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PORCELAIN INSULATOR|BS EN 60168:1995 IEC 60168:1994(8)

PORCELAIN INSULATOR|BS EN 60168:1995 IEC 60168:1994(8)


5.9.1.1.1 Routine mechanical test on complete post
The normal test load shall be equal to 50 % of the specified mechanical failing load. It shall be applied in
four mutually perpendicular directions, each for a minimum time of 3 s.

Alternatively, by agreement between the purchaser and the manufacturer at the time of ordering, a
bending test with a load up to 70 % of the specified mechanical failing load may be applied in more than
one direction, each for a minimum time of 3 s.
NOTE This agreement between the purchaser and the manufacturer should take into account the possible effects of higher test loads
on the integrity of the joints between the porcelain or glass parts and the metal fittings.

5.9.1.1.2 Routine mechanical test on the top metal fitting
The test procedure used depends on the strength requirements specified by the purchaser.
— When the purchaser has specified a requirement for linearity in strength progression from 0,5 Poh
or 0,2 Poh (according to the designation of the post insulator) to Poh the routine test shall be conducted
on the complete insulator, using an extension piece. The length of the extension piece and the applied
load shall be adjusted to achieve the required bending moment, according to 5.9.1.1.1 at the bottom of
the post insulator.
— When the purchaser has not specified a requirement for linearity in strength progression, it may not
be possible to carry out the routine mechanical test on the complete post insulator, using an extension
piece. In this case, and also when the bending strength at the top metal fitting is of special importance,
an additional test, if required by the purchaser, shall be made on the top unit. The details of the test,
either using an extension piece, or testing with the unit inverted, shall be agreed at the time of ordering.

5.9.1.1.3 Routine mechanical test determined by service applications
When required by service applications, the purchaser and the manufacturer may agree to a different form
of routine test, e.g. a torsion test, a tensile test, or a compressive test. The details shall be agreed at the
time of placing the order. www.asiapower.net

5.9.1.2 Unassembled post insulators
As an alternative to a routine bending test on an assembled post insulator, the routine mechanical test
may, by agreement between the purchaser and the manufacturer, be made on the insulating part of a
cylindrical post insulator or post insulator unit, prior to assembly. In this case, bending loads shall be
applied in several directions. They shall be of sufficient magnitude to ensure that the bending stress
achieved at each position along the free or unsupported length of the insulating part is equivalent to at
least 70 % and does not exceed 100 % of the stress at that position corresponding to the specified
mechanical failing load.
NOTE 1 Suitable methods for routine mechanical testing of unfitted insulator units are indicated in Annex B.
NOTE 2 It should be noted that this test does not verify the metal fittings or the assembly of the post insulator.

5.9.2 Cylindrical post insulators in design categories 1), 2), 3), 4) and 6) with a nominal
height h k 770 mm
Unless otherwise agreed between the purchaser and the manufacturer, a routine mechanical test need not
be carried out on cylindrical post insulators with a nominal height h k 770 mm. If a routine mechanical
test is required, then it normally shall be a tensile test or a bending test, and the details shall be agreed at
the time of ordering.

5.9.3 Pedestal post insulators, design category 5)
The routine mechanical test normally shall be a tensile test. The test load shall be equal to 30 % of the
specified mechanical failing load applied in tension for a minimum time of 3 s.
The routine mechanical test on post insulators in design categories 4) and 5) shall be carried out before the
routine electrical test.

5.9.4 Acceptance criteria
After the routine mechanical test, each post insulator shall be carefully examined. Any damaged insulator,
including those in which the metal fittings have broken, or have started to become detached, shall be
rejected. www.asiapower.net
 
Section 6. Tests applicable to post insulators
...to be continued

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