Bennex has completed its second delivery of the Anguila high-power changeover switch (HPCS), which switches power between two subsea consumers without the need for costly or time-consuming intervention.
Three switches were delivered last year to Talisman’s Yme redevelopment project in the Norwegian North Sea, where they have been installed on three subsea production wells. The wells are fitted with dual downhole electric submersible pumps (ESPs), and the function of the switches is to direct power from one to the other. Yme is expected to come onstream later this year.
This application has been the focal point of the switch development, says sales and marketing director Jan Helge Telseth. But the technology also is relevant to other configurations of subsea machinery such as where there is a water injection pump and a pipe heating system, and both are needed only intermittently.
Use of the HPCS makes it possible to supply power to two users with a single power cable, cutting the cost of a second cable. Price is also the major driver in the case of the ESPs, says Telseth – the operator enjoys the economic benefit of being able to continue production at normal rates while arranging to retrieve and repair the malfunctioning pump when convenient.
One major challenge to developing the switch was making it free of partial discharge (PD), which otherwise would cause problems with the long-term reliability. To meet this challenge, the company established its own PD laboratory, which is also available for the testing of third-party equipment.
Further development of the switch is under way and includes increasing the rating from the current level of 6 kV to 12 kV. Bennex intends to bring an electrically operated version to the market – at present the switch is operated hydraulically. This is essential as operators look towards the goal of all-electric subsea systems. A third important development is to make the switch hot, allowing it to be operated without first taking the load down, as is the case now.
The switch, which weighs 300 kg (661 lb) in air, has been specified for several upcoming field developments, says Telseth. He is confident it will make an important addition to the subsea technology toolbox.
