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Testing Cable Terminations Under Polluted Conditions

June 24, 2017 • ARTICLE ARCHIVE, Cable Accessories, Testing
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With currently available technology, the test bays can even be observed by remote access to the measuring system and test engineers informed about events by mobile phone or e-mail. This ensures that there will be only minimal delay should there be any unexpected interruption to the test.

Salt Fog & Solid Layer Tests on HV Porcelain Terminations

While for MV terminations pollution behaviour is tested using the procedure discussed above, no such methodology is requested by the standards in the case of HV terminations. For those terminations equipped with a porcelain housing, IEC 60507 (AC tests) or IEC/TS 61245 (DC tests) can be applied. But since cable terminations are not specifically mentioned in these standards, it seems left open how the test set-up should be prepared.

In any case, the standard can be understood to test the termination under service conditions – exactly as proposed for components such as wall bushings. Here, a short cable loop must be prepared and the termination to be tested is installed at one end. The other end must also be sealed, either with another termination of at least the same pollution withstand or using a GIS plug and compartment. In the latter case, the test assembly is easier to handle and re-locate within the laboratory.

Cable terminations in salt fog chamber with different kinds of cable end sealing.  cable termination Testing Cable Terminations Under Polluted Conditions Screen Shot 2016 10 21 at 11

Cable terminations in salt fog chamber with different kinds of cable end sealing.
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IEC 60507 (for AC tests) and IEC/TS 61245 (for DC tests) describe essentially the same test procedure with the difference being mainly in test voltage. Before the test is started, a decision is made whether the solid layer method or salt fog method is to be applied. While results in both cases are generally recognized as being equivalent, there is a tendency toward salt fog testing to simulate service conditions in coastal areas. The solid layer method, by contrast, is usually preferred to simulate stresses in regions where solid pollution layers of dust, sand etc. can build up on the termination. Table 2 shows essential details of the test requirements for the salt fog method and Table 3 for the solid layer method.

Test Conditions for Salt Fog Tests cable termination Testing Cable Terminations Under Polluted Conditions Screen Shot 2016 10 21 at 11

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Cable terminations in salt fog chamber with different kinds of cable end sealing.  cable termination Testing Cable Terminations Under Polluted Conditions Screen Shot 2016 10 21 at 11

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Pollution Tests on HV Composite Terminations

Since non-ceramic insulators are now increasingly being used on power grids worldwide, there is an important need to test their behaviour under polluted conditions. At the moment, however, the only IEC test for hollow composite insulators used in cable terminations is the tracking and erosion test, according to IEC 62217/IEC 61462.

cable termination Testing Cable Terminations Under Polluted Conditions Screen Shot 2017 06 23 at 16

Pollution performance of porcelain-housed terminations can be tested using either salt fog or solid layer methods.
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