Condensed matter physics
The text of this International Standard is based on the following documents:
IEC CDV 80000-17 © IEC 2026
Draft Report on voting
25/XX/FDIS 25/XX/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
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specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC CDV 80000-17 © IEC 2026
INTRODUCTION
Time-dependent quantities can be periodic, transient or random and can be often represented
by a combination, e.g. sum, product, polynomial, etc., of components which are functions such
as trigonometric functions, exponentials, distributions, etc. They are denoted by specific
symbols which also can express specific characteristics like maximum, minimum, average by
various graphemes like subscripts, superscripts, diacritics, underscore, etc.
For time-dependent quantities, several different systems have been developed and used
depending on the number and the choice of base quantities on which the system is based.
However, in time dependency and electrical engineering, only the International Sys tem of
Quantities, ISQ, and the associated International System of Units, SI, are acknowledged and
are reflected in the standards of ISO and IEC. The SI has seven base units, among them meter,
symbol m, kilogram, symbol kg, second, symbol s, and ampere, symbol A.
The various possibilities for symbols for time-dependent quantities are presented in tables with
examples. No specific quantities are considered but place holders or abstract quantities.
All symbols and graphemes are language independent.
The items given in IEC 80000-17 are generally in conformity with the International
Electrotechnical Vocabulary (IEV).
...