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KSW- 2000E- a new generation of longwall shearers

Tuesday, September 15th, 2009

Dynamic restructuring process in the Polish mining sector and requirements of the global mining industry contribute to new challenges the mining machinery and equipment manufacturers have to face.
Optimization of the mining process that results in enhancing coal output enforces a high efficiency and reliability of the equipment that compose a longwall system. The longwall system is based on the shearer and its efficiency as well as output influence crucial technical parameters of the mining process. Reliability is a factor the designers are focused most in modern shearer constructions.
The KSW-2000E longwall shearer is a newly developed construction of ZZM S.A. and has been designed to meet the above said parameters. Experience in shearer manufacture made it possible to gather real exploitation data and detailed statistical analyses aimed at determining weak and strong sides of the prior constructions based on those data. Analyses results were fundamental for constructional assumptions of the KSW-2000E.
Global shearer manufacturers are required by the end-users to enhance total installed power on the shearers above 2MW. The KSW-2000E longwall shearer is equipped with two 950 kW cutting drum motors and one 110 kW crusher motor with a supply voltage of 3×3.3kV; AC, a hydraulic pump motor with a supply power of 45kW, two 120kW haulage motors with a supply voltage of 3×1.0kV; AC. Total power of the motors installed on the shearer may be as high as 2,195kW and it means that a development of completely new constructions of ranging arms, haulers and electric apparatus box are requested.
Every motor feeding way of a rated voltage 3×3.3kV is equipped with a complete safety set including:
• motor overload protection system,
• relays for monitoring and detecting low earth insulation condition of every feeding ways in a non-voltage state,
• relays for checking continuity and resistance of the external coat of the insulated cable feeding a motor (requirement of Polish mining law).
Haulage system and pumps for hydraulics are fed from a transformer of the ratio 3×3.3kV/3x1kV, also equipped with proper safety systems.
Two motors 120kW/1kV mounted on the haulage system are individually fed from two converters whose supply voltage is 3x1kV and enables electromagnetic braking of the motors fed. It results in energy return into feeding system.
The main advantage of this solution is elimination of power resistors that discharge energy in the indirect converter circuit during electromagnetic braking of the motor fed. Power resistors promote heat losses inside electric apparatus box and also affect heat balance of the longwall system. Applying two independent converters leads to power optimization of the haulage system. Research and operating experience gathered have shown that mating the shearer track wheel to the AFC ladder is the crucial factor influencing duty dynamics of the haulage system. Unbalance of the bolt pitch enhances momentary gains in load in specific drive units and leads to interaction between them. In order to reduce the above mentioned phenomena a new control system of haulage drives that enables an effective reduction of those disturbances on the whole system has been developed.
Responsibility for elimination of temporary mechanical disturbance was moved from the shearer central computer to converters. It enabled elimination of any delays in transporting and calculating that occurred in the past. A high dynamics of the haulage system requires sampling time for adjustment of the haulage system that differs from sampling time necessary for adjustment of the other tasks included in controlling the mining process of the shearer and it was the reason of separating them from each other. Advanced controlling algorithms applied made it possible to detect any mechanical disturbances of the haulage unit by each converter separately and to react in time.
Advanced regulation techniques implemented in converters with a superordinate regulatory system make the haulage system very dynamic, flexible and maximize the installed power. This haulage system together with haulage regulators depending on the cutting drum loading and temperature correction algorithm enable executing optional mining modes.
Control system is equipped with so called “mining programmes” that may be switched over, depending on geological conditions of the longwall or on technical requirements of coal assortment to be mined.
Dispersed control system based on CAN trunk line is used to control the machine. Thanks to this solution connection number inside the electrical apparatus box was reduced and it is expected to improve reliability of the shearer considerably. The central unit of the system is resistant to environmental conditions such as temperature and humidity in a higher degree. The whole system was divided into so called functional blocks including I/O local interfaces responsible for data acquisition in the installation place.
Similar solutions based on CAN trunk lines were used in the external measurement and execution units. External spark proof CAN trunk line is connected to all the installed spark detectors responsible for measuring temperature, pressure, flow, velocity, level and localization.
Central monitor is the most important element of the whole system. This 15-inch high resolution monitor visualizes all the parameters being monitored and any machine damage states. In case of damage it displays all the parameters necessary for detecting the damaged circuit, indicating a specific part of the machine documentation and approaching the circuit to damage. Communication between control system and the monitor is executed by Ethernet, the internal network that supplies data to the monitor and to external visualization system.
The KSW-2000E shearer is equipped with appliances enabling data transmission through Ethernet, using TCP/IP irrespective of the medium applied in the longwall system such as a feed cable, optical fibre or WiFi.
The shearer operator may select a controlling source, either a remote (radio) or a local one. Radio system enables not only remote control but also remote finding the requested data being monitored and remote viewing reports in case of a damage. Thanks to this solution the shearer operator need not approach the monitor. It is particularly important if the shearer length exceeds 14m.
The KSW-2000E may be optionally equipped with an automatic mining system, so called reference web and installation of precise ranging arm position sensors, a crusher and modification of the shearer body were required to achieve this aim. Basing on those measurements, current shearer location along the longwall is determined and this parameter combined with very precise monitoring the shearer route enable cut mapping. The reference web is determined as follows: the shearer is programmed during its first route and the machine remembers basic parameters fundamental for coal cutting process, e.g. monitoring changes in positioning cutting drums, crusher, guards of a longwall shearer and its velocity, depending on the distance proceeded in the longwall.
Pressing AUTO button activates automatic imitation system and subsequent cuts are made automatically but on- line corrections may be implemented optionally.
Combining this solution with analysis of the waste rock possible location enable implementing a shearer into a superordinate control system of a longwall complex operation. Superordinate systems integrate local control systems of roof support, longwall shearer, AFC and belt conveyor haulage drives using Ethernet transmission system with TCP/IP protocols.
The KSW- 2000E longwall shearer was presented for the first time officially during the World Mining Exhibition MINING EXPO 2008 in Sosnowiec, Poland. The machine aroused a big interest and was awarded the 1st prize in New Technologies category. Since end April 2009 the KSW-2000E has been operated successfully at the KWK Ziemowit (the Ziemowit Coal Mine), Poland, in the longwall No. 905.
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