Saving time with decontactors
The use of decontactors has offered impressive time savings for maintenance operations at an InterGen operated gas fired power station.
Spalding Power Station is one of the newest gas fired power stations in the UK, using combined cycle gas turbine technology to generate up to 860 MW of electricity. The facility is located in Lincolnshire, and is one of a series of plants owned and operated by InterGen.
Modern electricity production depends on regular maintenance. One of the procedures that must be undertaken to gain service access to the plant’s turbines is to remove part of the roof directly above the generators. However, to be able to do this it is necessary to disconnect many hard-wired cables in the roof area. This is a labour intensive operation, typically taking two men one and a half days, with most of this time being spent disconnecting the hard-wired cables. Once removed and after the maintenance work has been completed it then takes a further one and a half days to replace the roof and rewire the cables and perhaps another half a day needs to be set aside for faultfinding.
The whole operation is complicated and difficult and significantly, it is also very expensive.
It was important, therefore, for the engineers at Spalding to find a more efficient and economical solution that would reduce the costs associated with the roof removal operation. The solution lay in the way that the roof cables were terminated. If the hardwiring were to be replaced by another method of connection that could simply and easily allow disconnection and reconnection with security and continuity, then massive savings to the work required could be made.
And the answer was…
A decontactor offers just that facility! It is an electrical socket with an integral switching mechanism that offers the function of an isolator and a removable connector in one product. When the Marechal decontactor socket was demonstrated to the Spalding maintenance team they immediately appreciated the cost-saving potential. By replacing all of the hardwiring with decontactor connectors of various types, disconnection of the different roof cable types was made possible in seconds, and could even be undertaken by multi-skilled staff. Power (250A), multi-core and single core cables were all accommodated.
The on-site contractor completed the installation of Marechal decontactors in the first roof at Spalding during February 2009. Not long after this, emergency maintenance required the roof to be removed. This was successfully undertaken in just over 7 hours. This significant reduction in time and labour led to the second roof being up-dated with decontactor connections in November 2009.
A simple solution
Any suitable electrical equipment can be safely connected and disconnected in seconds when fitted with a decontactor. The design of the product means that by simply pressing the socket latch the plug is released which then ejects into a parked position - isolated. The plug can then be removed and the socket padlocked off, if required, creating visible isolation.
The Marechal decontactor range is available in ratings from 20 to 250A, and with auxiliary contacts also an option (plug in/out signals, linked to a contactor etc) both mobile and fixed equipment can be isolated in seconds, saving cost every time. It complies with both IEC/EN60309-1 (Plugs & Sockets) and IEC/EN60947-3 (Air Break Switches).
Since Spalding have discovered this method of reducing essential and emergency maintenance costs, a number of other generating plants across the UK and Europe are also considering using the decontactor in similar applications.
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