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"In 2011, we replaced an existing purely mechanical lift system at our site in Ludwigshafen," reports Michael Krauß, Head of Building Organisation at Sparkasse Vorderpfalz. "There are two passenger lifts with a nominal load of 650kg each and one goods lift with a nominal load of 1.1t. The special feature is that the group of three travels in a common shaft. The lifts open up the whole house. The system is controlled in such a way that part of the floor is only accessible to employees. And if necessary, further floors can be blocked at any time for any period of time. The relevant data is stored online by the lift manufacturer. One phone call is enough.”

The requirement profile of the Sparkasse was clear in advance. The existing access control system for the employees, which consists of card readers, was to be transferred to the lifts so that access to the bank and operation of the lifts works via the existing chip card. However, the technical implementation turned out to be not so easy: the elevator manufacturer could not offer a bus cable that would have made it possible to connect the existing card readers. The solution came from the electrical installation company Keipp from Ludwigshafen, which carries out a wide range of electrical and installation work for the Sparkasse.

They extended the access control system to the lift system. The existing card readers were connected via a special chainflex® cable.

The bus cable (purple jacket) would quickly break due to its own weight. The special cable with the reinforced black jacket, designed for hanging applications, absorbs the high forces.

Technical advantages of the special cable
 
The lift system features a special chainflex® cable, CFSPECIAL182.045, for hanging applications from igus® GmbH, based in Cologne Germany, which exceeds the requirements of all applicable standards and directives, and in tensile strength it significantly exceeds these requirements. The CFSPECIAL series introduced in 2012 expands the standard product range by adding cables for highly demanding tasks. This series also includes special cables, such as for the rail industry, and cables with high tensile strength.
The special cables offer a wide array of benefits. They provide solutions for applications that go beyond normal energy chain applications. The growing product range of special cables is geared towards the requirements of customers from all industries, for which specific solutions are developed and tested.

"Bulletproof" special cable

The special cable for data transmission in the lift system hangs freely in the shaft and easily absorbs the weight forces that occur. It has the same four-pair core structure as a normal Ethernet cable and has a TPE inner jacket and an extremely rigid shield braiding. The difference to standard bus cables lies in their jacket structure. The black outer jacket is made of a low-adhesion, highly abrasion-resistant PUR compound with an embedded aramid Kevlar fibre. "The material is similar to that of a bulletproof vest," says Muckes. The technical structure sounds simple, but it is extremely sophisticated: the special fibre is braided over a thin jacket. This sinks into the material during the subsequent production of the outer jacket and permanently absorbs all external forces.

In the test laboratory it could be proven that the special cable is around 15,000 percent above the standard required in the corresponding DIN VDE 0298 in the tensile test. Pulled with 2,919N, the cable is not torn off and the data transmission remains permanent. The cable length in the system is 74 metres.

The special cable is freely suspended in the lift shaft. It is reliable and works any problems.

Error-free data transmission
 
This particularly durable special cable with aramid fibre was originally developed for storage and retrieval machines used in high-rack facilities with racks up to 100 metres high. At this height, data transmission problems may occur with standard cables. The chainflex cables also demonstrate their performance capacity in movable camera systems in forklift applications where a camera is integrated into the fork arm and the cable is wound around drums. All these applications have in common that data transmission must occur error-free and safety is of great importance. Moreover, the processes must never come to a stop. "The lift just has to work. In order to ensure smooth customer traffic, it cannot stop unexpectedly," says the Director of Facility Management at Sparkasse.