The Perfec Weather For Cable Testing!

In the future, the only way to test long submarine cables in offshore wind farms will be via resonance testing. HIGHVOLT has therefore developed a new testing system capable of withstanding the harsh conditions out at sea.

Consider this scenario: Shortly before the winter season, an unknown problem arises at an offshore wind farm. With so little time before the end of the testing season—and in this wea­ther—no one is able to visit the site to carry out a high-voltage test. So the winter storms rage for months and the rotors are in permanent motion—but it all goes to waste.

The electrical power that is generated cannot be used on land. The bad weather and low temperatures mean that no work can be carried out on site, so the engineers have to wait until at least April before they can visit the wind farm and find out what the problem is. In the meantime, the wind farm operator keeps staring at the calendar: For every day that they are unable to supply power to the grid, they lose more and more money. When will it finally be summer again?

So what is needed are practical, weather-proof offshore testing systems.

Conventional testing systems for inspecting cables are not designed for the conditions at an offshore platform. When exposed to the salt in the air, as well as rain, snow, and rough seas, they cannot operate reliably. Solutions that have proved useful for on-site testing on land—the use of tents, for example—are not going to be much help here. Furthermore, transporting materials and people with special ships or helicopters is difficult and has to be planned well in advance. The window of opportunity where the wind farms are actually accessible amounts to only a few months of the year. So what is needed are practical, weather-proof offshore testing systems.

Resonance testing

In response to these two factors—the weather at sea and the IEC standardization—HIGHVOLT has developed an offshore testing system which fulfills the requirements for on-site testing on the high seas. The technology is based on the tried-and-tested HIGHVOLT resonance testing systems, which have long been in use in hun­dreds of applications all over the world.


The resonance testing method reproduces the load on a cable in normal operation at nominal voltage and at approximately grid frequency. A resonant circuit comprising a test inductor (inductance) and test cable (capacitance) is established for this purpose. The variable frequency (10–500 Hz) of the test system supply is automatically set to the resonance frequency of the test circuit, which minimizes the required feed-in power.

Over half of all problems are due to installation errors. These can be reliably detected by means of resonance testing.

The necessary adaptations have been made with outstanding attention to detail: The engineers in Dresden checked the suitability of every single component for offshore use and upgraded or redesigned them as necessary. Examples include the use of corrosion-free materials which are extremely resistant to salt water spray, shielded and offshore-certified plug connectors, and a gas-insulated module for reliable, fault-free connection of the system components and voltage measurement.

With this test­ing system, HIGHVOLT provides wind farm operators, cable manufacturers, and testing service providers with the flexibility they need to safeguard the functioning of complex offshore electrical infrastructures on a contin­uous basis.

The engineers in Dresden checked the suitability of every single component for offshore use.

And if something should go wrong shortly before the end of the next testing season, this solution will enable them to test the systems quickly, rectify the problem and harness the power of the winter winds to the fullest possible extent.


If you are looking to increase the reliability of your offshore cable infrastructure,
Katja Vogt will be happy to answer your questions.

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