Designing a UPS solution for an offshore rig off the African coast

An Uninterruptible Power Supply is mandatory on oil rigs: for safety reasons, the signal lighting must be operational at all times. Tasked with designing a UPS solution for an offshore rig off the African coast, R. STAHL was faced with three challenges. The UPS system not only required protective measures against explosive atmospheres, but also had to be adapted to the great heat and maritime climate at the rig's location.

Complete blackouts or malfunctions in the mains power supply, such as frequency fluctuations or overvoltages caused by lightning strikes, must be safely bridged on oil rigs. Above all, functioning signal lights are not only essential for smooth operation on the rig, but also for the safety of all nearby ships and airplanes. Therefore, the position lights must not fail under any circumstances. The platform, which is situated off the African Atlantic coast and whose cavern is currently being used as a temporary store for natural gas, is usually supplied by means of a solar power plant. A battery-powered emergency grid was installed in parallel. In addition to the power supply unit, R. STAHL assembled further energy distribution components from its modular kit for UPS system solutions.

Beautiful weather, rugged environment
In addition to explosive atmospheres occurring occasionally (Ex Zone 1), the tropical climate and sea air had to be taken into account. The temperature on the platform often exceeds 35 °C, and occasionally reaches peaks of 50 °C. At such ambient temperatures, the operation of the charger for the UPS batteries, which generates a great deal of power loss, required special measures. In order to prevent overheating, R. STAHL installed the battery charger in the largest available CUBEx enclosure. Several special features ensure heat dissipation: by means of a patented cold plate technology, the heat is directly evacuated from the protective enclosure. The heat sink is attached to the side of the enclosure, allowing for easy access to the CUBEx unit during maintenance.

Illustration 1 (top left): Explosion-protected UPS systems from R. STAHL ensure a fail-safe power supply on offshore platforms by means of a battery unit. Illustration 2 (top right): Due to very high ambient temperatures, the explosion-protected enclosure was fitted with a heat sink and a fan. Illustration 3 (lower left): The Ex UPS guard ensures charger and battery monitoring which is explicitly required in Ex Zone 1. Illustration 4 (lower right): The distributor solution with a safe parallel feed, which ensures the continuous power supply for the lighting, is also suitable for hazardous areas.

Special features create turbulence
A stainless steel fan for hazardous areas with a motion monitoring function, which is installed above the enclosure, facilitates heat dissipation. The fan also had to be adapted for use in Zone 1 under extreme environmental conditions. The forced cooling is controlled and monitored by an intelligent control system: the operating mode of the fan is adjusted depending on the current ambient temperature. Thanks to these measures, a maximum power loss of 1,000 W can be compensated in addition to the amount dissipated through the enclosure surface by default. The considerable amount of exhaust heat generated by charging the batteries can thereby be released to the environment without compromising the operation of the charger.

Like in all other UPS solutions from R. STAHL, the required explosion protection for Zone 1 is ensured by a special feature which is unique on the market: an integrated Ex UPS guard monitors the functions of the battery charger and the batteries, which are also installed within the Ex zone, according to the ATEX directive and according to IEC/EN 60079 ff, thereby allowing for safe operation.

Continuous lighting with a double power supply In order to ensure a continuous power supply for the lighting, R. STAHL installed a distribution panel with a safe parallel feed from the standard power supply and the emergency grid. The lighting distribution panel features two interlocked inputs. Additionally, each outgoing line is separately monitored for ground faults. All functions can be activated from the outside, and the status of each outgoing line is clearly indicated by the position of the handle. By installing a combination of CUBEx flameproof enclosures (Ex d) and enclosures with increased safety (Ex e) connection chambers, R. STAHL was able to implement a very compact, weight-optimised system within the limited installation space on the offshore platform. All outside metal parts of the seawater-resistant CUBEx enclosures are made from SS316 stainless steel. This material requires no further surface treatment for use in maritime environments. Refer to page 83

100% process safety in hazardous areas: Modular UPS solutions in detail UPS solutions component range includes battery chargers, various explosion-protected rechargeable batteries (lead gel, NiCd, NiMH), charge monitoring technology including alarm annunciators, DC power distributors and inverters for various performance classes up to 3,000 VA. Additionally, R. STAHL provides a wide range of explosion-protected enclosures, such as the GUBox series which features Ex e connection chambers. R. STAHL also provides modules with user-specific explosion protection types as required.

For further information, e-mail:kerstin.wolf@stahl.de  Refer to page 83

Most powerful air hoist lifts 125 tonnes

What is believed to be the world's first air operated hoist with a lift capacity of 125 tonnes has been manufactured by materials handling and lifting specialists J D Neuhaus. This is the most powerful unit in their EH range of handling equipment.

