RiTE Gacko, Electrical Equipment revitalization of the Continuous Systems in "Gracanica" Open Pit Mine, Gacko, Republika Srpska

The project includes the reconstraction and replacement of electrical equipment on 20 machines which are parts of two ECS systems (Excavator - Conveyer -Spreader) within RiTE Gacko (mine and power plant Gacko). Existing machines have operated for about 30 years and  in order to ensure further smooth operation and maintenance of the capacity of the entire system, it was necessary to carry out a complete reconstructuring of mechanical and electrical equipment.

The total installed capacity for ECS 1 and ECS 2 is about 12MW. The scope of the contracted work  included:


  • Construction electric design and as - built design;
  • Delivery of electrical cabinets with built-in low voltage equipment;
  • Delivery of new electric motors and frequency inverters;
  • Delivery of control cabinets;
  • Application software;
  • Commissioning;
  • Training.
The First ECS System has the following machines:
  • Bucket Wheel Excavator ER 1250;
  • Loading unit - transporter P 1600;
  • Six rubber belt conveyers with;
  • Spreader ARs 1200.

The second ECS System consists of:

  • Bucket Wheel Excavator ER 1250;
  • Loading unit - transporter BRs 1200;
  • Six rubber belt conveyers with;
  • Spreader P 1600.

It has been planned that the third Excavator  ER 1250 work combined for both ECS systems, and that the spreader OS 1600 work within combined systemin the  field C, PK „Gračanica”, Gacko.The first ECS system has been put into operation. The remaining machines will be put into operation, by the end of August 2013.

Distribution systems (low and medium voltage plant), the resistor starters, transformers and control systems are housed in a container-like room with heat and insulation coating and air conditioning, selected according to the dissipation. The control system is based on a programmable logic controller - PLC with distributed I / O units (input / output units). Supervising, monitoring, and adjusting of relevant parameters of the control system of the machine is done via the operator panel. Between neighboring machines it is designed the exchange of blockade conditions terms by a wired connection, by potential-free contacts. It was also set the radio data transmission system. It can output the emergency stop  and machine stop signals.

Bucket Wheel Excavator ER 1250

Machine ER 1250 is a Bucket Wheel Excavator on crawler tracks with rotating arms. It is designed for digging overburden in depth and height block work. The capacity is 1250 m3 of solid mass/h. Installed capacity is 1100kW. Old, existing motors on the drives of the bucket wheel, feeder, conveyers, superstructure lifting and rotary motion and cable drum are replaced by new three-phase squirrel cage asynchronous motors.Control and management of these motors is achieved via single drive frequency converters and multi-drive frequency converters with recuperation.Control is carried out by the operator from the booth on the superstructure. A distributed I/O unit is located at substructure. Connection with the superstructure is achieved via PROFIBUS amplifier and slip rings.

Loading unit - transporter P 1600


Loading unit - transporter is designed for materials handling from bucket wheel excavator to the transportation system.  It is, as excavator, crawler tracks type machine with the reception and disposal arms  that can rotate. Installed capacity is 750kW.
Old drives on superstructure rotary motion, receiving conveyer and cable drum are replaced by  new three-phase squirrel cage asynchronous motors. Control and management of these motors is achieved via a single drive frequency converters. Disposal conveyor motor is asynchronous slip-ring motor 6kV, 250kW, with rotor starters resistors. Operator from the booth on superstructure controls the machine. Disposal arm control and positioning is performed from the another cabin on the superstructure. Part of the control system, which is located on the substructure, is connected through wireless link with the superstructure. Connection devices switch wireless PROFINET networks to PROFIBUS network. (IWLAN / PB Link PN IO).


Conveyers with rubber belt

Within first ECS, there are 6 of rubber belt conveyors that are designed for continuous transport of material from the excavator or loading unit - transporter to spreader. Each conveyer consists of:

  • Two motors power 250kW, 6 kV (asynchronous slip-ring motors);
  • Belt tensioning motor;
  • Spillage belt motor;
  • Thrusters.

Each transporter has its own MV anf LV switchgear station, and operator cabin to control the machine.

Spreader ARs 1200

Machine Ars 1200 is a spreader on on crawler tracks with rotating arms. It transfers material from the conveyor system to the dump. Power supply of all consumers is on 0.5 kV voltage level. The installed power is 500 kW. Machine is operated from the operator cabine located on the superstructure.


Vase Pelagica 30
11000 Belgrade, Serbia
+381 (0)11 3699 080
+381 (0)11 3699 939
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