Standard practice

Craig Diack-Evans, senior international business development manager at Intertek says: “Utilities want reliable equipment and they want equipment that is safe, so they have minimum test requirements written into their specifications.

ADWEA and DEWA do it and, although they can’t be specific about who the manufacturer should go to, they do give examples as you need to go to a recognised body.

There are a number of certification bodies that verify the testing of electrical power equipment, such as KEMA, ESEF, SATS, CESI and Intertek, which last year acquired ASTA BEAB certification services. Mostly, they do not carry out the testing themselves, but instead collaborate with accredited laboratories.

Shankar Subramany, manager of an accredited high power testing laboratory in Ludvika, Sweden, owned by ABB, explains.

“We are a member of SATS, which is an independent certification body, based in Norway, with several member laboratories both for high power and high voltage. We carry out the tests for SATS and those tests are supervised by inspectors from SATS, which then issues the certificate.

Even though the test laboratory belongs to an equipment manufacturer, there is no conflict of interest, as Subramany continues:

The laboratory is owned by ABB, but at the same time the laboratory is accredited to ISO/IEC 17025, the international standard for the accreditation of test and calibration laboratories.

“According to this standard, the criteria are laid down as to how the laboratory should be organised, how it should function and what kind of quality systems it should adopt and, of course, the test equipment, test and calibration methods and so on.

“And one of the most important criteria is that the laboratory should function free from the rest of the manufacturing organisation. So we are organised independently from ABB as a manufacturer, we can say we are more or less autonomous from the company.

Furthermore, the laboratory does not just test ABB products; it also conducts testing for other high-voltage power equipment makers.

Privatisation trend

Previously, utility firms often operated their own testing facilities, but because of the trend towards privatisation and the breaking up of large utilities, using independent accredited laboratories and those belonging to manufacturers is becoming more the norm.

“Most of the utilities who buy equipment today like to have third-party certification because in the past some of them owned their own laboratories and had their own competent people to do the testing,” says Subramany.

“They could buy equipment from manufacturers and make their own tests, but all this has changed, a lot because of the privatisation of the utilities. Now they accept tests done in the manufacturer’s laboratory, but they like to have an independent certification body to send their inspectors to supervise the test.

In the case of Intertek, the process is a little different: “We don’t go and supervise the tests within our laboratories,” Diack-Evans explains. “When we assess the laboratory as being suitable to test equipment for the purpose of issuing our certificates, we train one or more members of their staff to become observers.

This is an elite group of highly qualified engineers within the laboratories whose sole responsibility is to ensure that the tests are performed correctly. Their name also goes on certificate and they sign it.

“However, the certificate is rigorously reviewed before it is issued by expert Intertek engineers. When everything is satisfactory only then is the certificate signed by a senior member of the technical staff, integrally bound and sealed and sent back to the laboratory for presentation to the client.

Uniform testing

Certification bodies, operating in the field of high power testing, are usually members of the Short-Circuit Testing Liaison (STL), a voluntary organisation, which aims to harmonise the way product safety standards are interpreted and ensure that the tests are conducted and reported in a uniform manner.

An accredited laboratory will conduct any test requested by the client, but each laboratory should carry them out in the same way. “In our laboratory, we perform all kinds of short-circuit and switching tests,” says Subramany. “We test all high-voltage products, that is all products rated more than 1 000 volts up to 800 kV, including transmission and distribution products, like circuit-breakers, surge arrestors, power transformers and disconnectors.

“We test for their short-circuit performance to see how they behave during an exceptional condition, when failure occurs somewhere in a network and a short-circuit is created, to see what happens when very huge currents flow through this equipment and how they withstand the effects of the short-circuit.

A short-circuit can happen anytime, but the equipment should be able to continue its normal function when the system is restored.

“We also perform switching tests to simulate certain conditions like when the circuit-breaker is called upon to switch a large capacitor bank, an unloaded line or an unloaded transformer – when the current is not so important but the switching overvoltages could be critical for the equipment.

“And of course we have some other auxiliary test facilities like temperature-rise testing and mechanical testing also in our laboratories.

To be able to carry out such tests, naturally, the laboratories need a vast amount of specialist equipment. “It requires a very large test facility in order to simulate such fault conditions in the laboratory environment,” Subramany continues.

“So we have large generators to produce the very high short-circuit power for a duration of a few seconds.