Designated as an EH 125 monorail hoist, the unit operates from a 6 bar air pressure and is equipped with 10kW and 2.8kW rated motors for the lifting and traverse functions respectively. In standard format, the hoist is supplied with a six double-chain mechanism providing a three metre lift at speeds of 0.30 m/min within a full load, and 0.38 m/min on lowering. Horizontal travel speeds of 6 m/min are achieved with maximum load and 8 m/min when unloaded. A two metre length flexible connection is supplied with an ergonomic multi-function pendant controller for precise, infinitely variable control of the lift/lowering and traverse operations for safe, accurate load placements.

Picture shows the new EH 125 lifting unit in the test stand.

The hoist is designed for operating within heavy industries such as steelworks, cement, chemical, power generation and shipbuilding plants as well as the oil and gas markets. The low-headroom design ensures that the hoist can be used where minimum operating space is available, while an Ex rating ensures suitability for use in hazardous areas where there is a potential risk of explosion. The product is 100% duty rated while also being insensitive to humidity and dust laden atmospheres, and can operate within a temperature range of -20°C to +70°C.

As with all the JDN high performance lifting products, standard safety features include a fail safe brake to hold the load in the event of air supply failure, an emergency shut-off valve, anti-climb and anti-drop devices together with an emergency lowering device. Optional accessories include overload and increased spark protection, two speed trolley travel control and rack and pinion drive. Non-standard lift heights and remote radio-control operation can also be accommodated.

Further information, e-mail: info@jdneuhaus.co.uk or view website: www.jdneuhaus.co.uk  Refer to page 62   

The EUROBLOC VT family from Verlinde
has grown with the introduction of the VT10 and 11

The EUROBLOC VT family has grown with the introduction of the VT10 and 11. These are electric open winches designed to lift loads of between 32,000 and 160,000 kg. Fitted with speed control as standard, they have a 103 metre maximum height of lift.

The EUROBLOC VT 10 and 11 range offers the best possible operating area for the hoist unit. In fact, its central hoist design gives it huge load capacity without the need for twin pulley blocks. The very large drum diameter helps reduce track widths and hook approach distances, whilst extending cable life.

The EUROBLOC VT 10 and 11 are also notable for their fast lifting speed, which can be adjusted using a closed-loop control. In addition, optimal positioning of the rollers on the trolley helps to distribute the load more evenly across the bearing structure, and an innovative cable guide system helps to reduce strain on the cable, extending its service life.

Safety features include a lifting brake, controlled by an intelligent monitoring system integrated into the speed control, which can detect slippage or jams. EUROBLOC VT 10 and 11 models also have a dual end-of-travel safety feature (limit switch with high/low position detection and pulley block operated end of travel safety switch). Finally, a travel limit switch is included as standard, plus hoist monitoring with the VERLINDE MT2 system.

The high-efficiency hoisting motor has a 40% duty ratio. Components used for the range are IP55 and IP66 classified. A standard format maintenance platform is offered as an option, along with a double brake and pressure roller.

For further information, e-mail: jean-yves.beaussart@verlinde.com  Refer to page 69

The EQUIBLOC AIR range of pneumatic
load balancers for loads of from 70 to 350 kg

The EQUIBLOC AIR range of pneumatic load balancers for loads of from 70 to 350 kg offers an even wider range of load hoisting and handling solutions for industry.

Delivered with all equipment and ready for "Plug & play" operation (control box fully equipped with distributor and regulator), EQUIBLOC AIR is quick and easy to put into service. Standard equipment includes an UP / DOWN control circuit, a 6 m cable, a spiral-wrap flexible control system duct, a valve box-type control interface and an automatic-type hook. The EQUIBLOC AIR range consists of 5 models.

EQUIBLOC AIR stands out for its high degree of safety
1) Balancing by pneumatic measurement of load. 2) UP / DOWN control box integrating balance mode switch. 3) Detection of underload. 4) Locking of grab (if applicable) when load is lifted.

Numerous options are available
Various types of trolleys depending on bar sections (I-section trolleys, hollow steel section trolleys or aluminium EUROSYSTEM type trolleys). Rigid suspension systems, flexible pneumatic hose or even trolleys with flexible doors are available. Also available are load gripping tools (mechanical, vacuum or magnetic gripping systems) built to comply with specification sheet, if required. For Zone Ex, Zone 1 or Zone 21 application, specific models are also available.

Due to its design, maintenance of our balancer is very easy and simple. For instance, the hoist rope is changed by simply opening the cabinet and the cylinder seal is changed without fully opening the box.

Advantages of pneumatic balancers
1) No abrupt movements during lowering and raising. 2) No need for electricity and therefore a greater degree of safety. 3) Flexibility of operation; reduction of operator fatigue; reduction of musculo-skeletal disorders. 4) Fast and precise manipulation. 5) Effortless load travel. 6) Handling by a single operator. 7) Ergonomically designed control box. 8) The hook control is linked by 2 spiral-wrap hoses. 9) Extremely quiet running provides best operating convenience.

For further information, e-mail: jean-yves.beaussart@verlinde.com  Refer to page 69