Press Releases

Moeller Electric Automates Opencast Excavator

Moeller Electric has completed automation of the first Demag-11 hydraulic excavator at New Vaal Colliery, Vereeniging.

This is the first automation project to be undertaken by Moeller Electric in an opencast environment, and the first of its kind to reduce customer cost by equipping personnel with the skills needed to build and programme the PLC panels in-house.

New Vaal supplies coal at the rate of 17-million tons per year to Eskom's 3600MW Lethabo power station, and is South Africa's first major colliery to mine coal by opencast methods from reserves previously mined
underground.

Automation by Moeller Electric comprised the design, installation and commissioning of a Moeller PS4-201-MM1 PLC with MV4 touch screens for the Demag-11 model 285 hydraulic excavator, followed by comprehensive training of New Vaal personnel on the complete system.

The first excavator has been commissioned and is now operational.

New Vaal awarded the automation contract to Moeller Electric against stiff international competition, following the faultless operation for more than two years of a fire panel protection system designed and installed earlier by Moeller Electric on several of the colliery's Demag-11 machines.

A spokesman for the colliery said that Moeller Electric's performance on the automation contract had been excellent.

Automation by Moeller PLC now brings the major additional benefit of self diagnostics to the giant machine, reducing downtime and maintenance costs, and increasing productivity.

Whereas before a machine breakdown would take up to two hours for a mechanic and/or an electrician to diagnose, self-diagnostics now indicate immediately whether the fault is mechanical or electrical, and in which part of the machine the fault lies.

The automated system will also shut down the excavator if a potentially damaging fault occurs, such as a rupture in a hydraulic pipe. Before automation, it was possible for the operator to continue working the machine to the point at which expensive mechanical damage occurred.

Training of New Vaal personnel took place in phases over more than a one year period, allowing the colliery to build and programme the PLC panels in house under the guidance of engineers from Moeller Electric.

Commenting on the successful commissioning of the first machine, Gert Jonker, manager for technology and training at Moeller Electric, said that the goal of in-colliery expertise in both panel-building and programming had been achieved.

"This is a vital capability," said Jonker, "because these machines must work around the clock if maximum productivity is to be achieved. The colliery cannot wait for help. Personnel there must be able to carry out the repair themselves."

Moeller hardware for the Demag-11 excavator PLC comprised a central processing unit with analogue and digital input-output modules, temperature input and monitoring modules, a touch screen and memory expansion module.

Software included a topology configuration, and function blocks for the boom, compressor control, filter, trip and pressure indication, lubrication, temperatures, slew control, travel control and other systems.

Security is provided by four levels of password, with provision for the addition and removal of users at will. Automatic log-out is performed by the PLC programme.

Alarm reset and manual override is possible from the screen.

The automation project at New Vaal is expected to assist Moeller Electric in obtaining further, similar projects within the Amcoal Group, of which New Vaal Collieries is a subsidiary.

« Back