Dynamic restructuring in the Polish mining sector and requirements of the global mining industry have contribute to new challenges for mining machinery manufacturers, including producing more efficient and reliable longwall systems.
The KSW-2000E longwall shearer is a recent development of ZZM, part of the Kopex Group. Global shearer manufacturers are required by end-users to enhance total installed power on the shearers above 2MW.
The KSW-2000E longwall shearer is equipped with two 950kW cutting drum motors and one 110kW crusher motor with a supply voltage of 3 x 3.3kVAC, a hydraulic pump motor with a supply power of 45kW, two 120kW haulage motors with a supply voltage of 3 x 1.0kVAC. The total power of the motors installed on the shearer may be as high as 2,195kW. ZZM developed new ranging arms, haulers and electric apparatus box for the KSW-2000E.
Every motor supplying a rated voltage of 3 x 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 way 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)
The haulage system and pumps for hydraulics are fed from a transformer with the ratio 3 x 3.3kV / 3 x 1kV, also equipped with safety systems. Two 120kW / 1kV motors that are mounted on the haulage system are individually fed from two converters, which have a supply voltage of 3 x 1kV, and enable electromagnetic braking of the motors. This results in an energy return into the feeding system.
The main advantage of this solution is the elimination of power resistors that discharge energy in the indirect converter circuit during electromagnetic braking of the motor. Power resistors promote heat loss inside the electric apparatus box and also affect the heat balance of the longwall system. Applying two independent converters leads to power optimisation of the haulage system.
Research and operating experience gathered have shown that mating the shearer track wheel to the AFC ladder influences the duty dynamics of the haulage system. When the bolt pitch is unbalanced, momentary gains in load in specific drive units are enhanced, which leads to interaction between them. In order to reduce this, a new control system of haulage drives has been developed.
Responsibility for the elimination of temporary mechanical disturbance has been moved from the shearer central computer to converters. This has enabled elimination of any delays in transporting and calculating that occurred in the past.
Advanced regulation techniques implemented in converters with a superordinate regulatory system make the haulage system very dynamic, flexible and maximise the installed power. 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. This haulage system, together with haulage regulators depending on the cutting drum loading and temperature correction algorithm, enables the executing of optional mining modes.
The 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.
The dispersed control system based on CAN trunk line is used to control the machine. With this solution the connection number inside the electrical apparatus box was reduced and 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. The external spark-proof CAN trunk line is connected to all the installed spark detectors responsible for measuring temperature, pressure, flow, velocity, level and localisation.
The central monitor is the most important element of the whole system. This 15in high-resolution monitor visualises all the parameters being monitored and any machine damage.
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.
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. The reference web is determined by the shearer being programmed during its first route as the machine remembers the basic parameters that are fundamental for the coal cutting process, for example, monitoring changes in positioning cutting drums, crusher, guards of a longwall shearer and its velocity, depending on the distance proceeded in the longwall. Pressing the auto button means automatic imitation of the system and subsequent cuts are made automatically, but online corrections may be implemented optionally.
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