With our generators, we can simulate about 4, 000 MVA of short-circuit power. For circuit-breaker testing, we also need large banks of capacitors and use a special test method, known as the synthetic test method, by which we can simulate the short-circuit power of more than 50, 000 MVA in the laboratory.

Type-testing

Given the nature of the tests carried out and the amount of power used, it is not surprising that it is very costly for manufacturers to have their equipment tested by a third party.

Diack-Evans says: “High-voltage power labs are very expensive to run.”

In the UK, it cost  £5, 000-7, 000 [US $10, 000-14, 000] per day for testing, and short-circuit tests alone on a piece of high-voltage equipment could take two or three days.

There are no longer any high-voltage test facilities operating in the UK; the last one shut in 2003. Similarly, there are none at present in the Middle East, with most testing for the region being carried out in India or at manufacturers’ laboratories where the equipment is assembled.

Due to the high expense of testing, most manufacturers cannot afford to have each individual product tested, so testing of a typical piece of equipment is the most standard practice, so-called type-testing.

A type-test proves the design and construction of a piece of equipment, which then forms the reference for other assemblies.

A type-test certificate tells a purchaser that its product or a product similar to the one it will buy performed as expected in a network when tested. It is not necessarily a test of the actual equipment the buyer will receive.

Once issued the type-test certificate remains valid indefinitely, unless a major technical or design change is made.

The high cost of testing also means that not all tests on high-voltage power equipment are third-party certified to prove that the product meets the requirements of all requisite safety standards. Rather, it is usually subjected to a selected number of tests, such as short-circuit, temperature-rise, and dielectric-strength tests.

Certification bodies also offer full certification, whereby the manufacturer’s facilities and products are more regularly inspected and tested. But in the Middle East, type-testing is the preferred option.

Manufacturers generally request tests which prove conformity to published standards such as the European International Electrotechnical Commission (IEC) standards, and the American Institute of Electrical and Electronics Engineers (IEEE) standards, but other regional and local product safety tests can also be conducted.

Increasingly, however, tests results carried out to IEC or IEEE standards are becoming globally accepted. This is also the case in the Middle East, which imports a lot of power equipment from Europe and the US.

“There is big demand in the Middle East for third-party testing,” says Subramany. “Many of the tests we perform, certified by SATS, are for equipment which is then sold to utilities in the Middle East and SATS certificates are accepted by the utilities there.

“Since the products coming into the region come from all over the world, it would be impossible for the buyer to get everything tested at one place in one test laboratory, so they have it tested at different locations. If the manufacturer has its own laboratories and uses third-party certification the buyer can have more confidence in the equipment.”

Diack-Evans agrees that third-party testing is growing in the Middle East. He recently relocated to Intertek’s office in Dubai to develop the business in this region and India. Part of his role will be to provide technical support to manufacturers who have not experienced the certification and testing process, but who are being asked to provide type-test certificates for their equipment.

The benefits

Yet if there is no legal requirement for third-party testing why should manufacturers bother to go to the expense? For Subramany and Diack-Evans the answers are simple.

For manufacturers, the main benefit of third-party certification is to demonstrate compliance with given product safety standards. This in turn makes products easier to market and, in particular, to export.

On top of that, independent testing can provide greater protection to equipment suppliers when issues of liability arise in the event of a power plant seriously malfunctioning. This is especially the case for equipment which may be installed for years before being called on to operate, such as circuit-breakers.

Utility companies, for their part, can have greater confidence in the safety and reliability of a power system if the installed equipment has been tested in an accredited laboratory and supervised by a third party.

It is not just a question of safeguarding a capital-intensive investment, but one of protecting the public from the potential dangers of defective or counterfeit equipment, and of providing a reliable electricity supply, with minimal outages.

Failure to carry out third-party testing has the potential to harm the profits and destroy the reputations of manufacturers and utilities alike.

“In the event of a fault within the transmission and distribution system, the equipment that is there to operate under such circumstances needs to operate in a safe and reliable manner. The equipment has to operate to clear the fault. This is the whole reason for short-circuit testing,” explains Diack-Evans.

“As systems get bigger, the demands placed upon them get bigger, and you don’t want any equipment operating under those conditions to blow up. If a maintenance engineer happens to be walking past such equipment in a control room at the time when it is called to operate under a short-circuit condition and it blows apart, the debris will cause serious injury or even death.

“There is no legal obligation to carry out third-party testing but it is necessary,” Diack-Evans concludes. “It is duty of care.