Feature ?????????? Safety
A window of opportunity for live inspections at Stansted airport
Inspection of low voltage equipment at London Stansted airport needs to be undertaken in a time window of just four hours per night. However, the installation of IRISS CAP infrared inspection windows has not only improved safety but has drastically reduced inspection time
A
s London’s third busiest airport, Stansted currently sees around 17.5 million people pass through the terminal building
each year, although it has permission to handle 35 million passengers per year. While night operations largely involve Ryanair and easyJet aircraft returning to the base, as well as cargo flights, the early hours of the morning provide a relatively quiet period for planned maintenance. But, passenger processing normally starts around 3.30am and all electrical systems must be running by then.
The reliable and continuous opera-
tion of the passenger terminal has to be assured for much more than just day-to- day working – the airport needs to be ready for every eventuality, whether the cause is bad weather or a security alert. This therefore puts the maintenance teams responsible for the reliability of all low voltage equipment under huge time pressure.
At best, engineers had four hours per night in which to conduct predic- tive maintenance inspections. By the time they had made the system safe, this window of opportunity reduced even more. As a result, the entire inspection cycle was significantly protracted and no system could be checked under load. However, while parts of the high voltage network can selectively shut- down without compromising the oper- ation, the low voltage equipment does not have similar capacity.
Engineering compliance manager, David Potter, who is responsible for
18
strategic planning and maintenance of electrical distribution on site, both high and low voltage, said: “Our high voltage network is owned and man- aged by UKPNS but maintenance of low voltage equipment is down to our own engineering teams. We agree the maintenance schedule with the Airline Operators Committee three months in advance and our Maximo planning system flags up what needs to be inspected each night, but in every case it’s a race against time. Nevertheless, this work is vital.”
Maintenance
The electrical infrastructure at London Stansted Airport is huge. Power is brought onto the site at 33kV and transformed down to 11V; and the low voltage network feeds all manner of systems in the main terminal building, typically IT and baggage handling. Any unexpected interruption in the power supply could therefore have serious consequences.
The potential cost of failure is also huge: under the Service Quality Rebate scheme (SQR), the airport has to pay compensation to its customers, the airlines and handling agents if it fails to meet an agreed level of expectation. Although efficient maintenance had so far prevented serious low voltage system failures, Potter wanted greater assurance and had considered the use of infrared windows to complement outsourced thermal imaging surveys and to allow live inspection. “A small crystal window may have been fine for small switchgear but
SUMMER 2013 Enclosure & Safety Solutions
the size of our equipment meant that we would end up with so many windows, our substation would look like a submarine,” commented Potter. “Even if it had been viable from a practical standpoint, the cost would be huge. And crucially an individual window would be too small to allow the all important inspection of an entire busbar.” Potter, however, spotted a feature in a trade press magazine on IRISS Custom Application Product (CAP) Series infrared windows made from transmissive polymer. This fully impact resistant material allows the window to be any size which is perfect for applications involving large switchgear.
Installation
IRISS IR windows enable safe inspection
Initially IRISS considered the project in two phases, but the low cost allowed substations serving the termi- nal block to be fitted with windows in
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28