The Weakest Link?

The practical meaning of Totally Integrated Power can be experienced hands on at the Siemens Airport Center in Fuerth, Germany, where typical airport systems are operated in their ‘natural environment’. (All-Siemens)

Manfred Weiss from Siemens AG Industry Automation division underlines the importance of guaranteeing an airport’s power supply.

The practical meaning of Totally Integrated Power can be experienced hands on at the Siemens Airport Center in Fuerth, Germany, where typical airport systems are operated in their ‘natural environment’. (All-Siemens)

Airports belong to the type of buildings that demand maximum reliability in terms of their electric power supply.  An airport operator would regard total power failure as one of their worst nightmares.  However, despite these facilities’ incredible complexity, the task presented to their electrical planners can be solved by tailor-made infrastructure and software support.
As long as everything is working smoothly, passengers are blissfully unaware of the meticulous attention to detail with which an airport’s power requirements are planned, built and operated.  Any failure of an airport’s power distribution could be potentially disastrous as it affects the function and interaction of almost all of its safety-relevant systems.  To prevent such a terrible scenario occurring, airport planners can choose between various tried-and-tested supply concepts.  At Siemens the integrated approach to the task of power distribution has proven particularly important and is consistently implemented in our Totally Integrated Power (TIP) concept.
 
Priority-graded distribution
Large airports, such as Frankfurt Main, require a connected load of more than 60MW.  This is generally supplied from redundant transformer stations via several ring feeders on what in engineering terms is a medium-voltage level.  Corresponding transformers, such as the Geafol type, cast from resin, provide the low-voltage main distribution boards within the various airport sections.  The concept is based on pre-determined priority levels.
Siemens’ Manfred Weiss believes the various safety requirements can be best achieved with integrated systems.

For the power requirements of maintenance hangars or baggage conveyors, the standard mains supply is sufficient.  However, an increased safety level is required for its terminals, fire department, loading zones, car parks, emergency lighting systems and the railway station.  Should a fault occur, a safety supply is provided via emergency power generators, which will give the recognized safety-relevant areas electricity within 15 seconds.  Frankfurt’s navigational aids and ATC tower are deemed to be the most safety critical areas and these call for power failure response times of less than a second, or even uninterrupted power supplies.  Achieving such priority-graded power distribution is only possible when planners have the necessary tools and systems to account for these special safety requirements.
 
Planning, dimensioning and documentation
Siemens built a special Airport Center (AC) in Fuerth, Germany, which allows practical testing of its airport system solutions.  From the car park barrier to the tower, the AC contains and simulates all the important elements of a modern airport, in fact the only thing it lacks are real aircraft.  Its facilities not only allow for endurance tests of airport-specific applications, but also enable the testing of individual systems.  Their performance under extreme conditions – provoked by deliberate failures – is established without endangering anyone.
The busbars are directly connected to the Sivacon S8 low-voltage power distribution board via corresponding adapters.

If the systems are not dimensioned correctly and matched with each other, in a worst-case scenario, a simple short circuit in a power socket outlet can bring an entire airport terminal to a standstill.
The simultaneity factor – a figure used to calculate the theoretical total power consumption of a number of devices under realistic conditions – plays an elementary role in dimensioning.  For the electrical engineers amongst you, this figure generally lies at around 0.8 within airport facilities.  However, this value will vary depending on an airport’s layout, and planners will require significant experience in order to correctly assess the simultaneity factor.
Our Simaris design dimensioning software, which was certified by the TÜV Berlin technical inspectorate, offers valuable planning support in terms of the selection, dimensioning and the setting of values for all the required devices – from the medium voltage supply to the socket outlet.  Its easy operation via familiar Microsoft Windows interfaces and its workflow, which provides fast and safe results, contributed to its success as a dimensioning tool with planners of safety-relevant power distributions.  Around 1,000 licences for the Simaris design software have already been sold.
 
