💡 Voltage fluctuation and flicker testing — PN-EN 61000-3-3

Electronics and EMC PN-EN 61000-3-3

Overview

SCOPE FROM THE PKN CATALOGUE CARD, QUOTED VERBATIM: "Niniejsza część IEC 61000 dotyczy ograniczania wahań napięcia i migotania światła występujących w publicznych sieciach zasilających niskiego napięcia. Określono w niej poziomy dopuszczalne zmian napięcia, które mogą być powodowane przez urządzenia badane w określonych warunkach, i podano wskazówki dotyczące metod ich oceny. Niniejsza część IEC 61000 dotyczy urządzeń elektrycznych i elektronicznych o zasilającym prądzie fazowym do 16 A włącznie, przeznaczonych do bezwarunkowego przyłączania do publicznych sieci rozdzielczych niskiego napięcia o napięciu fazowym od 220 V do 250 V i częstotliwości 50 Hz." [This part of IEC 61000 concerns the limitation of voltage fluctuations and flicker in public low-voltage supply networks. It specifies limits of voltage changes that may be produced by equipment tested under specified conditions and gives guidance on methods of their assessment. This part of IEC 61000 applies to electrical and electronic equipment with an input current up to and including 16 A per phase, intended to be connected unconditionally to public low-voltage distribution networks with a phase voltage of 220 V to 250 V and a frequency of 50 Hz.]

WHAT TO DO WHEN THE EQUIPMENT DOES NOT MEET THE REQUIREMENTS — THE ANSWER IS IN THE SCOPE ITSELF. The card says: "Urządzenia, które nie spełniają wymagań dla poziomów dopuszczalnych określonych w tej części IEC 61000 podczas badania z impedancją odniesienia Zref zgodną z 6.4 i których z tego powodu nie można uznać za zgodne z niniejszą częścią, można ponownie badać lub oceniać, aby wykazać zgodność z IEC 61000-3-11. Część 3-11 dotyczy urządzeń o znamionowym fazowym prądzie zasilającym ≤ 75 A i podlegających przyłączeniu warunkowemu." [Equipment that does not meet the limits specified in this part of IEC 61000 when tested with the reference impedance Zref according to 6.4, and that therefore cannot be considered compliant with this part, may be retested or evaluated to show conformity with IEC 61000-3-11. Part 3-11 applies to equipment with a rated input current ≤ 75 A per phase and subject to conditional connection.] Failing the test therefore does not end the product's path — it only changes the basis of assessment and the conditions of connection.

THE REFERENCE IMPEDANCE IS NOT IN THIS STANDARD — AND THAT IS THE MOST IMPORTANT THING FOR THE READER. The test is carried out with a reference impedance designated Zref, but its values come from IEC 60725, not from this standard. The catalogue sheet of a manufacturer of measuring equipment gives them as: line 0.24 Ω + j0.15 Ω and neutral conductor 0.16 Ω + j0.10 Ω, with an explicit statement that this is the impedance "according IEC 60725". A reader who takes up Part 3-3 alone will not find these numbers there; the scope refers only to clause 6.4 of its own text, and that clause to a separate document.

TESTS ACCORDING TO THIS STANDARD ARE TYPE TESTS. The scope says so directly: "Badania zgodne z niniejszą częścią są badaniami typu. Szczegółowe warunki badań określono w Załączniku A, a obwód pomiarowy przedstawiono na Rysunku 1." [Tests according to this part are type tests. Particular test conditions are given in Annex A, and the measuring circuit is shown in Figure 1.] The result therefore concerns a specimen representative of production, not an individual unit.

A WARNING FROM THE SCOPE ITSELF ABOUT THE LIMITS OF APPLYING THE RESULT. The card quotes a note: "Poziomy dopuszczalne podane w niniejszej normie dotyczą zmian napięcia występujących u odbiorców podłączonych do interfejsu pomiędzy publiczną siecią zasilającą niskiego napięcia a instalacją urządzeń użytkowników. W konsekwencji, gdy rzeczywista impedancja zasilania na zaciskach zasilania urządzeń podłączonych w granicach instalacji użytkowników przekracza impedancję badania, możliwe jest wystąpienie zakłóceń w zasilaniu, przekraczających poziomy dopuszczalne." [The limits given in this standard relate to the voltage changes experienced by consumers connected at the interface between the public low-voltage supply network and the users' equipment installation. Consequently, when the actual supply impedance at the supply terminals of equipment connected within the users' installation exceeds the test impedance, supply disturbances exceeding the limits may occur.] Passing the test therefore does not guarantee the absence of flicker in a specific installation — it guarantees conformity under reference conditions.

QUANTITIES ASSESSED — FROM A SECONDARY SOURCE, NOT FROM THE STANDARD. The description of the service of a testing laboratory gives five quantities with limit values for this standard: the short-term flicker indicator Pst not greater than 1.0 with an observation window of 10 minutes; the long-term flicker indicator Plt not greater than 0.65 with a window of two hours; the relative voltage change as a function of time d(t) not greater than 3.3 %; the steady-state relative voltage change dc not greater than 3.3 %; the maximum relative voltage change dmax not greater than 4 %. We have not established the duration for which d(t) may exceed the given value.

