100% process reliability on platforms
UPS to the customers' exact specifications
When R. STAHL set about engineering an uninterrupted power supply (UPS) for an offshore system off the coast of Africa, it found itself confronted by three unique challenges:
- It had to provide protection against explosive atmospheres
- It had to provide protection against heat
- And it had to provide protection against the maritime climate
Complete power failures or disruptions to the mains power supply had to be safely overcome on the oil drilling platforms, despite the extreme conditions. The customer turned to R. STAHL because they trusted us with this unique requirement.
Beautiful weather makes for tough conditions
Apart from the need to incorporate protection against the occasional occurrence of explosive atmospheres (Ex Zone 1) into the design, the tropical climate and the sea air also had to be considered. The platform is frequently exposed to constant temperatures of 35 °C and more. Every now and then, the temperature soars to as much as 50 °C. At such high ambient temperatures, operating the UPS battery charger poses a particular challenge as the power dissipation with this device is significant.
To prevent overheating, R. STAHL housed the charger in the largest CUBEx enclosure available. A number of special features were used to conduct the energy from the dissipated power away: This heat is transported directly out of the protective enclosure using a patented feedthrough (cold plate technology). To allow easy access to the CUBEx enclosure for maintenance work, this heat sink is attached to the side of the enclosure.
Special equipment to create air flow
A monitored stainless steel Ex fan installed above the enclosure assists with the dissipation of heat. This fan also required a special design to make it suitable for use in these extreme Ex Zone 1 conditions. The forced cooling is intelligently controlled and monitored; the fan's operating mode is adjusted depending on the current ambient temperature. In spite of the adverse operating conditions, these measures allow power dissipation of up to 1000 W to be compensated over and above the values normally emitted from the surface of the enclosure. The considerable amounts of waste heat generated by charging the batteries can therefore be dissipated into the environment without any detrimental effects on the charger's functionality.
As with all of R. STAHL's UPS solutions, the explosion protection prescribed for use in Zone 1 is provided by a special function: An integrated Ex UPS guard checks that the charger and batteries (which are also in the hazardous area) are functioning correctly in accordance with both ATEX directives and IEC/EN 60079 ff, thereby ensuring that they operate safely.
Uninterrupted lighting with parallel power supplies
To ensure that the lighting has an uninterrupted power supply, a distribution board with safe parallel power supplies combining the normal power supply and the back-up mains power supply was installed. The lighting distribution board is designed with two different power supplies, which cannot be used at the same time. In addition, each outgoing conductor is monitored separately for earth faults. All functions can be operated from the outside. The status of each outgoing conductor is clearly indicated by the handle position.
The use of Ex d flameproof CUBEx enclosures in conjunction with Ex e increased safety connection chamber enclosures allowed for an incredibly compact, lightweight design suited to the limited installation space available on the offshore platform. All the external metal components on the seawater-resistant CUBEx enclosures are made from SS316 stainless steel which has the advantage that it does not require any additional surface treatment for use in maritime environments.
100% process reliability in hazardous areas
R. STAHL engineers custom, application-specific uninterrupted power supplies (UPS) for oil and gas platforms and similar Ex environments in which 100% system availability is absolutely crucial. On unmanned platforms in particular, these systems ensure that, in the event of a power failure, power continues to be supplied for a specified period to the most important consumers, including valves, pumps, and navigation and signalling equipment such as GPS devices and flashing beacons. This allows data to be retrieved and saved in a coordinated fashion, as well as allowing the platform to be made safe.
Modular UPS solutions in detail
R. STAHL offers a modular system for Ex-protected uninterrupted power supplies with a wide selection of components. They can be combined in many different ways and, if required, can be designed with special equipment so that they are optimally adapted to the requirements of specific applications. The UPS solutions can be designed with continuous battery power supply or battery switch-over. R. STAHL's UPS systems allow connected devices to be independently powered and continue to operate for periods between 5 minutes and several hours. The modular system comprises chargers, various explosion-protected battery types, charge monitoring equipment including alarm indicators, DC power distribution boards and inverters for various power ranges.
R. STAHL also supplies a variety of different explosion-protected enclosures.
Apart from the modular system as a whole, R. STAHL can design custom explosion protection for individual modules to meet the customers' requirements and can provide the necessary certification. Using robust components and protective measures, the systems can be made to withstand even extreme conditions such as intense heat or cold, high humidity levels and atmospheres with a high salt content. If required, adaptations can be made to the power output and functions of custom systems at any time. R. STAHL offers help and advice at every stage of the systems' implementation and operation, from the project engineering stage through to delivery, commissioning and servicing.