SIST EN 60168:1997/A1:1998

SIST EN 60168:1997/A1:1998 is the Slovenian adoption of the European Norm (EN) amendment aligned with International Electrotechnical Commission (IEC) 60168:1994/A1:1997. It covers tests on indoor and outdoor post insulators of ceramic material or glass for systems with nominal voltages greater than 1 kV. In practice, it tells manufacturers, test laboratories, and buyers how these post insulators are selected, mounted, and checked for electrical and mechanical performance.

What does SIST EN 60168:1997/A1:1998 specify?

SIST EN 60168:1997/A1:1998 amends the test standard for post insulators used on high-voltage systems. The update touches the values used to characterize a post insulator, the selection of insulators for type tests, the rules for extending test results to equivalent designs, the standard mounting arrangements for tests, and the routine tests for ceramic and glass products.

The amendment is organized around selected clauses in the base document and three annexes.

What are the key requirements of SIST EN 60168:1998/A1:1998?

• Switching-impulse withstand voltage is to be specified only for post insulators used on alternating-current (a.c.) systems with highest voltage for equipment above 245 kV. In practice, this limits when that value belongs in the specification, so buyers do not ask for a parameter that does not apply to the intended service.

• Type tests are carried out on insulator(s) that have passed the routine and sample tests, except the sample mechanical test. This matters because the type-test specimen must already represent production quality, not a part that would fail basic checks.

• Type-test selection normally uses one post insulator per test, and insulators that have undergone type tests affecting mechanical or electrical characteristics are not to be used in service. That protects installed equipment from being fitted with test articles whose properties may have been altered.

• Electrical type-test results may be extended to post insulators of an electrically equivalent design when the materials and listed dimensional features match the reference design. This allows one qualified design to cover a family of similar designs, which reduces repeat testing when the electrical behaviour is represented adequately.

• Mechanical failing load type-test results may be extended to post insulators of a mechanically equivalent design when they are made in the same factory, from the same materials and process, and meet the listed geometric conditions. In practice, this supports family approval while keeping the manufacturing route and load path comparable.

• Standard mounting arrangements are given for tests with and without switching-impulse requirements. The post insulator is mounted vertically on an earthed metal support with a specified conductor arrangement, so the test setup is repeatable and the results can be compared between laboratories.

• Routine tests are defined by material and height in Table 5. Ceramic post insulators include routine visual inspection, a mechanical test, and a routine electrical test; glass post insulators include routine thermal shock testing, visual inspection, and a mechanical test. The height threshold separates bending and tensile test arrangements, so the factory test matches the product geometry.

• Unassembled post insulator units may, by agreement between purchaser and manufacturer, be routine-tested before assembly. The bending load is then applied in several directions, and the test does not verify the metal fittings or the assembly. This option is useful when the insulating part is checked separately from final assembly.

The amendment also tightens the rules for ceramic post insulators: on the core of a cylindrical post insulator unit, chips and cracks are not permitted, while small unglazed areas and small glaze inclusions are allowed.

What terms does SIST EN 60168:1998/A1:1998 define?

• Post insulator - An insulator used indoors or outdoors on systems with nominal voltages greater than 1 kV.
• Type tests - Tests performed on specimens that have already passed the routine and sample tests, except the sample mechanical test.
• Routine tests - The tests applied to all insulators in production, as listed in Table 5.
• Sample tests - A testing stage referenced for selecting type-test specimens and for the mechanical test exception.
• Electrically equivalent design - A design whose materials and key dimensions allow electrical type-test results to be extended to other post insulators.
• Mechanically equivalent design - A design from the same factory, materials, and process, with matching features that allow mechanical failing load results to be extended.
• Highest voltage for equipment - The voltage level used to decide when switching-impulse withstand voltage and certain mounting arrangements apply.

Who uses SIST EN 60168:1998/A1:1998?

SIST EN 60168:1997/A1:1998 is used by manufacturers of ceramic and glass post insulators, test laboratories, utility engineers, substation designers, and purchasing teams. They use it when specifying products, planning qualification tests, checking production lots, and deciding whether one tested design can represent a family of similar insulators.

Quality managers and buyers use it to compare supplier test evidence against a common test framework. Engineers use it to choose the correct mounting arrangement and to understand which tests apply to a given voltage level, material, or insulator height.

What changed in SIST EN 60168:1998/A1:1998 from the previous edition?

SIST EN 60168:1997/A1:1998 amends EN 60168:1994/A1:1997 and IEC 60168:1994/A1:1997. The amendment changes:

• the note on switching-impulse withstand voltage in clause 2.2
• the description of type-test specimens in clause 3.1.1
• the selection rule for type tests in clause 3.3.1
• the extension rules for electrical type tests in clause 3.3.3
• the extension rules for mechanical failing load type tests in clause 3.3.4
• the standard mounting arrangements in clause 4.4.1 and clause 4.4.2
• the note on top metal fittings in clause 5.2.4.4
• the surface-defect rule for ceramic insulating parts in clause 5.8.1
• the option for testing unassembled units in clause 5.9.1.2
• Table 3 and Table 5
• figures in Annex A and Annex B
• the bibliography in Annex C

What does the SIST EN 60168:1998/A1:1998 document contain?

The document contains amended text for testing conditions, specimen selection, design equivalence, mounting arrangements, and routine inspection. It also includes Table 3 for type-test applicability, Table 5 for routine tests by material and design category, and the annex methods for dimensional tolerances and unassembled-unit testing.

Annex A gives figure-based methods for checking parallelism, eccentricity, angular deviation, camber, and shed angle. Annex B gives the routine-test method for unassembled insulator units, including the bending-moment relationship used for the test setup. Annex C updates the bibliography, including IEC 61264 and several renumbered references.