Post-Installation Cable Testing: Subcontracting or In-House Testing

On a daily basis, power networks suffer from huge losses on account of cable system failure. In addition to undesired downtime caused by cables going out of order, substantial energy losses occur during electricity transmission due to the system malfunctioning. Yet, many of cable system failures can be prevented at the point of cable commissioning, provided proper post-installation cable testing is conducted.

Hiring a cable test contractor

One way to run post-installation cable testing is to hire an experienced professional contractor. When choosing one, it is advisable to take into consideration the following:

Reputation. Try to find out what other clients think of the contractor you are considering to hire. In the age of Internet, customer feedback can usually be found online, and it will be helpful to rule out contractors with a lot of dissatisfied clients or no reviews at all, which may be evidence of little experience.

Quote. Screening potential contractors, compare the quotes they offer for the job required.  Beware of those quoting a price considerably lower than that quoted by the others, as cable testing requires qualification, experience, and a range of quality cable test equipment – remember, all these things are not cheap. Also, the quote should include the details of the job involved; this way you will not only be able to see how reasonable the price is, but also assess whether the contractor knows what they are doing.

Knowledge of applicable standards. You need to make sure that your contractor is capable to run post-installation testing while following the standards that apply to your cable system.

Running cable testing in-house

If your decision is to run cable testing in-house, you need to be aware of the following:

Test standards and results. Whether you’ve hired a contractor or going to run cable testing in-house, it is important to agree on the test standards you’ll need to adhere to and, accordingly, how you are going to evaluate the test results. Therefore, before testing begins, you should have a list of measurements to obtain with respective reference values depending on the applicable standards. 

Staff training. A wide range of modern high voltage testing equipment allow for automatic effortless testing. However, this does not mean that you should neglect staff training. Quite the opposite, it is vital to invest in the education of the testing personnel, as this is essential for reliable test results and accurate interpretation.

The right cable testing equipment. Depending on your cable system, you may require a range of cable testing equipment. Prior to beginning the post-installation test, make sure you have instruments that will help to run cable proof testing (such as hipot testers) and, if cable failure is found, to prelocate the fault (usually with a TDR) and to conduct precise fault pinpointing (eg using a surge wave generator in conjunction with a surge wave locator ). Companies that do cable testing at large scales usually opt for cable test vans that integrate all the equipment required for cable testing.

Safe test area. High voltage cable testing should be conducted in accordance with best safety practice.

• The equipment used during cable testing should have safety interlocks and/or other safety features. 
• Even if the test set being used has an automatic discharge function, use the discharge stick to ensure that the object under test has been completely discharged.
• Make sure that only testing personnel are present at the testing site. You don’t need any bystanders there, whether public or company employees, as they are a potential hazard, first of all to themselves. 

Summing up, whatever you choose, to subcontract post-installation testing or two run it in-house, this job requires extensive preparation, so you need to identify the scope of testing, what standards to follow, which tests to run and measurements to make for comprehensive  assessment of the cable system being tested.

Alexei Tiatiushkin

Marketing manager

KharkovEnergoPribor Ltd.

marketing@keppowertesting.uk

http://www.kep.ua