🌡️ Test N: Change of temperature (Na, Nb, Nc) — PN-EN IEC 60068-2-14

Electronics and EMC PN-EN 60068-2-14

Overview

SCOPE FROM THE PKN CARD: "W niniejszym dokumencie opisano próby z określonymi zmianami temperatury otoczenia w celu analizy ich wpływu na próbkę." [This document describes tests with specified changes of ambient temperature in order to analyse their effect on the specimen.] The card of the 2009 edition described this more broadly: the endurance of components, equipment and other products to rapid changes of ambient temperature, the test parameters, the choice of the type of test (Na, Nb, Nc), the chamber and the severities.

THREE TESTS — WHAT EACH IS FOR (5.4 of the edition IEC 60068-2-14:2023): • Na — rapid change of temperature in air or an inert gas; for assessing electrical properties after a specified number of rapid changes, and the resistance of mechanical elements, materials and their joints and of the design of components to artificial stresses; • Nb — change of temperature at a specified rate; for assessing electrical and mechanical performance as a result of the change of temperature; • Nc — rapid change by the two-liquid-bath method; application as for Na. The standard stipulates that tests N are not intended for assessing differences in material constants or the electrical performance of the product AT the conditioning temperatures TA and TB THEMSELVES (5.4).

WHAT THE STANDARD SETTLES ITSELF (clause 5, extract of the 2023 edition): • CYCLE: the transition from laboratory temperature to the first conditioning temperature, then to the second and back to laboratory temperature is ONE cycle (5.2); • STABILISATION: it occurs when the temperature difference between the specimen and the medium (ΔTs) is within 5 K or within the value from the specification; the exposure time t1 at each temperature is to be LONGER than the stabilisation time ts (5.5); • TRANSFER: the transfer time t2 between two chambers is to be within 3 minutes; when a large specimen does not permit this, t2 may be extended on condition that t2 ≤ 0.05·ts — this applies only to the two-chamber method, in the single-chamber method t2 does not occur (5.6); • ACCELERATION: the test is accelerated because there are more changes than under real conditions; temperatures outside the normal storage or operating range of the product may be specified only in exceptional cases (5.3); • BATHS (Nc): the two-bath method with water is limited to sealed products or products insensitive to water; Nc is NOT a substitute for the sealing test Q (IEC 60068-2-17) (5.7). The standard recommends applying tests N in a sequence, because some damage becomes apparent only in subsequent tests — as examples it gives Q (sealing), Fc (sinusoidal vibration), Db (damp heat, cyclic) or Cy (5.7).

EDITIONS (state of the PKN cards and the IEC website on 25.09.2026). PN-EN IEC 60068-2-14:2024-04 — English-language version, publication 23-04-2024, 44 pages, KT 65 Environmental Testing of Electrical Products; it implements EN IEC 60068-2-14:2023 and IEC 60068-2-14:2023 [IDT]; it replaces PN-EN 60068-2-14:2009 and its corrigendum Ap1:2016-07. The card has no "Withdrawn" header. PN-EN 60068-2-14:2009 (English-language version, publication 28-08-2009) — WITHDRAWN 23-04-2024; it had itself replaced PN-EN 60068-2-14:2002 and PN-EN 60068-2-33:2002. At the publisher: IEC 60068-2-14:2023, edition 7.0 of 2023-07-27, stability date 2027. According to the foreword, the seventh edition is a technical revision: the figures, specimen temperatures, severities and tolerances and the requirements for reports of tests Na and Nb were updated.

HOW ACCREDITATION SCOPES CITE THE STANDARD. Measurement of 25.09.2026 on the database of PL accreditation scopes (1310 laboratories with entries): 26 entries at 20 laboratories. Forms of notation: "PN-EN IEC 60068-2-14:2024-04" (7), "PN-EN 60068-2-14:2009" (6, a withdrawn edition), "PN-EN 60068-2-14:2024-04" WITHOUT the IEC element (6 — a form that does not exist in the catalogue), "PN-EN 60068-2-14" without a year (3), "IEC 60068-2-14:2023" (2) and single IEC and EN notations with the letters of the tests ("Test Na, Test Nb"). EXCLUSION OF TEST Nc: one entry cites both editions "z wył. pkt. 9" [z wył. pkt. = excluding clause] — in the 2023 edition clause 9 is precisely test Nc (two liquid baths). Declared capabilities of the test stations: temperatures from -70 °C to +180 °C, "Transfer < 20 sekund" [sekund = seconds], "Zbocze ≤ 15 °C na minutę" [zbocze = ramp, na minutę = per minute], "Tempo zmian do 1 K/min" [tempo zmian do = rate of change up to], "Próba: Na, Nb (do 4 K/min), Nc" [próba = test, do = up to]. Next to the standard stand specifications of vehicle manufacturers, ISO 16750-4, NO-06-A107 and MIL-STD 810F.

