Shield control systems

Communication of the different control units on the face has been established via two independent bus systems. The shield control units are connected via the so-called adjacent bus. This serial bus is designed for transmitting status messages and measuring values from the ASG’s to the master control unit.
Control commands and synchronization telegrams of the master control unit are sent via the so-called face bus. This bus is of the parallel type. Therefore, the support can be safely controlled even if a number of ASG’s fail resulting in a malfunction of the adjacent bus.

The connection to the control room at the surface is generally made via optical fibre. The connection to the face communication system underground can be established in two different ways.
When using a master control unit of the older type (iZA) an explosion-proof PC is utilized additionally. The master control unit transmits its data to this PC that presents them in a clearly arranged visualization. From this PC the connection is provided to the fibre optics connection to the control room.
When using a master control unit of the latest type (iLCC) an explosion-proof PC is not necessary. The iLCC has its own graphics modules on which the visualization can be displayed. This master control unit can additionally communicate direct with the control room via optical fibre ethernet. A (slower) cable-based data transmission to the surface can be offered as option.

The longwall control center is the interface between the shield control units and the control room at the surface. It processes the sensor values of the ASGs, transmits control commands and controls any automatic functions that can be operated. It is generally possible to use up to two longwall control centers per face, one at each drive end.
In a face layout with one longwall control center the unit is positioned at the intersection of face and entry. If a shield control unit fails the data connection up to the defective shield control unit will be maintained via the iLCC.
The shield control units whose communication to the iLCC is interrupted cannot be controlled in automatic mode. Individual functions can still be operated manually.
In a face layout with two longwall control center units the latter are positioned at the intersection between face and entry. One unit is located at the headgate drive, the second unit at the tailgate drive. In normal operating mode, both iLCCs are connected to the face bus and the adjacent bus. The unit at the headgate drive takes on the function of the master, while the unit at the tailgate drive is on standby, i.e. only one unit at a time is active.
If a shield control unit fails the data connection up to the defective shield control unit will be maintained via the headgate longwall control center. The remaining shield control units are then controlled via the tailgate iLCC.

In order to ensure an economical and at the same time fail-safe power supply for the shield control units the latter are combined to form so-called power groups. Depending of the required functions several ASG’s are operated at one power supply unit. The first ASG is connected with the power supply unit direct. The other ASG’s are supplied via the SKK28 connection. Their port for the power supply unit is provided with a strap plug.

In modern underground mining generally two basic methods of excavation can be applied.
Seams of considerable thickness are mined by means of shearers. The swivelling ranging arms permit a flexible control of the area to be extracted.
In low seams, however, plow systems are mainly the first choice. Due to their construction, these systems have different control requirements. The rigid design of the plow does not allow it to change direction automatically, for example. Digging or climbing of the mining machine is thus effected via the inclination angle of the conveyor. For a continuous and exact control of this mechanism Tiefenbach Control Systems developed the „radio remote inclination control for conveyors“. We also offer suitable products for a wide variety of further components required for a plow face.

Optimum face visualization is indispensable for a reliable and accurate control of the mining operation. For this purpose, Tiefenbach Control Systems has the VisuLx_Client on offer.  The operator in the central control room has all relevant information available at a glance. Thanks to the intuitive operation the risk of user errors is minimized and a fast reaction to unexpected events ensured. The visualization computer allows to read out both the complete face and each individual shield control unit.
All events and faults are logged and can be evaluated by means of the respective tools.