STATUS OF THE DOCUMENT ON 22-09-2026. The card of PN-EN 61000-3-3:2013-10 has neither the "Wycofana" [Withdrawn] header nor a "Data wycofania" [withdrawal date] row — the edition is current. The standard implements EN 61000-3-3:2013 [IDT] and IEC 61000-3-3:2013 [IDT], replaces PN-EN 61000-3-3:2011 (Polish-language version), and the collection contains amendments A1:2019-10 and A2:2022-04 to it in English-language versions. The designation does NOT have the IEC element — checked separately on the card, because TWO other standards described in this database received such an element in their newer edition (PN-EN IEC 60068-2-78:2026-09 and PN-EN IEC 55011:2026-06).

WHAT WE DO NOT GIVE AND HOW WE KNOW IT. We did not have the text of the standard — PKN makes it available for a fee (44 pages, ICS 33.100.20, Technical Body KT 104). The Zref values come from the catalogue sheet of a manufacturer of the equipment, and the limit values of the indicators — from the description of a laboratory's service; both are a supplier's declaration, not a quotation from the standard. WE DO NOT GIVE: the content of Annex A with the test conditions, the circuit from Figure 1, the method of determining Pst and Plt, the operating conditions of the equipment during the test or the rules for equipment with intermittent operation. All of this is the content of the standard.

Method principle

The equipment under test is connected to the power source through the reference impedance, and the voltage waveform at the point of connection is recorded while the equipment operates under the conditions specified in the standard. From the recorded waveform, the voltage changes and flicker indicators are determined: the short-term Pst over a ten-minute window and the long-term Plt over a two-hour window, as well as the relative voltage changes d(t), dc and dmax. The results are compared with the limit values. The reference impedance is a condition of the measurement here: the same operation of the equipment with a different impedance gives different voltage fluctuations, which is why the result makes sense only together with it.

Applications

• Type testing of household appliances connected unconditionally to the low-voltage network
• Testing of tools and equipment with intermittent operation causing load fluctuations
• Assessment of product conformity with the requirements of Directive 2014/30/EU
• Preliminary qualification of a product before assessment according to PN-EN 61000-3-11 for conditional connection (current edition PN-EN IEC 61000-3-11:2020-01 — English-language version only; Polish only for the withdrawn 2004 edition)
• Testing of lighting equipment, in which flicker is a directly visible phenomenon

Key parameters

Standard

Standard number

PN-EN 61000-3-3:2013-10 (wersja angielska; wprowadza EN 61000-3-3:2013 [IDT] i IEC 61000-3-3:2013 [IDT])

Title (PL)

Kompatybilność elektromagnetyczna (EMC) — Część 3-3: Poziomy dopuszczalne — Ograniczanie zmian napięcia, wahań napięcia i migotania światła w publicznych sieciach zasilających niskiego napięcia, powodowanych przez odbiorniki o fazowym prądzie znamionowym ≤ 16 A przyłączone bezwarunkowo

Title (EN)

Electromagnetic compatibility (EMC) — Part 3-3: Limits — Limitation of voltage changes, voltage fluctuations and flicker in public low-voltage supply systems, for equipment with rated current ≤ 16 A per phase and not subject to conditional connection

Step-by-step procedure

1. Checking whether the product falls within the scope of the standard

   Phase current up to and including 16 A and unconditional connection to the public low-voltage network with a phase voltage of 220 V to 250 V and a frequency of 50 Hz. A product with a higher current or connected conditionally is assessed according to IEC 61000-3-11.

2. Setting up the measuring circuit with the reference impedance

   The equipment is connected through the reference impedance Zref, whose values come from IEC 60725, not from this standard. WE DO NOT GIVE THE CIRCUIT FROM FIGURE 1 AND THE CONDITIONS FROM ANNEX A.

3. Reproducing the operating conditions of the product

   The equipment operates under the conditions specified in the standard, reproducing typical use; for products with intermittent operation the switching cycle is essential. WE DO NOT GIVE THE DETAILS.

4. Recording the voltage waveform

   The voltage at the point of connection is recorded for the time needed to determine the indicators: ten minutes for Pst and two hours for Plt.

5. Determining the indicators and voltage changes

   Pst, Plt and d(t), dc and dmax are determined from the waveform. WE DO NOT GIVE THE METHOD OF CALCULATING THE INDICATORS — it is in the text of the standard.

6. Comparison with the limit values

   Each quantity is compared with its limit value, always given together with the condition: Pst with the 10-minute window, Plt with the two-hour window.

7. Procedure in the event of failure

   A product that does not meet the requirements when tested with the reference impedance may be retested or assessed according to IEC 61000-3-11 as subject to conditional connection.

8. Recording the result together with the reference conditions

   In the report, the result is given together with the reference impedance and the observation windows. A Pst value without a window and without an impedance does not say under what conditions it was obtained.

Required equipment and apparatus

Health and safety (OHS)

• The test is carried out at mains voltage — the measuring circuit and the reference impedance remain live throughout the recording
• The reference impedance heats up at high load currents — maintain the clearances and ventilation provided for by the manufacturer
• Products with intermittent operation may start automatically during recording — mark the test station and do not leave it unattended
• When testing luminaires, high-amplitude flicker can be a nuisance to the operators — limit the time of direct observation

Frequently asked questions