THE KEY OF THE "LABORATORIES" TAB: "PN-EN 60068-2-14" — 12 laboratories and 17 entries, without any foreign entries. It was chosen instead of the designation in force ("PN-EN IEC 60068-2-14" — 9 laboratories, 10 entries) because the notation without the IEC element carries both the 2009 edition and the non-existent form of the 2024 edition. The tab will not show 8 laboratories (AB 022, AB 1132, AB 124, AB 1776, AB 1899, AB 1974, AB 261, AB 516), which write only the form with the IEC element or the IEC or EN designation alone.

WHAT WE DO NOT GIVE. We had an extract of IEC 60068-2-14:2023 made available by the publisher: the foreword, the table of contents and the text up to 7.2.1 (the chamber in test Na). WE DO NOT HAVE 7.2.3 and 8.2.3 with the severities, 8.2.4 with the tolerances, the course of the cycles (7.2.5, 8.3, 9.3), recovery or the normative Annex C with the table of tolerances for test Nb. We do not give any temperature, rate of change or number of cycles.

Method principle

The product is exposed alternately to a low and a high temperature with a specified transition between them. In test Na it is transferred rapidly between two chambers (or the temperature is changed in a single rapid-change chamber), in Nb the temperature is changed at a specified rate, and in Nc it is transferred between two liquid baths. The exposure time at each temperature is to be longer than the stabilisation time of the specimen (temperature difference between the specimen and the medium within 5 K). Damage is assessed by the initial and final measurements indicated in the product specification.

Applications

• Automotive electronics — next to ISO 16750-4 and the specifications of vehicle manufacturers
• Electrotechnical products, switches, wiring harnesses, cells and batteries
• (Road) warning signalling devices and military equipment
• Assessment of joints of materials with different thermal expansion — solders, seals, coatings
• An element of a sequence of climatic tests: sealing, vibration, damp heat

Key parameters

Standard

Standard number

PN-EN IEC 60068-2-14:2024-04 (wersja angielska; wprowadza EN IEC 60068-2-14:2023 [IDT], IEC 60068-2-14:2023 [IDT])

Title (PL)

Badania środowiskowe — Część 2-14: Próby — Próba N: Zmiany temperatury

Title (EN)

Environmental testing — Part 2-14: Tests — Test N: Change of temperature

Step-by-step procedure

1. Choice of test

   Na or Nc for assessment after a series of rapid changes, Nb for assessing performance during changes at a specified rate; Nc only for sealed products or products insensitive to the liquid.

2. Initial measurements

   Visual inspection and electrical and mechanical checking in accordance with the product specification (6.2).

3. Parameters from the other document

   The temperatures TA and TB, the exposure time t1, the transfer time t2 or the rate of change dTR and the number of cycles are taken from the product specification — WE DO NOT GIVE the recommended values.

4. Cycles

   Each cycle: from laboratory temperature to the first conditioning temperature, to the second and back; t1 longer than the stabilisation time ts; in the two-chamber method t2 with reference to 3 min (or t2 ≤ 0.05·ts).

5. Recovery and final measurements

   In accordance with the specification; WE DO NOT GIVE the details of recovery.

6. Report

   State the test (Na, Nb, Nc), the edition of the standard, the method (single- or two-chamber) and all cycle parameters — the 2023 edition changed the requirements for reports of tests Na and Nb.

Required equipment and apparatus

Health and safety (OHS)

• Extremely cold and hot surfaces of chambers and specimens — thermal gloves
• Automatic transfer of the basket between chambers — access interlock during operation
• Test Nc with liquids other than water — safety data sheet of the liquid, ventilation

Frequently asked questions