Plan in half a day
The Simaris system selects the best components from an integrated product database that contains all the detailed technical information and then fits them into a parts list or ‘network image’.  This data pool then becomes the basis for the planning documentation or power calculation, and can be easily converted into other formats such as Microsoft Excel, Word and DWG.  Once all the information required for the calculation is available, the planner can then simply prepare the complete electrical and construction plan of a subsection in only half a day.
Taking into account the all-important International Electrotechnical Commission (IEC) rules and their German (VDE) equivalents for the dimensioning of circuits, the software automatically determines the required selectivity of each protective element in relation to all the others that will follow within the set up – irrespective of the supply route.  Working from graphical layouts of the calculated power-time characteristic curve and the calculated selectivity ratings, planners can immediately see the accuracy of their work and I believe that these tools should form part of a planner’s basic equipment whether they work on residential, functional or industrial buildings.
 

Busbar trunking systems, such as the Sivacon 8PS by Siemens, significantly reduce systems’ fire loadings. In comparison to cable solutions, the easier and faster installation process compensates for their initially higher costs.

Detailed tender documents

The results of the planning process with the Simaris design tool can be used to accept invitations to tender.  The planner can be provided with the required tender texts, application manuals and further valuable information, by the electronics supplier via the company’s website, www.siemens.com/tip
 
Busbar systems
The power supply’s reliability can be further improved by replacing cable-based power set-ups with busbar trucking systems, such as the Sivacon 8PS.  We believe this offers numerous advantages, including a significantly reduced potential fire load.  Instead of the comparatively massive insulation required for wires and plastic coverings of power lines, busbar trunking systems only need to be covered with a thin lacquer coat.  Moreover, they only need much smaller wall ducts, making the job of sealing them a much easier and safer task. For this purpose, the manufacturer offers compact fire barriers for the various busbar types and sizes.
 
Cost-neutral
Busbar trunking systems are particularly suitable for the main supply routes of widely spread electric mains that are commonly found at airports.  They enable much faster installations and provide engineers with a highly flexible method of working.  The busbars are provided with standard connection points in small distances of only 19.68 – 39.37in (50 to 100cm).  Moreover, Busbars offer far better EMC (the unintentional generation, propagation and reception of electromagnetic energy) compatibility with high power loads than several parallel cable systems.
Siemens’ Geafol cast resin transformers are often employed in very safety-critical buildings, such as airports.

For the end customer, the airport operator, such solutions are cost-neutral because the expenditure on busbar trunking systems is compensated for by much-reduced wiring costs.  In addition, electric cables with halogen-free outer coverings are commonly used at airports, so by comparison this also makes ‘simple’ electric cables a far more expensive option.
The installation company also benefits from the use of busbar trunking systems, as no special training is required for those sections’ attachment and connection.  For example, the screw for the safe connection of the busbars, (ie the individual conductors) features two hexagonal nuts on top of each other.  The installer only has to tighten these nuts until the upper hexagon nut tears off at the predetermined breaking point.  The busbar is thus pre-tensioned and fixed with the required torque of 80 Nm.  Furthermore, busbars are easily adjusted to an individual building’s conditions by means of special shaped parts routed to a room in a three-dimensional manner.
 
Easy connection
The connection of the Sivacon 8PS busbar trunking systems to the low-voltage main distribution is also extremely easy via special adaptors.  The new generation of the Sivacon S8 power distribution boards allows for the main busbars to be positioned on both the top and bottom of the board, providing its users with maximum flexibility in terms of busbar routing.
The new S8 boards are not only type-tested and certified as standard, they are also arching resistant thanks to a top plate which gives pressure relief.  Safety was the most important aspect of the control cabinet’s redesign, which is underlined by the section division.  The busbars and their transition points to the cabinet are also type-tested.
 

A central fixing screw holds the individual busbar sections together. The correct torque of 80 Nm is set via a predetermined breaking point on the nut instead of via a torque spanner.

Fast commissioning

Our Sentron 3WL circuit breakers can be integrated and connected into the low-voltage main distribution cabinets.  The selectivity parameters of the trip units are taken from the scheme calculated by the Simaris design program and digitally loaded via data transmission, or directly set on the device via a rotary button.  In my opinion, this proves the advantages of integrated system solutions based on TIP.
 
Conclusion
The significance of the power supply in airports is proven by figures.  Frankfurt Main has an annual power consumption of 579 million kWh.  More than 51 million passengers, 1.75 million tons of freight and roughly 118,000 tons of airmail are handled every year.
Such busy operations demand a highly reliable power supply, so Siemens continuously works to iron-out any ‘weak links’.
The advantages for planners and airport operators are obvious.  Consistency generates transparency – and transparency generates safety.