Bus cables for long travels and the alternatives

Jen Chen | September 15, 2021

Today I would like to tell you about a customer visit in recent weeks that prompted me to write today’s blog article. This is about the topic of bus cables with long travels.

The customer builds systems for processing foam materials. Amongst other things, this is about material handling between the various processing steps. These projects often involve long travels in which our e-chains and chainflex cables are used.

Long travels

In long travels, our products have to permanently withstand a heavy load.

But the mechanical resilience was not the issue at all at this meeting.

Because as soon as we start talking about long travels, the question of the maximum transmission length often arises, e.g. with a bus cable.

I learned that in the customer’s application with a travel of approx. 100m, a chain assignment was planned with motor cable, control cables and Profinet cable.

The transmission length

The subject of Profinet cable made me sit up and take notice. Why?

Not every cable is suitable for every transmission length. With an electrical conductor, we are always limited in the transmission length because the cable has losses over the long distance.

The longer the distance, i.e. the cable, the higher the loss of data or electrical energy that is conveyed over the cable. In principle, you can easily imagine this using the example of a hose. If the hose has holes, the same amount of water will not arrive at the end as flowed in initially. If we now define the number of holes per metre, for example, the amount of water that comes out of the hose at the end would depend on how long the hose is. Because of the holes, you now have a loss over distance.  In an electrical conductor, the holes can represent e.g. attenuation values or also disturbances from outside, which increase depending on the cable length and thus influence the loss over the distance.

The longer the travels, the greater the risk that data or electrical energy will not reach the end of the cable to the desired extent. Therefore, it is important to discuss these projects in detail, especially for applications with long travels. Applications with long travels mainly include cranes, gantries or long production lines. We will be happy to advise you here on transmission lengths and suitable cables.

When transmitting the Profinet signal over a long distance with a copper cable, there may be problems with the transmission of the data.

Alternatives to Profinet with copper

How can it be implemented?

Together we worked out an alternative.

In this case, the alternative to transmitting the Profinet signal on the long travel is a chainflex fibre optic cable.

With a fibre optic cable you can also transmit a signal over long distances. This is due to the significantly lower attenuation values compared to a copper cable.

The customer now uses a fibre optic cable in the system to transmit the Profinet signal. With the help of a transducer, the electrical signal is turned into an optical signal in front of the fibre optic cable and vice versa.   Since then, there are no problems transferring the data and the system consisting of e-chain and cables operates smoothly with a service life guarantee of up to 36 months in the application described.

Are you from the crane industry or material handling and have applications with long travels? Please contact us! We will plan the right cables for your project with you.

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