Vintage ride gets some 21st century treatment
04 April 2013
Bakken Amusement Park in Klampenborg near Copenhagen is the oldest amusement park in the world and is home to one of the oldest roller coasters in Europe: the ‘Rutschebanen’, a wooden coaster built in 1932.
Fairground ride engineering specialist, Weert based KumbaK recently fitted this vintage coaster with new trains, brakes and a control system with safety functionality built in.
According to KumbaK senior engineer, Jeroen Uittenbogaart, the Rutschebanen was in need of an upgrade and the Bakken Amusement Park people wanted to make sure that this ‘crowd puller’ fully met the latest safety requirements.
“We chose a Rockwell Automation control platform at a very early stage,” recalls Mr Uittenbogaart. “An important reason for this choice was that Rockwell Automation is the standard for the control of roller coasters. The support Rockwell Automation offered played an important role too, and our relationship with the company goes way back.
According to Mr Uittenbogaart, Rockwell’s OEM strategy provided continuity for his company, plus a technical consultant who assisted with the test set-up as well as providing on-site training. “There was no margin for additional technical risks in the project and this is why we opted for this company’s proven technology.”
Safety through redundancy
A mandatory requirement for such a project is a risk analysis and evaluation, the outcome of which was that the roller coaster controller needed to meet safety integrity level (SIL) 3. KumbaK worked out the technical implementation of the design in collaboration with Jan van den Elzen, a project manager at Van Doren Engineers in Helden-Beringe. To achieve this safety level, extra emphasis was placed on redundancy, which applied to both the software and the hardware, as Mr Van den Elzen explains:
“The standard Allen-Bradley GuardLogix from Rockwell Automation includes integrated safety function blocks certified by TÜV. This is a very user-friendly feature for the programmer and once the function blocks have been programmed, they are ‘write protected’, which means you cannot inadvertently change them. And if you do, the controller will let you know.
“To program the safety function blocks for a safety project, a functional description is necessary in which various levels are defined. Level 0 is the highest level; this is used for emergency stops. Level 1 applies to the block-zone protection. If either of these levels is reached, the entire roller coaster will stop.
“Below these lies level 2, which applies to the sensor checks. The system monitors the sensors to make sure they are all working. Most of the sensors are installed in redundant pairs and are redundantly wired. When a signal arrives, the signal from the other sensor must also be received within a pre-defined time. If the second signal is not received in time, the safety controller will make sure that no other train enters the block-zone.
“The speed of the train is also monitored, and if the speed exceeds a pre-set limit, the train is stopped. There is also redundancy at the hardware level; in addition to the redundant implementation of the sensors, the number of actuators is kept at N+1. Our safety PAC is an Allen-Bradley GuardLogix programmable automation controller; in fact, it is both a regular controller and a ‘safety’ controller in one.
“An Allen-Bradley GuardLogix handles all the safety functions on both processors simultaneously. The controller continuously compares the speed and the outcome of the process with each other to eliminate any possibility of failure. We also use Allen-Bradley PowerFlex 70 ac drives, equipped with ‘SafeTorqueOff’ functionality, which are protected against uncontrolled restart. In the event of an emergency stop, power to the application is cut, after which it can quickly be restarted.” Mr Uittenbogaart again
“There is a considerable time saving for the engineering team. This is mainly due to the simpler, more efficient and more robust system. Thanks to Allen-Bradley GuardLogix we no longer have to use two controllers, nor do we require two output relays for the brake release.
“We now use fewer electromechanical components, such as auxiliary relays, which means there is less wear and maintenance. There is also less wiring as the control cabinet is much smaller. Moreover, we only have to perform the programming once – that in itself helps to reduce the possibility of mistakes.”
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