Feature Hazardous Area Equipment
Making connections in extreme environments
As Stephen Thackray of Marechal Electric explains, all marine environments present extreme challenges for electrical safety and the skill is in matching the features of an electrical connector to each application
Left and below: the Shark-Fin latch on Marechal DXN self ejecting DECONTACTORs
Load break flexibility The DECONTACTORs’ ability to allow the disconnection of a plug from a cou- pler socket whilst still on load was central to DRILLMEC’s decision to approve the DECONTACTORs. As a manufacturer of drilling rigs for
lying idle. Personnel will be ensuring that all essential battery powered equip- ment onboard is fully charged and ready to save lives.
U
Of course the charging cable needs to be disconnected from the supply before the lifeboat is launched. Until now many such connectors had to be manu- ally disconnected prior to launch. Now a self ejecting connector is available which disconnects automatically via tension on the cable as soon as the lifeboat launch is activated. Marechal’s Ex range of standard and self ejecting DECONTACTORs use spring loaded silver tipped contacts which meet head-on with the plug con- tacts. The plug is held in the socket against the force of these spring contacts by means of a socket latch. Pressing the latch releases the plug, on load. Being a modular system, a coupler socket can be ejected from a fixed male inlet as well. A ‘shark’s fin’ latch is fitted on the
DXN self ejecting DECONTACTORs. This latch is mounted on the socket for ejecting sockets from inlets or on the plug for ejecting plugs from fixed sock- ets, as pictured here. The latch is con- nected to the power cable via a tension cord. When the lifeboat is launched, tension on the power cable is trans- ferred to the cord which in turn lifts the shark’s fin latch to release the plug. The self closing cover on the DECON- TACTOR socket then closes. In addition to being used on
10
ntil the moment that a lifeboat is called into action to evacuate personnel
from an offshore drilling rig or a ship, it is not
lifeboats, the compact and watertight DXN DECONTACTORs can also be used for mobile containers, skid mounted equipment, cranes, truck hook-ups or any other type of portable equipment used in the marine or oil and gas industries.
Small footprint
Offshore drilling rigs also present the challenge of very tight space con- straints. There simply is no room to spare for bulky connectors.
For Singapore-based PPL, the answer to the space problem was to approve and install three separate types of Marechal DECONTACTORs on its Pacific Class 400 jack-up rigs - collaboration
between Marechal
Electric and DRILLMEC engineers enabled different connectors to be specified for specific functions on the rigs. Explosion-proof DXN and weather-proof DSN DECONTACTORs were specified, in addition to custom- made SS 316L enclosures fitted with 250A DS2 type and 400A CS type single core connectors.
The smaller than average footprint and robust design make these connec- tors well suited for the tough offshore rig environment. All of the materials used
in the manufacture of the
DECONTACTORs are resistant to the salt
laden marine atmosphere and
chemicals on the rigs. The ability to operate over a wide temperature range and withstand mechanical shock will ensure that the DECONTACTORs will provide long term reliability despite the extreme environment.
DECEMBER/JANUARY 2014 Electrical Engineering
water, oil and gas, the manufacturing schedule for each rig is critical. The DECONTACTORs’ integral switching mechanism protects DRILLMEC’s workers and customers by ensuring that any arcing is contained within the socket’s arc chambers. This high level of protection also means that the DECONTACTORs can be disconnected and connected quickly and easily on load by both skilled and un-skilled staff during equipment commissioning and subsequent operation in the field. This flexibility allows DRILLMEC to significantly reduce plant mainte- nance time and cost without compro- mising safety. With a connector range from 5A to 700A available, DRILLMEC have been able to approve MARECHAL’s DSN and DS industrial connectors for applications up to 150A, and the inter- locked single core SP4 connectors for applications up to 250A.
Rugged connections In such heavy duty applications, the use of rugged design features and high quality materials such as the silver nickel, spring loaded butt contacts, means that DECONTACTORs provide excellent long term service even in temperatures from -40°C to 60°C with ingress protection of IP66/IP67.
Marechal
www.marechal.com/en T: +33 0145 116 000
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