Belden Supplies Hirschmann Brand Optical Communications Technology for Herrenknecht Tunnel Boring Machines

Two identical tunnel boring machines (TBMs) were used to cut twin 9385-meter holes through solid rock. Each of these machines is 230 meters long and weighs 2,500 tons. Because the machines have special data communication requirements, an optical Profibus network incorporating Hirschmann OZD Profi 12M fiber interfaces were installed.

Wayss & Freytag Ingenieurbau was responsible for planning and implementing this network. Project Manager Roberto Piacentini explains: “The physical properties of optical cables mean that there is no electromagnetic interference, which is extremely important in view of the long transmission paths along the power cables of the tunnel boring machines.”

Initially two kilometers long, the fiber optic cables were gradually extended to a length of ten kilometers in order to keep up with the progress of the TBMs. Both ends of the cable were equipped with fiber interfaces to transmit the Profibus signals. On the two TBMs and in the control room at the mouth of the tunnel, the same interfaces act as a link to the local PLCs.

“These fiber interfaces, which constantly monitor the signal quality, are characterized by a robust hardware design, so they always permit secure data communication despite strong vibrations, impacts and high temperatures,” says Piacentini.

Redundant, fail-safe networks can also be implemented using the fiber interfaces. However, for the Katzenberg tunnel this was deliberately avoided. “Because the TBMs can operate self-sufficiently for a time using the information stored in the local control computers, a brief interruption of data connectivity to the tunnel mouth could be tolerated,” explains Alfred Huber, project manager at Belden. “This greatly simplified the cabling and made it much easier to handle.”

The approach adopted by Wayss & Freytag Ingenieurbau for secure Profibus data transfer via fiberoptic cables has proven itself in the construction of the Katzenberg tunnel in the same way as have Belden’s active components. Nevertheless, there are already signs of other data protocols being used.

Product Manager Rolf-Dieter Sommer, who is responsible for Hirschmann fiber interfaces at Belden, explains: “Telephone connections between the TBMs and the control center at the tunnel mouth are already implemented using Voice over IP. We are currently working on simultaneously and reliably transferring control signals over an Ethernet cable.”

Hirschmann, a Belden Brand, manufactures Ethernet switches, wireless access points, firewall/VPN routers and network management software for harsh industrial environments. The Hirschmann brand stands for experience and expertise in the automation, power transmission and distribution, transportation and energy industries, having pioneered the development of Ethernet as a common standard for industrial control systems. Hirschmann products ensure hassle-free and secure data communication under the harshest conditions due to their ruggedized design and construction.