Video recorder survives boring conditions

Margate, UK – An ABB videographic data recorder was withstood use in an application 30 metres underground. Installed on a tunnel boring machine (TBM) mining a 1400 metre tunnel through chalk under Margate, the SM3000 provided fault-free recording despite continuous exposure to high temperatures, humidity, vibration and chalk dust.

The TBM was used to construct a tunnel to carry foul and treated water pipes, as part of a project undertaken by Costain Ltd on behalf of Southern Water. The tunnel was built to carry the pipes under residential areas and roads, where open cut work would be unfeasible.

The ABB SM3000 recorder was initially ordered by Costain’s chartered electrical engineer, Martin Godfree, to record data from pressure and other transducers in the TBM’s hydraulic propulsion and articulation rams.

“Driving the TBM with the information that the [data recorder] provided on the screen enhanced the driver’s ability to avoid undue stressing of the main bearing. A failed bearing costs many thousands of pounds to replace and could have taken twelve or more weeks to fit,” said Godfree.

“To carry out these repairs would have meant bringing the TBM to the surface either by dismantling it and withdrawing the parts through the constructed tunnel or by sinking a shaft in front of the TBM and lifting it out. Either option was no small task. We therefore decided to install the SM3000 to provide the driver with enhanced information and to record the TBM’s behaviour.”

By collecting and analysing the data, it was possible to identify abnormalities in the various parameters recorded and carry out the necessary steps to improve them.

With 36 recording channels, the ABB device also allowed data to be collected from the TBM’s laser distance finder, its r.p.m. indicator and steering transducers. All the information was relayed to the site workshop on the surface via a UTP cable from the SM3000’s built-in Ethernet connection.

The videographic recorder transmitted real-time data on the TBM’s progress and course via the cable which was dispensed from a drum at the TBM axial speed of up to 4mm per second whilst mining.

“We previously assessed progress by counting the concrete rings installed and noting the time taken,” said Godfree. “With the [data recorder’s] Ethernet connection, we were able to have an at-a-glance overview of the machine’s progress as it happened.”