SIST EN IEC 60691:2024/A2:2026

SIST EN IEC 60691:2024/A2:2026 is Amendment 2 to IEC 60691 on thermal-links, published by SIST. It updates the requirements and application guide for thermal-links, with detailed test conditions for holding temperature in Annex I. It is written for manufacturers, test laboratories, certification teams and others who evaluate thermal protective devices.

What does SIST EN IEC 60691:2024/A2:2026 specify?

SIST EN IEC 60691:2024/A2:2026 specifies amendment text for the thermal-links standard, focused on Annex I and the holding temperature test. The amendment also points users to Annex H for thermal-link packaged assemblies.

In practical terms, this amendment tells you how to run and assess the holding-temperature test so that results are repeatable and comparable. That matters for type testing, conformity assessment and production control.

What are the key requirements of SIST EN IEC 60691:2024/A2:2026?

Annex I applicability and test setup

Annex I is informative, but it applies when the manufacturer declares it, and it is required in Germany. That means a supplier needs to know whether Annex I is part of the declared test basis before claiming compliance.

Annex I.11.2 requires the static-air oven temperature to be measured as close as possible to the center of the space occupied by the test fixture assembly, at about 50 mm from it. The temperature is to be measured with fine wire thermocouples of 0,081 mm² or other equivalent means with minimum effect on the test temperature.

Annex I.11.2 also limits temperature spread in the test area. The oven must stay within ± 1 K at nominal temperatures of 200 °C or lower, or within ± 0,5 % of the nominal temperature above 200 °C. In practice, this is a control requirement for the test lab, because uneven heating can change the result.

Fixture, specimens and stabilization

Annex I.11.2.1 says the wire size, wire type or termination method used to connect the thermal-link to the electrical load shall not significantly affect the thermal-link temperature. The intent is to avoid a heatsink effect, so the fixture does not distort the test.

Annex I.11.2.2 treats the oven as stabilized when two readings taken 5 minutes apart are within 1 K of each other. This gives the lab a clear rule for when the oven is ready for testing.

Annex I.11.2.3 places the three group K specimens on a test fixture assembly, mounted so they are not in direct contact with the internal walls of the oven and are electrically isolated from them. The note allows the three specimens to be tested individually, which can simplify handling and setup.

Test duration and pass/fail check

Annex I.11.2.4 requires the three specimens in series to be placed in the stabilized static-air oven at the manufacturer-specified Th temperature, then energized with the resistive rated current for 24 hours or for the longer time declared by the manufacturer. This defines the exposure that the thermal-link must survive.

Annex I.11.2.5 says compliance is checked by continuity after the test, and the thermal-link shall not change its state of conductivity. In practice, the part must still behave as intended after the holding-temperature exposure.

Annex I.11.2.6 directs users to Annex H for thermal-link packaged assemblies. That means packaged products follow additional requirements beyond the Annex I test sequence.

What terms does SIST EN IEC 60691:2024/A2:2026 define?

• Thermal-link - A thermal protective device that changes its conductive state when a specified temperature condition is reached.
• Holding temperature (Th) - The temperature declared by the manufacturer for the holding-temperature test.
• Static-air oven - The oven used for the test, where air movement is limited so the thermal environment can be controlled.
• Group K - The set of three specimens used in the Annex I test arrangement.
• Resistive rated current - The current used to energize the thermal-links during the test.
• State of conductivity - Whether the thermal-link still conducts or has changed state after testing.

Who uses SIST EN IEC 60691:2024/A2:2026?

SIST EN IEC 60691:2024/A2:2026 is used by thermal-link manufacturers, test laboratories, conformity assessment bodies and quality teams. It is relevant when defining test methods, setting up ovens and fixtures, checking thermal behavior and recording pass/fail results.

It also matters to buyers and engineering teams that specify thermal protection devices in electrical equipment. They use it to compare products on the same test basis and to check whether a supplier’s declared test conditions match the declared use.

What changed in SIST EN IEC 60691:2024/A2:2026 from the previous edition?

SIST EN IEC 60691:2024/A2:2026 is Amendment 2 to IEC 60691:2023. The amendment updates Annex I for the holding-temperature test, adds the rule that Annex I is applicable when declared by the manufacturer and required in Germany, and tightens the instructions for temperature measurement, stabilization, specimen mounting, exposure time and continuity checking.

Which standards are used with SIST EN IEC 60691:2024/A2:2026?

The base document named here is IEC 60691:2023, which this amendment updates. The text also refers users to Annex H of the same standard for thermal-link packaged assemblies.

What does the SIST EN IEC 60691:2024/A2:2026 document contain?

The document contains amendment text for Annex I, including revised wording for the holding-temperature test. It gives the test setup for the static-air oven, the measurement location, the allowed sensing method, the temperature uniformity limits and the stabilization criterion.

It also covers specimen arrangement, including the three group K specimens, their isolation from the oven walls and the option to test them individually. The final part of the test sequence is the current exposure and the continuity check used to confirm that the thermal-link has not changed state.

For packaged assemblies, the document points to Annex H rather than repeating those requirements here.